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Technical Sessions

Educational Technical Sessions

RETC is proud to present technical sessions hosted by some of the leading innovators from the tunneling industry.

Sunday, June 16, 2019 I 1:00 pm – 4:30 pm

Specialty Session: Panel Discussion: Complex Underground Infrastructure Programs – Challenges, Observations and Guidelines

Chairs: Gregg Davidson, McMillen Jacobs Associates
Colin Lawrence, Mott MacDonald

Facilitator: Robert Goodfellow

Facilitated workshop/forum (debate) where:

  • prospective first-time tunnel owners can ask, listen and learn more about procurement, selection, execution and delivery of underground projects, and
  • experienced practitioners can ask questions and share information

The workshop goal is to open up dialogue flow between all parties for the benefit
of the industry.

Monday, June 17, 2019 | 8:30 am

SEM/NATM 1 – Regency A

Chairs: S. Price, Walsh Group, Rutherford, NJ
K. Dombroski, McMillen Jacobs Associates, Mayfield Heights, OH

8:30 am

8:35 AM
Bank Station Capacity Upgrade an Innovative Contractor Engagement Model
E. Fernandez, DRAGADOS, Madrid, Spain; J. Ares, DRAGADOS UK, London, UK and A. Sanz, DRAGADOS, Madrid, Spain

Bank is one of the oldest stations within the London Underground scheme, developed from 1884 onwards and reaching its present form in 1991. As some areas are close to saturation and the demand trend continue, it was decided to upgrade the station, through an Innovative Contractor Engagement (ICE) procurement model, focusing on adding value and long-term social benefit. Sprayed Concrete Lining and traditional timber headings have been selected for this Design & Build contract. This paper describes the ICE, the challenges encountered at design stage and the solutions applied during the construction to minimize the impact on the operational railway.

8:55 am
R. Arnold, Innsbruck, Austria

The Herrschaftsbucktunnel is located near Rheinfelden, Germany in close vicinity to the Swiss border. This highway tunneling project with two parallel tunnels and a length of approximately
480 meters is excavated applying the New Austrian Tunneling Method (NATM). Due to the difficult geological conditions and a cross section of 160 m² in the Southern tunnel, it was required to make use of a complex exploratory drilling program. The paper describes the challenges of NATM tunneling in difficult geology in combination with low overburden and large cross sections.

9:15 am
Steep Inclined SEM Excavation – Successful Execution Applying Drill and Blast
R. Griesebner, BeMo Tunnelling, Innsbruck, Austria

Construction of the border crossing hydro power station GKI in Tyrol`s upper Inn-valley required excavation of an inclined penstock tunnel. Equipment used during excavation of the 385m long 30% inclination with a diameter of 4,7m needed to provide sufficient traction to manage climbing the rock surface. Work Safety was of highest concern and required special measures which will be highlighted in the paper. Varying geological conditions required a flexible and experienced team of SEM specialists on site. The full range of SEM excavation from full face excavation to excavation in several partial steps were needed in the inclined tunnel drive. The paper describes the challenges faced in connection with these unusual conditions.

9:30 am
Coffee Break

Soft Ground Tunnelling Techniques for the Mining Industry
J. Anderson, Golder, Saskatoon, Saskatchewan, Canada;

The use of wet-mix structural sprayed concrete support has become increasing prevalent in the tunneling industry over the last 50 years, being used to support both soft ground and hard rock conditions in temporary and permanent cases, whilst the mining industry has typically concentrated on using shotcrete, bolts and mesh as ground support. These fields do not typically cross over, however, when establishing a new development in South America, initial development through approximately 70m of saprolite and weak rock was required prior to driving 2 km of traditional hard rock drifts. Saprolite is a heavily weathered rock material that behaves similarly to clay, and is common in humid and tropical climates. It inherits some of the relic structure of the decomposed rock, along which ground water flow can be highly variable. The material stability typically improves with depth prior to intersection with the un-weathered rock mass. The Sequential Excavation Method was identified during the feasibility stages of the Project as the most efficient and safe method of construction for the initial 70m, prior to transition into hard rock development. This paper presents the design and construction considerations of the Project, including discussions of the challenges met in implementing such a scheme in a remote location, with difficult ground conditions and with a hard rock mining team.

10:05 am
Implementation of Automation and Digitization in Tunnel Waterproofing and Grouting Practices
S. Lemke, Renesco Inc, Herndon, VA; A. Heizmann, Renesco GmbH, St. Leon-Rot, Germany and T. Kearney, Renesco Inc, Herndon, VA

Groundwater intrusion into tunnels is one of the most formidable challenges that face the service life of all underground structures. This dilemma becomes more profound when one considers a tunnel’s service life requirements of more than 100 years. While several legacy factors contribute to the overall success of these structures like design, quality, materials, engineering, construction, and environmental considerations. The tunnel industry in North America has been slow to adapt to new key materials, automation, digitization and a multidisciplinary approach in the performance of this type of tunnel work. In Europe, automation and digitization are entering the tunnelling industry for Tunnel Waterproofing and Grouting. Systems such as automatic sheet-waterproofing application via hot-melt technology, spray-on waterproof coatings robotically applied and automated monitoring and associated digital reporting systems control the grouting placement procedures thus insuring that grout quantity and quality meet project specific standards. Real time monitoring incorporates the data acquisition material workflow, processing of information and the immediate visualization of gathered information to enable in timely decision making and enabling the contractor to make immediate project specific adjustments to the construction process. Automation and digitization case studies for waterproofing and grouting applications for projects in Switzerland and Germany will be provided.


Pressure Face TBM Case Histories – Regency B

Chairs: D. VonPlaten, Traylor Bros. Inc., Alexandria, VA
F. Huber, Metro Vancouver, Burnaby, BC, Canada

8:30 am

8:35 am
Conditioning the Clog: Advancing EPB Technology Through Mixed Transitional Ground
E. Comis, McMillen Jacobs, Mayfield Heights, OH; M. Moccichino, McMillen Jacobs, Vancouver, BC, Canada and P. Raleigh, McMillen Jacobs, Pasadena, CA

Earth Pressure Balance (EPB) Tunnel Boring Machines (TBMs) have a difficult time excavating through “mixed transitional ground“ [Oliveira and Diederichs (2016)]. Soil conditioning plays a critical role in achieving the desired qualities of the excavated muck inside the excavation chamber and the delicate balance between clogging and maintaining face support. Soil conditioning laboratory tests are often completed during the planning phase prior to TBM excavation in an effort to have a starting template, reduce risks, costs and improve EPB performance right out of the shaft. Often these conditioning tests show considerable promise in the lab but don’t deliver even where the excavated materials are relatively homogeneous and with even less success in so-called “mixed transitional ground“. Very slow advance rates, high torque and thrust and inevitable clogging of the cutterhead openings has been experienced on a number of recent projects as a result of varying amounts of clay in the face. This paper will compare earlier remarks from literature with the observations made during the excavation of the Ohio Canal Interceptor Tunnel in Akron, Ohio, USA (OCIT) and other recent projects, particularly with regards to very slow advanced rates, rapid tool wear and clogging of the cutterhead. It also discusses the limits of desktop versus empirical clogging evaluations with respect to actual clogging experienced during tunnelling and mitigation measures that have been introduced during the excavation which helped decrease wear and increase advance rates.

8:55 am
Tunneling in Mixed Face Conditions: An Enduring Challenge for EPB TBM Excavation
J. Clark, The Robbins Company, New Delhi, India and P. Verrall, Afcons Infrastructure Ltd., West Mumbai, India

EPB TBM tunneling in mixed face conditions—partially in both rock and soil--is inherently problematic for even the most experienced crews. Over-excavation, excessive damage to cutter tools and regular cutterhead interventions are major challenges when negotiating mixed face geology. This paper will draw from real field experiences, including successful bores in abrasive rock and soil at India’s Chennai and Bangalore metro projects, to determine the optimal operational parameters for TBMs in such conditions. It will also address reduction of air losses to facilitate cutterhead interventions under hyperbaric conditions when installation of safe-haven grout blocks is not an option due to surface structures.

9:15 am
Effectiveness of Risk Mitigation Strategies for Large Diameter One-Pass Tunnels in Mixed Ground from Ohio Canal Interceptor Tunnel Construction
C. Caruso, McMillen Jacobs Associates, Mayfield Heights, OH; D. Rendini, Parsons, Akron, OH; G. Visca, DLZ Ohio, Inc., Akron, OH; D. Dobbels, McMillen Jacobs Associates, Burlington, MA and M. Wytrzyszczewski, City of Akron Bureau of Engineering, Akron, OH

The City of Akron, OH is implementing a $1.4 Billion CSO Long Term Control Plan, which includes the construction of a TBM-excavated 27-ft ID 6,211 LF tunnel through rock and soil, the Ohio Canal Interceptor Tunnel (OCIT). In this paper, major risk mitigation measures considered for tunnel excavation will be reviewed from preliminary design through completion of tunneling, including specification of reaches for open and closed mode tunneling, probing, the use of hyperbaric interventions and safe havens for soft-ground cutterhead maintenance, and other measures. The effectiveness of these measures will be assessed retrospectively and other lessons learned will be presented.

9:30 am
Coffee Break

9:45 am
Preparation for Tunneling, Don River & Central Waterfront Coxwell Sanitary Bypass Tunnel Project in Toronto, ON
E. Alavi, Jay Dee Contractors, Inc., Livonia, MI, D. Cressman, Black and Veatch, Markham, ON, Canada and W. Hodder, Jay Dee Contractors, Inc., Livonia, MI

The Don River & Central Waterfront Coxwell Sanitary Bypass Tunnel Project in Toronto will extend approximately 10.5 km from Ashbridges Bay Treatment Plant west under Lake Shore Boulevard, north under Bayview Avenue and east through the Don River park area to the Coxwell Ravine Park. The tunnel will be mined by using a shielded tunnel boring machine capable of operating with a pressurized excavation chamber and lined by using a precast concrete segmental tunnel linear with an internal diameter of 6,300 mm and excavated diameter of 7,300 mm. In addition to the TBM excavated tunnel, the scope of this project includes two sections of tunnel using hand tunnel construction methods, five shafts corresponding to the locations of 5 sewer structures, eleven drop shafts, vent shafts, deaeration and adit tunnels to be design and constructed, two diversion structures and two consolidation sewers to be constructed using mainly open cut and shored excavation methods, 8507 Connection from the existing wet weather flow outfall to one of the shafts and North Toronto Sanitary Trunk Sewer from the existing sewer to one of the shafts. This paper summarizes the preparation work that has been done prior to the launch of the TBM.

10:05 am
Planning, Design and Construction of the Regional Connector TBM Tunnels
R. McLane, Traylor Bros., Inc., Long Beach, CA; G. Baker, Los Angeles County Metropolitan Transportation Authority, Los Angeles, CA; W. Hansmire, WSP USA, Los Angeles, CA; R. Drake, EPC Consultants, San Francisco, CA; D. Penrice, Mott MacDonald, Pleasanton, CA and D. von Platen, Traylor Bros., Inc., Long Beach, CA

The Regional Connector Transit Corridor project is a Los Angeles County Metropolitan Transportation Authority (Metro) design-build, light rail underground project that will connect two existing rail lines in Los Angeles (Contract No. C0980). The 3.1 km alignment with a total project value of $ 1.8 billion (US) includes construction within the Little Tokyo and Bunker Hill neighborhoods, and the Financial District in the heart of downtown Los Angeles. It will provide connections between the Metro Gold Line from Pasadena and East Los Angeles, the Metro Blue Line to Long Beach, and the Expo Line to Santa Monica. This paper describes the history of the tunnel planning, design and construction methods adopted that resulted in successfully completing the tunneling segment. Further, this paper outlines the pro-active partnership between the owner, Metro, and the Contractor, Regional Connector Constructors, a joint Venture of Skanska and Traylor Bros., to address project schedule and technical challenges including various differing site conditions and critical settlement control in low-cover EPB tunneling.

Environmental, Health and Safety – Regency C

Chairs: K. Wilson, LA Metro, Los Angeles, CA
L. Dalton, HNTB, New York, NY

8:30 am

8:35 am
Conception and Construction of a Tailor-made and Contractor-built Refuge Chamber for TBM and SEM Drives According to German Guidelines
R. Antretter, BeMo Tunnelling, Innsbruck, Austria

Very different and partially missing guidelines, different points of view by manufacturers and users, as well as a critical self-assessment including a risk analysis led to the decision to develop and build a refuge chamber by ourselves as a tunneling contractor. The goal was to use the refuge chamber on a 9m diameter TBM in Karlsruhe, Germany as well as in conventional SEM tunnels where long standalone periods were required. The chamber was tested and approved by simulation of design conditions under expert monitoring. Knowledge gained from this application was helpful for development of a national guideline and will contribute to further improvements of future rescue concepts.

8:55 am
Tunnel Ventilation System Measurements and 3D-CFD Modelling
M. Schöll and R. Gertl, ILF Consulting Engineers Austria GmbH, Innsbruck, Austria

The smoke extraction system of a 6 km long road tunnel consists of three ventilation stations for pointwise extraction in case of fire. Each ventilation station has three emergency fans, two of which operate simultaneously. To quantify the flow rate of each emergency fan combination, extensive flow measurements were performed. The required extraction flow rate was not achieved for several combinations of emergency fans. Therefore improvement measures, which reduce the pressure losses, were investigated using 3D CFD simulations and analytical approaches. After the suggested improvements were made, the flow measurements were repeated and the flow rates could be increased to the required level.

9:15 am
Minimizing Impacts to the Community and Commuters: Constructing the District’s Largest Tunnel along a Major Urban Artery
B. Levy, AECOM, Chelmsford, MA; M. Wone, District of Columbia Water and Sewer Authority, Washington, DC and J. Carl, Brown and Caldwell, Alexandria, VA

The District of Columbia Water and Sewer Authority is underway with the construction of the largest component of their project portfolio in one of the most heavily populated areas of the Nation’s Capital. The Northeast Boundary Tunnel is aligned along a major arterial roadway and targeted at relieving areas plagued by chronic flooding due to under-capacity sewers. This paper discusses the processes used to design community and traffic mitigation measures into the design-build contract and the actual implementation of these measures as part of the construction efforts. Focus will be placed on project milestones, mitigation of impacts, and safety.

9:30 am
Coffee Break

9:45 am
A Comparison of Breathing Gasses Used Under Hyperbaric Conditions
J. Costello, Ballard Marine Construction, Washougal, WA

A comparison of the various breathing media commonly used in commercial diving and in hyperbaric support of pressure-faced tunnel boring machines. The effects of various inert gasses, the role of hyperbaric oxygen, and saturation at both high and low pressures are explained. The decision-making behind selecting a proper breathing medium for a given pressure and work scope is explored. Equivalent air depths, equivalent narcotic depths, oxygen toxicity, adjustments for projects at altitude, and air saturation are discussed. A comparison of efficiency and productivity based on gas blends, associated costs, and decompression profiles is made.

10:05 am
Transit Tunnel TBM Vibration through Glacial Till
D. Jue, Wilson Ihrig, Emeryville, CA and T. Bergen, Wilson Ihrig, Bothell, WA

Tunnel excavation for the Central Puget Sound Regional Transit Authority (Sound Transit) University Link Extension (U-Link) was completed in 2012 and tunneling for the Northgate Link Extension was completed in 2016 in Seattle, Washington. In both cases, the tunnel was advanced under the University of Washington (UW), and there was concern that the vibration could be detected at nearby buildings and potentially interfere with sensitive research activities. This paper will compare the predicted and measured TBM vibration at the ground surface and in buildings above the tunnel alignment. The over-consolidated glacial till that underlies the region is a particularly efficient transmission medium for low frequency vibration. The predictions were based on available data collected in advance of the TBMs reaching the campus, ground vibration transmission tests and building coupling loss tests to evaluate the potential vibration transmitted into the buildings. Measurements were conducted outside and within the buildings. The University Link and construction used a (shield jack) TBM with a muck train to transport the excavated material and supplies to the TBM.

10:25 am
Commissioning of Tunnel Fire Life Safety Systems and Its Challenges
H. Heis and R. Gertl, ILF Consulting Engineers Austria GmbH, Rum, Austria

The rehabilitation of the electrical and mechanical systems of a 2.8 km twin-tube motorway tunnel in Austria was conducted in two phases by closing one tube for works and operating the other in bidirectional mode. It included some 20 systems, encompassing the upgrade of existing and addition of new systems, such as the high-pressure water mist system that was added to be used as an active fire protection system for the civil structure. The test procedure as part of final commissioning focused on the water mist and the ventilation system. The final proof of all systems, functions and interfaces was done during the live fire tests conducted for both scenarios, with and without activation of the water mist system.

Design and Planning – Acapulco

Chairs: D. Smith, WSP, New York, NY
N. Karlin, Skanska, Riverside, CA

8:30 am

8:35 am
Design and Construction Procurement for the Amtrak Hudson Tunnel Project
P. Rice, WSP USA, Inc., New York, NY; H. Cordes, WSP USA, Inc., Washington, DC; R. Flanagan, WSP USA, Inc., New York, NY and M. Nasim, Amtrak, Philadelphia, PA

Amtrak’s existing North River Tunnels below the Hudson River, built in 1910 by the Pennsylvania Railroad, were flooded and damaged during Superstorm Sandy and need to be rehabilitated. Because this work cannot be done without seriously impacting regional rail service, two new tunnels are proposed along a new alignment connecting the Northeast Corridor from Secaucus, New Jersey to existing Penn Station in Manhattan. Experience gained from the cancelled Access to the Region’s Core Project was used to expedite the Preliminary Engineering Design for the Hudson Tunnel Project. This paper provides descriptions of key project elements, expected construction methods and contracting approaches.

8:55 am
Crosstown Tunneling for Houston Surface Water Supply
S. Flores and T. Wanless, Black & Veatch, Houston, TX and M. McCure, Black and Veatch, Dallas, TX

As a means to comply with a mandated 90 percent reduction in groundwater extraction in Houston, the West Harris County Regional Water Authority is constructing the $700M Surface Water Supply Project. The 39-mile project traverses urban Houston and includes numerous tunneled sections for the 96-inch diameter steel pipeline. This paper is directed at the challenges involved in designing 19 soft ground tunnels that cross under major highways, city streets, streams and extensive utilities. The paper will focus on a locally unprecedented 4.3-mile long tunnel to be constructed through a narrow pipeline corridor in clays and sands under the groundwater table.

9:15 am
Times Square Shuttle Station Reconstruction
A. GRIGORYAN, WSP, New York, NY; D. PATEL, MTA NYCT, New York, NY; P. LUND, WSP, New York, NY and D. Campo, WSP, Lawrenceville, NJ

Times Square Shuttle Station is part of busiest subway complex in NYCT on curved alignment with three platforms serving three shorter trains. Paper discusses design of reconstruction methods for improving station operations by underpinning existing station, removing over 120 station columns, constructing new foundations, new structural support framing – columns and transfer beams. New foundations were developed to address varying rock quality. New underpass would be mined below operating tracks to provide additional station entrance and connect to 42nd street passageway. Trains would be supported by skeletonized tracks and micro-piles. All modifications would be performed from underground without 42nd street excavation.

9:30 am
Coffee Break

9:45 am
Liner Load Estimation for Pressure Balance TBM Tunnel Projects
T. Epel, M. Mooney and M. Gutierrez, Colorado School of Mines, Golden, CO

Pressure balance TBM tunneling has advanced to the point where it is routine to essentially match the face and annulus pressures around the TBM envelope. Resulting ground deformations are sensitive to the face pressure-ground stress ratio. The loading on segmental lining is impacted by this, and specifically the question of pre-convergence – the relaxation and arching of the ground prior to lining installation. With very little information about convergence-confinement in pressure-balance TBM situations. This paper addresses the loading on precast segmental lining during pressure balance TBM tunneling. TBM and lining load data from multiple projects is incorporated into the study.

10:05 am
Mixed Transitional Ground (MTG) Impact on a Dual Mode Rock/EPB TBM Utilization Factor. The OCIT Experience
E. Comis, McMillen Jacobs, Mayfield heights, OH; D. Chastka, Kenny Construction a Granite Company, Akron, OH and W. Gyorgak, McMillen Jacobs, Mayfield Heights, OH

For the first time in North America a dual mode Rock/EPB TBM, Ø9.26m bore in diameter, has been used to excavate the Ohio Canal Interceptor Tunnel (OCIT) in the downtown Akron area, USA. Tunneling was carried out at a uniform slope of 0.15 percent through ground conditions that consisted of soft ground, mixed face soft ground over bedrock, and bedrock. The Mixed Transitional Ground (MTG) resulted in the biggest challenge for the TBM. This paper will discuss specifically the influence of the MTG on the TBM Utilization Factor and will suggest possible countermeasures that can be adopted in these special geological conditions.


Monday, June 17, 2019 | 1:30 pm

SEM/NATM – II – Regency A

Chairs: C. Heinz, J.F. Shea, Indianapolis, IN
T. Peyton, WSP, Garrison, NY

1:30 pm

1:35 pm
Culvert Construction Under I-89 in Vermont Using the Sequential Excavation Method
J. Pearson, Stantec, Walnut Creek, CA, J. Prada, Stantec, South Burlington, VT and A. Dean, Stantec, Walnut Creek, CA

Following the deterioration of two large culverts under I-89 in Vermont, the Vermont Agency of Transportation (VTrans) issued a request for design-build proposals for replacing and enlarging the culverts. The winning team of JA McDonald/Bradshaw/Stantec selected the sequential excavation method of tunneling for the 21 foot wide x 13 foot high excavation which was used as temporary support for the culvert installation with permanent works consisting of both cast-in-place and precast structures. This paper will detail tunneling excavation support for the culvert replacement including an overview of the geological and geotechnical features of the project, a summary of modeling that was performed, and an overview of the methodologies used during construction.

1:55 pm
SEM Cavern Construction in Downtown LA
C. HERRANZ, Mott MacDonald, Los Angeles, CA; I. Hee, Skanska, Los Angeles, CA; D. Cerulli, Arcadis, Los Angeles, CA and C. Bragard; Traylor Bros., Los Angeles, CA

The Regional Connector Transit Corridor is a 3.1-km long light-rail (LRT) line that will link existing LRT and subway lines to improve mobility within Downtown Los Angeles and throughout the greater City area. A challenging and risky element of this $1-billion design-build project consists of a 287 ft long, 58 ft wide and 36 ft high track crossover structure which is being constructed at relatively shallow depth in soft rock beneath existing building foundations and major utilities using Sequential Excavation Methods. Through a combination of monitoring data, test results and field observations this paper correlates construction performance with design assumptions and analysis and demonstrates how collaboration between designer, contractor and owner is key to successfully adapt to changes during construction.

2:15 pm
SEM - Single Shell Lining Application for the Brenner Base Tunnel
T. Marcher, SKAVA consulting ZT GmbH, Innsbruck, Austria

The Brenner Base Tunnel is a railway tunnel between Austria and Italy through the Alps with a length of 64 km. The construction lot Tulfes-Pfons was awarded to the Strabag/Salini-Impregilo consortium in 2014. The construction lot includes 38 km of tunnel excavation work and consists of several structures such as the 9 km long Tulfes emergency tunnel. Such a service (non-public) tunnel does not necessarily require a tunnel lining system with two shells, but under certain boundary conditions can be achieved by a single shell lining approach. The required conditions and limitations for the single lining approach are reflected and a proposal for structural verification is provided. For verification approach a novel constitutive model for the shotcrete design is used.

2:35 pm
Shallow SEM Tunneling with Limited Clearance to Existing Structures: Predictions versus Observations

H. Yang and D. Penrice, Mott MacDonald, San Ramon, CA

Construction of the Downtown Bellevue Tunnel using the Sequential Excavation Method (SEM) has just been successfully completed. The soft ground tunnel, 2,000 feet long and 38 feet wide with very shallow cover, faced a number of unique challenges and design refinements that were managed and implemented during construction. This paper focuses on three such design refinements: tunneling within four feet of existing building basements, tunneling under an existing utility trench with 4 feet of vertical clearance, and eliminating pipe canopy and replacing 12-foot-thick overburden soil with controlled low strength material (CLSM) at the tunnel’s north portal. The predicted settlements and tunnel convergences compared well with the instrumentation monitoring results. Details of the analysis, design, and construction of these design refinements, together with the comparisons between the predicted and observed results, are presented.

2:45 pm
Coffee Break

3:00 pm
LA Metro Regional Connector Transit Project: Successful Halfway-Through Completion
M. Harrington and T. Vu, VN Tunnel and Underground, Inc., Los Angeles, CA

The Regional Connector Transit Project is a 1.9-mile long underground light rail system that will connect LA Metro’s Blue, Expo and Gold Lines in downtown Los Angeles. This $1.81-billion design-build project is expected to be completed in winter 2021-2022. The project consists of 21-foot diameter twin-bored tunnels, a 287-foot long crossover SEM cavern, three new underground stations (at 1st Street/Central Avenue, 2nd Street/ Broadway Avenue, and 2nd/Hope Streets), and cut-and-cover tunnels along South Flower, Alameda, and 1st Streets. Final designs have been completed and the construction has reached the halfway-through completion milestone. Bored tunneling was successfully completed with little to no ground settlements. Excavation of the 36-feet high by 58-feet wide, 287-feet long SEM cavern has started, with completion scheduled by early 2019. This paper will provide overview of design elements and challenges experienced to date, as well as an update of construction progress on major components of this complex transit project.

Pressure Face TBM Technology – Regency B

Chairs: M. Shinouda, Jay Dee Contractors Inc, Auburn, WA
B. Scofield, Traylor Bros., Inc., Stockton, CA

1:30 pm

1:35 pm
Forrestfield Airport Link: Project Challenges and TBM solutions
K. Bäppler and M. Strässer, Herrenknecht AG, Schwanau, Germany

A large number of successfully completed tunnelling projects in sensitive environment and airport areas show highest technical and quality standards of mechanized tunnelling technology mastering project challenges and individual tasks in the interest of customers, clients and the environment. The Forrestfield Airport Link, currently under construction in Perth Australia, is one of these projects in tackling challenges in sensitive airport area being sensitive to any kind of settlement and subsurface conditions. The paper highlights the project challenges that require a well-adapted TBM concept and the experiences with the use of variable density TBM technology from the manufacture’s point of view.

1:55 pm
Interpretation of EPB TBM Graphical Data
K. Rafie, Stantec, Richmond Hill, ON, Canada; S. Skelhorn, McNally, Hamilton, ON, Canada

Tunnel construction using a tunnel boring machine (TBM) involves a highly complex operation. Such processes generate large amounts of data that can be used for monitoring, reporting and analysis. Major TBM manufacturers have developed software systems to support tunnel contractors and their site teams in both data management and analysis. These programs are mostly web-based and have many advantages. Data acquisition cannot prevent breakdowns from occurring but can facilitate forensic investigations to quickly determine the root cause of a breakdown and provide basis for implementing corrective actions. This paper analyzes these data acquisition tools and presents case studies, primarily involving earth pressure balance (EPB) TBMs, to illustrate how the formation of critical interpretations can be made from user-defined charts and diagrams to diagnose issues and optimize TBM operational parameters.

2:15 pm
Tuen Mun Chek Lap Kok Project in Hong Kong. Innovative Technologies and Methodologies for an Outstanding Project

The Tuen Mun Chek Lap Kok Link (TM-CLKL) is a new road connection in Hong Kong. It will connect with a dual lane 5km long subsea twin-tunnel, the existing North Lantau Highway and the new Boundary Crossing Facilities situated close to the International Airport, to the new Tuen Mun Western Bypass and the existing Lung Mun Road in Tuen Mun. For tunnels construction, innovative solution have been put in place for overcoming the mixed face ground conditions (from 200 MPA granite to soft alluvium), the surrounding pressure reaching more than 5 bars at tunnel face. Two slurry TBMs have been used, one of them being 14m diameter, the second one being 17,63m diameter for the first 700m of the drive separating the TBM entry shaft to the ventilation shaft where this TBM has been converted into a 14m diameter TBM for excavating the 4,5km long subsea section of the drive. As ground condition are very demanding for cutting tools change, 2 solutions have been developed for changing in total about 2000 cutterdiscs on both TBM cutterheads. First saturation diving operation have been performed with professional divers being transferred with shuttles from the surface pressurized living habitat to the TBMs, and in addition 2 robotic systems capable to completely replacing cutterdiscs has been especially developed and installed on the TBMs. Finally, 42 out of the 50 cross passages between tunnels have been constructed using pipe jacking methodology adapted on purpose for the project.
The paper will present details of the innovative solutions performed there and some lesson learnt throughout the process.

2:35 pm
Curved Microtunneling Alignments in the Design Toolbox
D. Mast, AECOM, Cleveland, OH; A. Schreiber and F. Vincent, Northeast Ohio Regional Sewer District, Cleveland, OH; P. Dodds, AECOM Technologies, Inc., Columbus, OH; R. Dill, AECOM Technologies, Inc., Chelmsford, MA and P. Nicholas, AECOM Technologies, Inc., Seattle, WV

The Doan Valley Relief and Consolidation Sewer (DVRCS) is a Combined Sewer Overflow control project located in Cleveland, Ohio, with a recently awarded contract in the amount of $13.5M. The project is part of a Consent Decree agreement between the Northeast Ohio Regional Sewer District (Owner) and the USEPA, Ohio EPA and USDOJ. The project requires trenchless installation of over 3,137 linear feet (LF) of 72“ diameter sewer, approximately 1,475 LF of 48“ sewer via open-cut methods, flow control structures, and other appurtenant work items. During design, NEORSD and their design team, led by AECOM, identified over $4.5M in value engineering options. The project was also designed with significant flexibility in allowed construction means and methods. However, subsurface conditions on the State Route 6 tunnel alignment, combined with a desire to avoid mining shafts in the road right of way, led to the decision to specify curved microtunneling construction methods in the bid documents. This is the first project bid by NEORSD with a curved microtunneling construction requirement. This paper will highlight the successful optimization of the project, the ways the Owner and designer incorporated construction method flexibility into the bid documents, and the reasons for specifying curved microtunneling construction methods.

2:45 pm
Coffee Break

3:00 pm
Mechanized Tunneling at High Pressure – More than Just a Stronger Bulkhead
W. Burger, Herrenknecht AG, Schwanau, Germany

Mechanized tunneling at face pressures far above 50psi has become common practice in recent years. Closed mode TBM layout and operation at very high face pressure affects a large number of TBM design aspects from seal systems to chamber interventions. The paper will cover consequences, technical solutions and project examples of TBM design for high pressure applications.

3:20 pm
Proposal of Some Cuttability Indices for Evaluating the Performance of Excavation Machines
O. Su, Bulent Ecevit University, Zonguldak, Turkey; X. Wang, Chongqing Key Laboratory of Manufacturing Equipment Mechanism Design and Control, Chongqing Technology and Business University, Chongqing, China; Y. Liang and Q. Wang, State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, China

In this study, new cuttability indices are propounded based on peak cutting force, specific energy and the rock strength. These are the ratio of cutting force to uniaxial compressive strength (FC/σc), the ratio of normal force to uniaxial compressive strength (FN/σc), the ratio of cutting force to indirect tensile strength (FC/σt), and the ratio of normal force to indirect tensile strength (FN/σc), the ratio of specific energy to uniaxial compressive strength (SE/σc), and the ratio of specific energy to indirect tensile strength (SE/σt). For this purpose, a number of samples were collected from different regions in China and the mechanical properties of the collected samples were initially determined. Then, a series of cutting tests were carried out at the linear rock cutting machine by using a conical pick. The tests were conducted at the cutting depths ranging from 3 mm to 18 mm in unrelieved cutting mode. Moreover, the specific energy during the tests was calculated. As a result of the tests, the relationships between the cuttability indices reported above and depth of cut was investigated. In addition, another cuttability index, which is the ratio of cutting force to cutting depth (FC/d) was considered and the variation of cutting force to cutting depth ratio with the specific energy was examined. In conclusion, the statistical analyses indicated that the cuttability indices would be successfully used for designing the cutterheads and drums of excavation machines and evaluating the cutting efficiency of excavation machines.

Tunneling for Sustainability – Regency C

Chairs: K. Ward, Seattle Public Utilities, Seattle, WA
S. Sadek, Jacobs Engineering, Boston, MA

1:30 pm

1:35 pm
Hecla's Mobile Mechanical Vein Miner
C. Alexander, Hecla Limited - Lucky Friday Mine, Big Timber, MT; M. Eklind, Epiroc, Orebro, Sweden; M. Board and D. Berberick, Hecla Mining Company, Coeur d'Alene, ID and W. Johnson, Hecla Mining - Lucky Friday Unit, Mullan, UT

Hecla – Lucky Friday is an underground silver, lead and zinc mine that produces from depths over 2.3 kilometers (7,500 feet) below the surface. Technical issues at this depth include high rock temperature, seismicity and logistics. Lucky Friday has partnered with Epiroc to design, build, test and deploy a mechanical miner for primary ore production. Lucky Friday and Epiroc will provide an update and lessons learned from the final design, manufacture and testing of this machine.

1:55 pm
Lockbourne Intermodal Subtrunk Sewer – Historical Perspective and Lessons Learned
I. Halim, AECOM, Chelmsford, MA

The Lockbourne Intermodal Subtrunk (LIS) sewer project in the City of Columbus, Ohio, was originally designed as a 12-foot TBM tunnel that was later downsized into smaller 78-inch microtunnel to connect the existing BWARI tunnel to recently built intermodal facility and service future city developments. This paper describes the project history and factors impacting the design. Construction challenges and remedies will be presented which include major ground loss and occurrence of multiple sinkholes during the initial tunnel run. Lessons learned from these challenges will be further discussed. The project is currently scheduled for on-time completion in the spring of 2019.

2:15 pm
Great Hill Tunnel Inspection and Rehabilitation
D. Ebin and B. Lakin, McMillen Jacobs Associates, New York, NY; J. Schrank, McMillen Jacobs Associates, Nashville, TN and L. Marcik, South Central Connecticut Regional Water Authority, New Haven, CT

The Great Hill Tunnel, owned and operated by the South Central Connecticut Regional Water Authority, is a 100 MGD, 3,600-foot-long, 6-foot horseshoe-shaped raw water transmission tunnel that cannot be taken out of service and dewatered without installation of a bypass system.

During 2017, routine tunnel leakage increased dramatically, causing concerns that known defects were getting larger and that increased leakage signaled impending tunnel failure. This paper will discuss the rehabilitation program, which included manned inspection and repairs such as shotcrete, cement mortar patching, and contact grouting. It will also compare the manned inspection with earlier ROV inspections of the tunnel.

2:35 pm
LED Construction Lighting in Tunnel Projects
B. Astl, Lind Equipment, Markham, ON, Canada and J. Bresnen, Jennmar Civil, Pittsburgh, PA

LED lighting is commonly used in households, commercial settings, and as permanent lighting in completed tunnels. However, the use of LED lighting during the tunnel construction phase is less prominent. This paper outlines the benefits of using LED construction lighting in tunnels for contractors and other stakeholders. It also details the technical requirements for determining what lighting to use and steps to install LED construction lighting. Several project examples will be cited, with detailed examination of the realized quantitative benefits, challenges overcome and lessons learned to assist attendees with future implementations of LED construction lighting.

2:45 pm
Coffee Break

3:00 pm
Rebuilding TBMs: Are Used TBMs as Good as New?
D. Harding, The Robbins Company, Solon, OH

Much has been made worldwide of the difference in performance between new and rebuilt TBMs. Worldwide, a bias exists that seems to favor new machines, but is the bias warranted? The reuse of machines can, if done to exacting standards, reduce costs and time to delivery while also reducing the carbon footprint. But guaranteeing the quality of TBM rebuilds is another issue—one that seems only minimally improved by the existence of international guidelines.
This paper will discuss the process of machine rebuilds and the use of rebuilt TBMs with performance examples from projects worldwide. It will seek to establish guidelines and recommendations based on real experiences of success in the shop and in the field.

3:20 pm
Assessment and Remediation of Gas Utility Tunnels in Chicago
A. Sivaram and C. Gailey, BLACK & VEATCH, Chicago, IL and C. Hirner, Black & Veatch, Kansas City, MO

Peoples Gas Light & Coke Company (PGL) owns 17 critical utility tunnels located in the City of Chicago, constructed between late 19th century and late 20th century that house gas pipelines. The project includes assessment, inspection and potential remediation of these tunnels and associated pipelines. Initial assessments have been conducted and an order of inspection determined based on risk of failure. This paper discusses this risk assessment process as well as the inspection planning and safety measures required to complete the first two tunnel inspections.

Contracting Practices and Cost – Acapulco

Chairs: S. Swartz, McMillen Jacobs Associates, Glenview, IL
M. Wytrzyszczewski, City of Akron, Akron, OH

1:30 pm

1:35 pm
Tunnel Contracting Practice: One Owner’s State of the Art
E. Dowey, C. Edden, S. McAndrew, G. Schmitt, NYC DEP, Pound Ridge, NY and B. Sozer, McMillen Jacobs Associates

The tunneling contracts issued by the New York City Department of Environmental Protection have evolved significantly over the decades. This paper presents the state of the tunneling contract as utilized for the Bypass Tunnel and includes discussion of: prequalification of contractors, a choice of bid sheets and associated excavation techniques, contract structure, differing site condition, liquidated damages, incentives, mobilization, pay items, bonding and insuring a long contract, the risk process, partnering, GDR and GBR, partially prescriptive tbm specifications, standards for contractor designed underground elements, rolling allowances, probing and pre-excavation grout requirements, segment design, safety, submittal handling, permitting, and metrics.

1:55 pm
Having Difficulty Deciding on Procuring New, Refurbished or Remanufactured TBMs?
D. Ifrim and D. Zoldy, Hatch, Mississauga, ON, Canada

What happens to New TBMs at the end of the project? Most of these machines are recovered and stored by contractors with the hope of an upcoming project, while some are being sold or leased to other contractors or purchased back by the manufacturer.This paper discusses the fate of a new TBM after its intended project use and the outlook for re-employment as a used TBM on future projects.

The paper discussion focuses on the qualitative conditions to be considered in the decision to employ refurbished or remanufactured TBMs, to comply with future project opportunities and requirements. As a backgrounder, the paper will also analyze the ITA recommendations for re-manufacturing and refurbishment of TBMs

2:15 pm
Design/Build Construction in Underground Construction. A Contractors Perspective
S. Hoffman and G. Almeraris, Skanska, East Elmhurst, NY

The Design/Build contract delivery method, where substantial portions of the final design are developed by the Contracting entity, has been around in some form for many years, but the modern form of this approach emerged in the late 20th century. This paper walks thru the original goals and drivers for the development of the modern Design Build approach, and how Design/Build has evolved in the Underground contracting world. It will explore the unique contract related challenges posed by underground risk-both positive and negative. Additionally, the effectiveness of this approach and other forms of Design/Build procurement such as PPP, Progressive Design/Build and ECI will be explored.

Finally, the presenter’s will give their perspective from the Contracting Entity (design/builder) on this methodology along with recommendations.

2:35 pm
Application of Alternative Projects Delivery Methods based on a Risk-Based Probabilistic Approach
P. Sander, RiskConsult, Innsbruck, Austria; J. Reilly, John Reilly International, Framingham, MA and M. Spiegl, RiskConsult, Innsbruck, Austria

Effective cost and risk management is essential for the success of large infrastructure projects, as demonstrated by a long history of cost overruns. In order to achieve cost transparency, risk-based probabilistic approaches are needed to determine the probability that project delivery can be accomplished within cost and schedule goals. In addition to some owners moving to a more collaborative and incentivized project environment, a significant number of owners and agencies are also considering alternative contracting models to deliver their projects. This paradigm shift is driven by the fact that more traditional delivery methods, e.g. fixed price contracts, often fail to meet objectives due to factors which the authors have described in previous papers. This paper describes the mechanics of fixed-price incentive fee firm target (FPIF) contracts, provides a framework to analyze such contracts and demonstrates how FPIF pricing arrangements (pain/gain mechanism, target cost, ceiling cost, etc.) can be applied with a risk-based probabilistic approach. Since, in early stages, the project’s outturn cost can only be estimated using ranges, estimates of potential profit for the contractor and project price for the owner need to be made using a probability model for total project cost.

2:45 pm
Coffee Break

3:00 pm
A Study in the Use of Design-Build for Tunnel Projects
S. Von Stockhausen, Mott MacDonald, San Ramon, CA

Design-build has been steadily gaining traction as a preferred contracting method for large infrastructure projects over the last 25 years. This paper examines the use of design-build for tunnel projects: why owners have chosen to implement it and to what extent they are realizing the benefits. The main perspectives of a design-build project will be explored: owner, engineer working for the owner, contractor, engineer working for the contractor, and construction manager. Based on these perspectives, the paper will discuss what is working well and where there is further opportunity for improvement.

3:20 pm
Progressive Design Build - Coming to a Project Near You?
A. Thompson and J. O'Carroll, Mott MacDonald, New York, NY and T. Kwiatkowski, Mott MacDonald, Iselin, NJ

The water/waste water industry has found progressive design-build (PDB) a good fit in delivering capital project solutions. Owners of tunneling projects are taking a keen interest in this approach for delivery of their projects. What is PDB? Is it just early contractor involvement or another method of project delivery, such as Construction Manager at Risk (CMAR) under another name? Is it a delivery method that fosters better owner-contractor relationships with potentially fewer disputes and greater certainty on the final cost? This paper examines which states allow PDB procurements, key elements of this delivery method and issues and pitfalls an owner and contractor need to understand before entering into a progressive design build contract; how pricing is managed, how risk is allocated and provides examples of tunneling projects using PDB as the preferred contracting method.

3:50 pm
Are Alternative Delivery Methods and Private Financing Ways to Deliver Future Underground Projects in America?
K. Bhattarai, Lane Construction, Plano, TX

In recent years in America there has been expanding usage of full private financing in large underground transportation projects. The increasing popularity of alternative project delivery methods and private financing has provided unique opportunities to overcome chronic funding shortfalls, drive technological innovation, and deliver fast-track quality infrastructure and services to the public. This paper represents recent examples of private financing and discusses challenges and opportunities these innovative project financing and delivery methods bring to the construction industry in terms of technological innovation and the procurement, contractual, legal, and risk management of underground infrastructure projects.


Tuesday, June 18, 2019 | 8:30 am

Drill and Blast – Regency A

Chairs: C. Schoch, Skanska, East Elmhurst, NY
B. McQueen, FKCI

8:30 am

8:35 am
Drill and Blast Construction of Shafts and Starter and Tail Tunnels for the 3RPORT CSO Project
S. Miller, Schnabel Engineering, Sterling, VA; D. Chapman, Schnabel Engineering, Cedar Knolls, NJ; J. Parkes, Schnabel Engineering, Baltimore, MD and M. Lechner and L. Waddell, Lane Construction, Fort Wayne, IN

The 3RPORT Project consists of approximately 25,000 feet of TBM-mined tunnel with finished inside diameter of 16 feet and at a depth of 230 feet, constructed primarily through limestone. The project includes three shafts ranging from 25 to 68 feet in diameter. The TBM will be launched from a starter tunnel extending from a working shaft, with trailing gear extending back through a tail tunnel that connects to the pump station shaft. Construction of these shafts requires up to 170 feet of drill and blast shaft excavation. The starter and tail tunnels will have a combined length of approximately 250 feet and are also constructed using drill and blast methods, with several enlarged sections to accommodate the TBM launch and support equipment. This paper describes the drill and blast construction for these shaft and tunnel elements. This includes the design of the initial rock support consisting of rock dowels and shotcrete for both the shafts and starter and tail tunnels and development of alternative testing procedures for these elements. Procedures for the drill and blast excavation rounds are also presented, including the staging of the blast rounds between the adjacent shafts, details of the blasting including round lengths and perimeter controls, methods used for preventing flyrock out of the shafts, and staging of the work in the starter and tail tunnels. Issues encountered in the field and resolutions for these operations are also presented.

8:55 am
Connecting the TARP Des Plaines Tunnel System to McCook Reservoir
M. White, Black & Veatch, Chicago, IL; C. Scalise and P. Jensen, Metropolitan Water Reclamation District of Greater Chicago, Chicago, IL and C. Hirner, Black & Veatch, Kansas City, MO

The Des Plaines Inflow Tunnel is being constructed to connect the 41km long Des Plaines Tunnel System to McCook Reservoir as part of the Metropolitan Water Reclamation District of Greater Chicago’s Tunnel and Reservoir Plan (TARP). Challenging tunnel and hydraulic design and construction components to this project are being addressed using creative construction sequencing that is necessary to complete live connections to the 10m diameter Des Plaines Tunnel and the McCook Reservoir using an elevated tunnel portal outfall. This paper will provide an update on the tunnel, high head gate shaft and energy dissipation structure construction and the challenges encountered during design and construction.

9:15 am
Applying Lessons Learned and Taking on New Challenges at the Lake Mead Intake No. 3 Low Lake Level Pumping Station Project
J. Hoover, Barnard Construction Company, Inc., Bozeman, MT and E. Moonin, Southern Nevada Water Authority, Las Vegas, NV

As the drought continues in the Southwestern United States, work continues on the Lake Mead Intake No. 3 system with the construction of the Low Lake Level Pumping Station Project in Southern Nevada, USA. The project includes underground drill and blast construction of a 535-foot deep Access Shaft, a large 32-foot wide x 34-foot high Forebay Cavern, and large diameter drilling of 34 each, 91-inch diameter x 500-foot deep well shafts. This paper covers how this critical Project applied lessons learned from previous adjacent underground construction, how alternative and collaborative contracting methods were implemented, and how the challenges of difficult ground were addressed for both the underground drill and blast work and the large diameter blind bored well shafts.

9:30 am
Coffee Break

9:45 am
Luck Stone Leesburg Plant Inter-Quarry Tunnel
K. Wooton, Frontier-Kemper Constructors, Evansville, IN

Luck Stone is the largest family owned and operated producer of crushed stone in the United States. In 1971 Luck Stone acquired the Leesburg Plant in Loudon County, Virginia. The Leesburg Plant has not only played a major part in the recent development of Northern Virginia, but historically shipped rock by rail to Alexandria, Virginia since the late 1800s. In 2017, Frontier-Kemper Constructors was contracted to build the Inter-Quarry Tunnel. The Inter-Quarry Tunnel will connect the Leesburg Plant’s existing East Pit to the future West Pit traveling beneath Goose Creek. Goose Creek is a state scenic river in the Potomac River basin. The tunnel will accommodate both truck traffic and a conveyor belt, providing the East Pit processing plant with diabase and extending the life of mine. The Inter-Quarry tunnel is a 26 ft high by 46 ft wide horseshoe shaped tunnel 1,200 feet in length. The excavation and support of the tunnel utilizes a Sequential Excavation Method (SEM), specifically the New Austrian Tunnel Method (NATM). The drilling and blasting of the tunnel is continuously monitored and the ground support system is adjusted accordingly to adequately support the changing conditions of the tunnel. The tunnel is built using “state of the art“ blasting techniques, ground support systems, monitoring, and equipment. The concentrated suburban environment, environmentally sensitive location, and large size, make the Inter-Quarry tunnel a unique and challenging project.

10:05 am
A Comparison of Emulsions and ANFO Usage in the Horizontal Development Process at El Teniente
R. Castro, Y. Herazo and A. Perez, University of Chile, Santiago, Chile; R. Valdes, Orica, Santiago, Chile and J. Medina, CODELCO, Rancagua, Chile

El Teniente is among the largest underground mines in the world with production of approximately 135,000 tons of copper per day (Baez, 2016). After 112 years of operation, mining is conducted in deeper and more competent rock mass conditions than when the mine was initially opened. The high production rates also require developing a larger number of tunnels in a more efficient way (rapid advance rates at a low cost). For these reasons, El Teniente has defined mine development as a key strategy area for its future, and as such it is continuously looking for technological opportunities to improve safety, efficiency and costs. For many years, ANFO has been the explosive used in this operation. In the last year, emulsions have been extensively tested at El Teniente in lateral developments to technically quantify their benefits. Trial tests were initially conducted in the Diablo Regimiento sector followed by industrial application in the Pacífico Superior sector. Results show that emulsions have many advantages including a smaller volume of poisonous gases and, therefore, less ventilation time required, and fewer boreholes and greater efficiency in terms of advance per round when compared to ANFO. In this article the fundamentals and statistical analysis of the results derived from field tests at El Teniente are presented and compared.

Difficult Ground – Regency B

Chairs: J. Buckley, Jay Dee, Plymouth, MI
A. Mukherjee, WSP, Bellerose, NY

8:30 am

8:35 am
Breaking Through Tough Ground in the Himalayas: Nepal's First TBM
M. Isaman, The Robbins Company, Kent, WA

Years of hard work and planning have paid off at the Bheri Babai Diversion Multipurpose Project. This 12km tunnel is not only breaking through a historically difficult mountain range, but it has also managed to break down the notion, to the people of Nepal, that drill and blast is this only way to excavate the extreme conditions in the Himalayas. This paper will highlight the first TBM in Nepal and how it is managing to bore at an exceptional advance rate of 800m per month, with a high of over 1000m in one month. It will examine what design features of the Double Shield TBM are contributing to the great excavation rates, and how the crew’s operational methods have maximized these results.

8:55 am
Cutting New Ground: TBM Selection for Fort Wayne Utilities Tunnel Works Program
L. Gentile, Black & Veatch Corporation, Indianapolis, IN and T. Short, City of Fort Wayne Utilities, Fort Wayne, IN

The Three Rivers Protection and Overflow Reduction Tunnel (3RPORT) when finished will be one of a few hard rock tunnels excavated using a slurry tunnel boring machine (TBM) in the United States. The 19-foot diameter 25,000 foot long project is part of Fort Wayne Utilities’ Tunnel Works Consent Decree program. 3RPORT is being mined in a competent dolomite that is also a prolific aquifer. Slurry-mode TBM with pre-cast segmental lining selection was based on a detailed analysis and input from pre-qualified contractors. The TBM selection process and lessons learned will be presented with an update on mining and standing segments.

9:15 am
Unexpected Underground Obstructions: Challenges and Lessons Learned from Angeli, the Regional Connector TBM
C. Bragard, Traylor Brothers Inc., Culver City, IN; B. Hadley, Traylor Brothers Inc., Los Angeles, CA and M. Antonelli, Metro Los Angeles, Los Angeles, CA

TBM Angeli bored two tunnels under downtown Los Angeles as part of the LA Metro’s Regional Connector Project. While tunneling the first drive, the TBM encountered several unexpected obstructions: two steel piles (W21X132) and 46 tie backs. While the TBM cuttherhead powered through the steel and literally “chewed“ the obstructions, the machine did not process (or “digest“) the shredded steel as easily: the screws got stuck at multiple occasions and screw number 2 shaft broke. Through great efforts of the tunnel team and fine collaboration with the owner, the project managed to minimize delays and even get ahead of schedule on the second drive. This paper discusses the chain of events related to these obstructions as well as the lessons learned from this experience, both technically and contractually.

9:30 am
Coffee Break

9:45 am
Ground Freezing to Improve Unstable Silty Ground
Shawn Coughlin, Moretrench, Rockaway, NJ and Nate Long, Jay Dee Contractors, Inc., Livonia, MI

Seattle’s Northgate Link light rail project included 3.4mi of twin bore tunnels and 23 cross passages through glacially deposited soil conditions. Ground freezing was used for temporary earth support and groundwater control for construction of several cross passages: five were frozen from street level as part of the base scope, five were frozen from inside the tunnels due to unexpectedly permeable soil, and one was frozen from inside the tunnels due to unstable running silt encountered during pre-probing. This paper discusses the design and construction of the ground freezing system to improve the unstable silty soil at CP-23.

10:05 am
Removal of Large Concrete Obstruction on 96-inch Pipe Ram Crossing of Highway 61 - Neebing, Ontario
J. Carroll, MarshWagner, Westminster, CO; T. Krag and C. Beck, LTL Directional Drilling, Shuniah, ON, Canada and S. Shand, Coogar Sales and Servies, Collingwood, ON, Canada

The 96“ pipe ram crossing of Highway 61 along Jarvis River near Neebing, Ontario was complicated when the contractor, LTL Directional Drilling, encountered a full face of concrete at the head of the 96“ steal casing pipe. Unbeknownst to the owner, designer and contractor of the Jarvis River Crossing project, the original Highway 61 bridge abutment had been left in place when a new culvert and bridge were constructed. This paper/presentation will discuss the teamwork between the contractor (LTL Directional Drilling), owner (Ontario Ministry of Transportation) and blasting coordinator (Cougar Sales and Services) to advance through the 14 feet of concrete bridge abutment and successfully complete the project. Utilizing a non-detonating chemical compound, the contractor was able to get permission from the Ministry of Transportation to blast directly under Highway 61 and do so without a burdensome impact to the traveling public above. It is noted that this stretch of highway is considered a vital link for several communities, while feeding imports crossing from the US/Canadian border (Pigeon River Border Crossing). This paper/presentation further discusses the use of NXBurst Safety Cartridges in trenchless applications when the use of high explosives is not permitted, and the protection of the public and surrounding structures is of the utmost of importance.

10:25 am
Neelum-Jhelum HEP Project: Design & Construction of Underground Works
P. Dickson and F. Tesi, Stantec, Chicago, IL

Located in the Himalaya foothills of northern Pakistan, the Neelum-Jhelum project is a high-head hydro facility generating 970MW by diverting water through a long large-diameter headrace tunnel system, 26-km of which were excavated by drill-blast and 21.5 km by hard rock TBM. All told, the hydraulic tunnels and the various access tunnels serving the large underground powerhouse and surge facilities, add up to a total length of large-diameter tunnels on the job of 67.6 km (42 miles). Design and construction of the tunnel system and powerhouse cavern had to manage many severe technical challenges, including complex geology, active faulting, high cover (up to 1900 m), anomalous rock stresses, deadly rock-burst occurrences, and massive groundwater ingress under high pressure. The project also faced many non-technical issues causing delays and inefficiencies. The paper describes these challenges and how they were overcome by the design and construction staff, in many cases by use of novel techniques and approaches - such as innovative methods to obtain in situ rock stress data to determine areas of tunnel requiring steel-lining, systematic high-pressure consolidation grouting to improve rock mass modulus and reduce permeability, applying common-sense approaches in instrumentation and rock support to reduce dangerous rock burst hazard, and methodical 2-D and 3-D numerical modeling of cavern complex using actual deformation data to check and validate design during construction.

10:45 am
Challenging Geology, Blacklick Creek Sanitary Interceptor Sewer Project in Columbus, OH
E. Alavi, Jay Dee Contractors, Inc., Livonia, OH and E. Whitman, Michels Corporation, Blacklick OH

The City of Columbus Blacklick Creek Sanitary Interceptor Sewer Project (BCSIS), located in northeast Franklin County, Ohio, includes 6.9 km of sewer tunnel. This project also requires the excavation of two shafts at the launch point of the TBM run, 6 intermediate shafts, and two shafts at the receiving point of the TBM. A joint venture of Michels Corporation and JayDee Contractors, Inc. (Blacklick Constructors, LLC) is constructing this project. The tunnel is being excavated using a Herrenknecht EPB TBM. This paper summarizes the preparation work that has been done prior to the launch of the TBM in addition to the methodology that has been utilized to successfully mine through the diverse geology of this project.

New and Innovative Technologies – Regency C

Chairs: B. Messina, Skanska, East Elmhurst, NY
A. Hingorany, Traylor Bros., Inc., New York, NY

8:30 am

8:35 am
Smart Office; A Data-driven Management Tool for Mechanized Tunneling Construction
k. Jahanbakhsh and J. Kabat, The Lane Construction Corp., Cleveland, OH and R. Bono, Salini impregilo, Cleveland, OH

Mechanized tunneling construction with TBM is among the most innovative areas in the construction industry, however, tunnel construction process remains severely under-digitized. While vast data is recorded by construction equipment (e.g., TBM, conveyor system) and human interaction (e.g., site engineers, operators), leveraging the power of data to increase productivity and improve the construction process is overlooked. In this paper, the concept of a unified analytics center to gather, integrate, and analyze data from disparate databases on a construction site and then contextualize this information into a visual, meaningful representation provides a robust tool to enhance instant, and far-off decision-making for all levels of site and office personnel is presented. Dugway Storage Tunnel project is considered as a case study. Throughout the construction period of the tunnel, vast quantities of data from TBM sensors is pulled out directly from TBM’s PLC. Data is then pushed into Power BI, which is an analytics service provided by Microsoft. This system connects the project personnel (e.g., Project manager, Construction manager, Project engineer, and site Engineers) to a broad range of data via easy-to-use dashboards, interactive reports, and meaningful interactive visualizations that bring data to life.

8:55 am
High-speed 3D tunnel inspection
H. Kontrus, Dibit Messtechnik GmbH, Innsbruck, Austria

In tunnel assessment, the trend is towards comprehensive 3D measurement combined with high quality image texture to quantify damage to the tunnel surface and to document the building stock. The faster such measurements can be made on site, the lower are the tunnel block times. The costs for the operating companies can be significantly reduced as well as the personnel efforts and risks of accidents. Furthermore, tunnel safety is increased due to faster test cycles which result in a more comprehensive overall monitoring. Dibit has developed a photogrammetric high-speed 3D measuring system, which is unique worldwide. This presentation introduces the technique of the novel measuring system and illustrates the quality of the measurements based on conducted projects.

9:15 am
Tunnel Survey Control in Small Segmentally Lined Tunnels
P. DeKrom, Michels Corporation, Blacklick, OH and E. Whitman, Michels Corporation, New Berlin, WI

The smaller the diameter of a tunnel, the greater the challenges, particularly from a survey standpoint. Usually tunnels in the 3 meter (10 ft.) inner diameter range extend for no more than a few thousand ft. to about a mile and typically have design tunnel alignments (DTA) with a minimal amount of curves. The Blacklick Creek Sanitary Interceptor Sewer (BCSIS) Tunnel Project in Columbus, Ohio, offered numerous survey challenges as the tunnel extended 6.88 km (4.3 mile) and had 13 curves, some with radii of less than 335 meters (1100 ft.). To ensure the stringent accuracy requirements of the project were met, Blacklick Constructors, LLC implemented high accuracy survey techniques such as precision total stations, redundant observations, Control checks at drop shafts, as well as implementing DMT Gyromat 5000 gyro-theodolite high-order gyro-azimuth observations.

9:30 am
Coffee Break

9:45 am
Artificial Intelligence Technique for Geomechanical Forecasting
J. Merello and M. Allende, Skava Consulting, Santiago, Chile and P. Cofre, MetricArts, Santiago, Chile

Rock conditions are evaluated after every blast, performing a rock mass classification. However, no person can see beyond the face. There are three methods most commonly used for this purpose: core drilling, measurement while drilling and probe holes. Artificial Intelligence (AI) is the simulation of human intelligence processes by machines. In this project machine learning techniques, a type of AI, were applied to geotechnical information from probe hole drilling and face mappings, in order to find patterns and inferred functions based on data used for training. Information from both sources had to be standardized, labelled, organized and stored in a way to be easily accessed by the machine learning method. The model only learns from that training data, it is understood that non-experienced situations cannot be predicted. Because of this, it was assumed that every project would need its own training process. A testing tunnel was considered, 1692 registers were used to train a model, and 423 registers were used as test set, all from the same tunnel. Once the model was trained, it was used as a forecasting tool during the performance of new Probe Holes. Results show that the model has an accuracy of +85% forecasting rock mass classification beyond the face in a way that is suitable for advising a decision maker.

10:05 am
The Expanding Capabilities of Microtunneling Demonstrated in Washington DC
T. Brown, Bradshaw Construction Corporationm, Eldersburg, MD

DC Water is improving water quality in Washington DC by replacing aging pipelines. The Oregon Avenue NW Sewer Rehabilitation project was constructed by Bradshaw Construction to replace and improve sewers in Rock Creek Park and Bingham Drive. Of the project’s 4,300 feet of new 24“ sewer, 2,700 feet was installed by microtunneling through the variable rock conditions at up to 90’ deep. Work areas were particularly challenging as the project was located between a quiet, residential neighborhood and Rock Creek Park. Access had to be maintained for residents, emergency services and visitors to the National Park. To minimize public impact, Bradshaw reduced the seven designed tunnels to three including a single 1,860’ drive and a 430’ S-curve with a 625 foot radius. Both drives were record setting for rock microtunneling the in United States for the longest and the first curved drives, respectively. The collaboration and flexibility of the Oregon Avenue team allowed the project to show how far we can push the push the capabilities of microtunneling.

10:25 am
Sandwich Belt High Angle Conveyors Exclusively at Paris Metro Expansion
J. Dos Santos, Dos Santos International LLC, Marietta, GA

Muck disposal from the largest TBMs (Tunnel Boring Machines) is now predominantly by conventional trailing conveyors. The large continuous volumes must be elevated to the surface then conveyed and discharged at a holding area, to be removed to permanent fill locations.

For high volumetric rates the elevating systems to the surface have been pocket belts and sandwich belt high angle and vertical conveyors. The simplicity of the pocket belts, hanging vertically between the lower and upper terminals has been compelling. They have the disadvantage however of great difficulty in fully discharging the muck from the pockets. The sandwich belt systems on the other hand suffer the complexity of equipment, idler rolls that must be accessed and occasionally replaced throughout the beltline. The resounding advantage however is that sandwich belt high angle conveyors use conventional smooth surfaced belts that discharge the material completely as they can be scraped clean. The very sticky muck to be excavated at the Paris Metro Extension project led the client to specify the exclusive use of sandwich belt high angle conveyors for their vertical continuous haulage requirements. The present writing describes how Dos Santos International provided two (2) DSI GPS sandwich belt high angle conveyors for the Paris Metro extension and how they solved the daunting challenges of handling the sticky muck.

Design/Build Projects – Acapulco

Chairs: R. Taylor, Traylor Bros., Inc., Alexandria, VA
D. Mast, AECOM, Cleveland, OH

8:30 am

8:35 am
Permitting in a Design/Build Environment – The Challenges of a 120 years of Design Bid Build Culture
F. Perrone and D. Gaffney, Mott MacDonald, New York, NY

Resource agencies in the United States are not familiar with and do not like structure of Design-Build projects. This paper explores reasons for this and presents possible solutions for improving the permitting process in the Design-Build model. Benefits often attributed to Design-build include innovation in construction methods and faster project implementation. The permitting process has developed over the past 120 years, starting with Section 10 of the Rivers and Harbors Act of 1899. Over the years, new regulations have been implemented on the Federal and State level to improve the environment and protect our common heritage and natural resources. This patchwork of regulations can, however, lead to confusion, especially in the context of Design-Build projects. One of the guiding principles employed by permitting agencies is to review the project in its entirety, and look at all impacts prior to granting a permit. Because of this, the permitting agencies need a “static design.“ In the design-bid-build world, this was easy. The problem with design-build is that the contractor wants to innovate at the same time resource agencies are looking for final designs.

8:55 am
Evolution of Tunnel Eyes Designs Based on Lessons Learned for the Regional Connector Project in Los Angeles
i. hee, E. Mathieu and J. Muhr, Skanska, Los Angeles, CA; D. von Platen, Traylor, Los Angeles, CA and J. van Baarsel, Skanska, Los Angeles, CA

Tunnel Boring Machine Angeli bored two tunnels from Little Tokyo to downtown Los Angeles as part of the LA Metro’s Regional Connector Project. Angeli broke into Hope Station and Flower Cut-and-Cover structure two times at each location within a period of 6.5 months. Ground conditions are similar in both locations enabling fine tuning of tunnel eye designs based on lessons learned. This paper discusses the design and construction of the eyes as well as changes to the TBM mining parameters.

9:15 am
Controlling Risk of Tunneling Projects Implemented by Alternative Delivery Method
N. Munfah and A. Bast, AECOM, New York, NY

The unpredictability inherent in a tunnel project and the accelerated pace of design-build or P3 tunnel projects can result in additional risks, construction delays, added costs and potentially expensive litigation if risk management strategies are not implemented early. Some of the strategies include:

Fair and balanced risk-sharing, early contractor involvement provides opportunities for innovative approaches, collaborative strategies, and risk sharing practice, implementing a comprehensive risk register through design and construction, placing a contingency fund by owners to deal with unknowns, prequalifying the design-builder ensures that the team’s technical expertise aligns with the project needs, and escrow bid document, impartial dispute review board, and partnering help owners and design-builders promptly resolve disputes, claims and controversial issues. This paper addresses risks associated with the alternative delivery methods of tunnels and underground construction from the owner, the contractor, and the designer points of view and provides lessons learned from various recent tunneling projects delivered by alternative delivery method such as the LA Metro Purple Line, the Regional Connector, Thimble Shoal, and Third Hampton Roads. The paper provides guidance to owners, contractors, and designers in implementing risk sharing best practices for tunneling projects implemented by Alternative Delivery Methods.

9:30 am
Coffee Break

9:45 am
Design and Construction of Montreal Express Link Tunnels and Underground Stations
V. Nasri, AECOM, New York, NY; P. Patret, SNC Lavalin, Montreal, Canada; X. De Nettancourt, AECON, Montreal, Canada and T. Mitsch, Dragados, Montreal, Canada

Once completed, the Montreal Réseau Express Métropolitain (REM) will be the fourth largest automated transportation system in the world. For the metropolitan area, the REM also represents the largest transportation infrastructure since the Montreal metro inaugurated in 1966. The proposed solution fosters environmentally sustainable transportation. As a single, integrated transportation network, the REM will be connected to bus networks, commuter trains and the Montréal metro. The REM represents construction costs of approximately 6.3 billion Canadian dollars.

The project consists of 67 km of twin tracks over four branches connected to downtown Montreal. The project includes 26 stations with 3 underground stations in downtown Montreal. One of the underground stations will be built using the NATM method and the 2 others with the cut and cover approach. The project also includes the rehabilitation and enlargement of the Mont Royal Tunnel. This100 year old double track tunnel is about 5 km long. The REM also consists of 3.6 km new TBM tunnel connecting downtown to the Montreal International Airport through saturated soft ground and karstic rock.
The project is currently under construction by a joint venture of SNC Lavalin, AECON, Dragados, EBC, and Pamerleau and the final design is being performed by a joint venture of SNC Lavalin and AECOM. This paper presents the design and construction aspects of the underground elements of this mega project.

10:05 am
DC Clean Rivers Project: We Built Miles of Tunnels … Now What? - How to Get the CSOs into the Tunnels in an Urban Environment
R. Hashimee, EPC Consultants, Washington, DC; A. Ucak, McMillen Jacobs Associates, Washington, DC and M. Wone, District of Columbia Water and Sewer Authority, Washington, DC

The District of Columbia Water and Sewer Authority is implementing its $2.7B Clean Rivers Program to control combined sewer overflows to the Anacostia and Potomac Rivers. The Program consists of large diameter tunnels and a number of diversion facilities to be constructed under a very tight consent decree schedule, in an urban environment, and in and around 100 years old live sewers. This paper focuses on the challenges and the lessons learned while constructing diversion facilities at DC Water’s Main and O Construction Site, contracted using a combination of two different delivery methods to successfully meet the Consent Decree for healthier waterways in the Capital.

10:25 am
Design and Construction of NBAQ4 Water Transfer Scheme
B. Henry, GHD, Brisbane, Australia

The NBAQ4 project will provide water supply for around seven million residents of Manila and is a critical piece of water supply infrastructure for Manila Water Company Inc. The scheme requires a new 3m diameter precast concrete lined tunnel 7.3km long, driven through very weak volcanic rock and soil. The TBM will be driven from the Balara WTP with an EPB TBM designed to negotiate three 80m radius sections of the tunnel drive. The TBM will be driven into a new water Intake Structure in the La Mesa reservoir and will dock there with the shield left in place. The Intake is a 37m tall gravity based structure with a 6m diameter tower and 3 levels of water intake gates. The 16m diameter base includes a TBM docking soft eye. The Intake is connected to shore by a 150m long access bridge and is constructed within a 32m deep steel pipe pile cofferdam with 30m head of water. The tunneling works are executed from a 55m long mined tunnel in very weak rock with soil like parameters and supported with forpoling, steel ribs and shotcrete. The mined tunnel is accessed via a 40m deep temporary construction shaft and a permanent 30m deep outlet shaft. The shafts are 8 and 9 m diameter and are temporarily supported by oversized secant piles with very tight verticality tolerance of 1:200 to avoid internal ring beams. The Outlet shaft piles are incorporated into a 60m deep outlet tower, half above ground and 8m diameter. The piles are used as shaft support (in tension) during a seismic event with a Maximum Credible Earthquake peak ground acceleration of 0.9g. The design has been completed by GHD across Philippine, Australian and UK offices with construction by NovaBala JV of CMC, Chun Wo and First Balfour.


Tuesday, June 18, 2019 | 1:30 pm

Large Span Tunnels and Caverns – Regency A

Chairs: G. Fairclough, Schiavone Construction, Secaucus, NJ
A. Noronha, Black & Veatch, Indianapolis, IN

1:30 pm

1:35 pm
Rock Load Estimation for Shallow Rock Caverns
C. Stone and K. Moon, HNTB, New York, NY

An empirical method for estimating geotechnical rock loads in shallow mined caverns is presented. The extreme variation of rock loadings on mined cavern linings with highly localized geotechnical conditions requires these underground structures to be designed in probabilistic terms with respect to ground classes, thereby minimizing costs for rock support. The method is based on previously measured rock loading data from final lining instrumentation and empirical geotechnical data from previously constructed mined subway station caverns in Washington, D.C. and New York, correlated with geological data and cavern geometry using the Q index value and scaled crown span equation.

1:55 pm
Construction of First Large Diameter Hard Rock CSO Chamber in St. Louis
C. Haynes, Black & Veatch, Wentzville, MO

The Maline Creek Tunnel (MCT) will be the first large diameter chamber to store combined sewer overflows in St. Louis. The MCT is is a key feature of Project Clear, Metropolitan St. Louis Sewer District’s (MSD) Long Term Control Plan to address sanitary and combined sewer overflows to local streams and rivers. Project Clear’s estimated cost is greater than $4 Billion dollars making it the largest public works project to date for the state of Missouri. The MCT includes the construction of a 40-ft diameter, 12.5 MGD submersible pump station, a 28-ft diameter x 2,700-ft long cavern, a 580-ft long x 6-ft lined connecting tunnel, three deaeration chambers, three intake structures, a shallow connector sewer constructed by pipe jacking, and 1,000 feet of 12-inch to 30-inch diameter near surface sewers. Bids were opened on March 10, 2016. The successful bidder was SAK/Goodwin JV with a bid of $83.3 M dollars. The Engineer’s Estimate was $87.7 M dollars. The project was awarded in May 2016. The contractor mobilized on site in June 2016. Shaft and tunnel excavation has been completed. Concrete lining operations are in progress. The project is allocated 1589 calendar days to complete the construction.

2:15 pm
Use of Spray Applied Waterproofing in Bellevue Downtown Tunnel
M. Leong, McMillen Jacobs Associates, Kirkland, WA

The use of spray applied waterproofing for tunnels in the Unites States is relatively new experience. Historically, PVC sheet membrane was been utilized with varying degrees of success for waterproofing tunnels. Sound Transit deliberately chose the option of using a spray applied waterproofing lining in their most recent project, the Downtown Bellevue tunnel, which is a large diameter SEM tunnel. This paper will discuss the decision to allow the contractor the option of utilizing either spray applied waterproofing or sheet membrane, the testing of the product, required specification revisions, field testing, application and performance of the waterproofing to date.

2:35 pm
Construction Considerations for the Garage Cote Vertu in Montreal
J. Habimana, Hatch, Montreal, Canada

The Montreal Transportation Agency (Societe de Transport de Montreal – STM) is currently constructing an underground storage and maintenance garage that will facilitate daily operations and offer parking spaces for new Azur trains. The project comprises three parallel tunnels of 1200 ft long each, 30 ft wide with a pillar with of 16.5 ft; a 2,000 ft long connecting tunnel to the existing station with will have caverns that have spans as large as 62 ft with very shallow rock cover. The contract requires the use of roadheader to excavate the garage to ensure the stability of the pillars. The project crosses near known major faults. The paper will provide construction considerations for the ongoing construction activities that started in May 2017. Most importantly the paper will focus on Challenges associated with the use of the road header to excavate the tunnels and the caverns regarding the hardness and strength of the rock and multiples intrusions that were encountered. An overview of the predicted vs observed ground conditions will be provided as were as how adaptation of initial support were used to address the difficult fault zones that were crossed several times. Finally the paper will make a summary of lessons learned regarding excavation progress and some contractual aspects.

Hard Rock TBMs – Regency B

Chairs: N. Chen, Jacobs Engineering, Boston, MA

1:30 pm

1:35 pm
TBMs Meeting the Challenge in the Pakistan’s Lower Himalayas
G. PEACH, Multiconsult AS, Oxford, UK

TBMs had not been used in Pakistan for 60 years prior to the construction of the Neelum Jhelum Hydro Electric project. TBMs excavated and lined twin 8.5m diameter, 10.5km long parallel headrace tunnels with overburdens up to 1,870 m with high horizontal stresses. The tunnel construction experienced many challenges including soft ground faults, squeezing ground and rockbursts. The TBMs were introduced to this project to improve tunnel excavation rates and were the only realistic methodology for the portion of the tunnel alignment where adit and shaft access locations were difficult or uneconomical due to high overburden and rugged, inhospitable terrain.

1:55 pm
Rand Park Stormwater Diversion Tunnel – Planning and Designing to Address Stormwater Flooding for Downtown Keokuk, Iowa
M. Khwaja, CDM Smith, Waban, MA; M. Schultz, CDM Smith, Boston, MA; G. Sanders, CDM Smith, Kansas City, MO; D. Schechinger, Veenstra & Kimm, Inc., Coralville, IA and M. Bousselot, City of Keokuk, Keokuk, IA

The Rand Park Stormwater Diversion Tunnel is a proposed 3000 feet long, 10-foot diameter rock tunnel that is being planned and designed to satisfy the consent decree commitments and to manage stormwater flooding for the downtown City of Keokuk, Iowa. At an approximate average depth of 80 ft, the tunnel will be constructed through soft rock consisting of a mix of shale/limestone; convey stormwater under the Rand Park to an outfall discharging into the Mississippi River and will help address combined sewer overflow and flooding concerns. Project is committed to a fast-tracked design and construction schedule to meet the negotiated consent decree deadline. This paper presents a synopsis of the project background, the regional geology and the subsurface conditions, challenging site conditions, evaluation of tunnel alignment/profile and the selection process for the optimal tunnel construction approach.

2:15 pm
Major CSO Project Recovery via Deep Rock Tunneling Expansion
J. Steflik, Black & Veatch, Crestwood, KY; G. Powell and J. Mathis, Louisville & Jefferson County MSD, Louisville, KY

Louisville and Jefferson County Metropolitan Sewer District (MSD) will complete an $850 M, 20-year Integrated Overflow Abatement Plan (IOAP) by the end of 2020 to reduce combined sewer overflows (CSOs) into waterways via an off-line CSO conveyance and storage system located along the Ohio River in downtown Louisville, Kentucky. Originally scoped as four separate CSO basin projects, the Ohio River Tunnel (ORT) developed as challenges were encountered throughout design and construction. Three basin projects were included in the original tunnel design. During construction, a fourth basin was included in the project, requiring development of detailed design documents, subsurface investigation, natural gas exploration program, stakeholder and regulatory engagement, and contract negotiations on an accelerated three month design schedule. The project expands the construction of an approximately a 20-foot ID, 4-mile (previously 2.5-mile) 54-million gallon (previously 37-million gallon) deep tunnel and an integrated deep pump station. Key project elements include six drop structures (previously four) to convey consolidation flows to the tunnel, a downstream pump station shaft, and various tunnel adits connecting the drop shafts to the primary tunnel. The tunnel is located within a densely developed downtown area immediately adjacent to the Ohio River; hence, selection of the alignment, grade and construction methods required careful consideration to minimize disruption to the community and environment. Considering the accelerated design schedule and numerous technical and contractual challenges, successful project completion requires close coordination between MSD, the design team, and the contractor, along with extensive collaboration with numerous project stakeholders and regulatory agencies.

2:35 pm
The Three Rivers Protection & Overflow Reduction Tunnel (3RPORT) – Decision-making during Construction
R. Schuerch, Pini Swiss Engineers, Zurich, Switzerland; E. Tamburri and L. Pizzrarotti, Three Rivers Protection & Overflow Reduction Tunnel, Fort Wayne, IN and P. Perazzelli and G. Moranda, Pini Swiss Engineers, Zurich, Switzerland

The 3RPORT tunnel is part of the Long-Term Control Plan (LTCP) of the City of Fort Wayne (Indiana, USA) having the main goal to reduce the discharge of untreated CSOs (Combined Sewer Overflows) and to improve the water quality in Fort Wayne’s CSO-impacted streams. The tunnel will have a length of 7,480 m, an internal diameter of 4.87 m and will be excavated by means of a slurry TBM. The tunnel will cross carbonate rocks at a maximum depth of 60 m and will run mainly underneath the bed of the Maumee and St. Mary’s rivers. The hydraulic conductivity at the TBM tunnel elevation is expected to be extremely high, making the management of the water inflow during advance and during standstill the most important challenge of the project. As the hydrogeological conditions at the TBM tunnel sections are characterized by high heterogeneity, a deviation between the required operational TBM parameters and the design parameters has to be expected. The present paper describes a decision-making process elaborated in strict collaborations between the Contractor and the Designer for the assessment of the ground conditions and the definition of the tunnelling operations during advance.

Geotechnical Considerations I – Regency C

Chairs: D. Watson, Mott MacDonald, New York, NY
S. Lottie, FKCI

1:30 pm

1:35 pm
Digging Deeper - Supplemental Geotechnical Site Investigation for Parallel Thimble Shoal Tunnel
F. Perrone, Mott MacDonald, New York, NY; S. Kibby and A. Wachenfeld, Mott MacDonald, Westwood, MA and J. Ballesta, Dragados, Virginia Beach, VA

The Chesapeake Bay Bridge and Tunnel (CBBT) is a four-lane bridge – tunnel crossing consisting of a series of trestles and two approximately 1-mile-long tunnels beneath the Thimble Shoal and Chesapeake navigation channels. The CBBT Authority is expanding the existing corridor by building a parallel tunnel under the Thimble Shoal navigation channel utilizing a design build contract. As part of the D/B contract a supplemental investigation was planned and executed to support the new design. This paper explores challenges of working in a marine environment around one of the east coast’s busiest commercial and Naval ports, the rationale behind the supplemental investigation and integration of the data into the design

1:55 pm
Geologic Risk and Underground Construction
P. Nelson, Colorado School of Mines, Golden, CO

Population increase means mega-cities will be growing very fast as "compact cities“ for which surface space becomes a priority and for which underground space will become increasingly important. This creates a particular urgency to make the underground space of the future cheaper to construct and reliable in construction and operational performance. The cost and performance of underground projects is intimately linked to the understanding and management of geologic risk for both construction and life-cycle performance of subsurface facilities. This includes “normal“ uncertainties, but also the expectation that urban growth will extend into increasingly fragile and poor geotechnical environments, and that the projects will involve larger and deeper openings. This paper develops a geologic framework to assess the state-of-practice and future possibilities for improved management of geologic risk, including risk avoidance, new materials and methods, ground improvement, life cycle engineering for sustainability, and better subsurface characterization. Some geologic risks have plagued for centuries, e.g., ground water, shallow cover and weathered rock, subsidence and impact on structures, stresses and stress relief, progressive deterioration. And new risks have arisen associated with new technologies including unexpected stress-driven ground behavior, and design for higher water inflows and pressures, increased depth, and variety of excavated shapes.

2:15 pm
Groundwater Drawdown Effects from the Deep Well Depressurization System at Anacostia River Tunnel's CSO-019 Drop Shaft
P. Asadollahi and Gregory McNulty, Parsons, Washington, DC

The Anacostia River Tunnel with a length of 12,300 feet (2.33 miles) and internal diameter of 23 feet was excavated using an Earth Pressure Balance Tunnel Boring Machine (EPBM) in the hard/stiff clays and silts/sands of the Potomac Formation. This paper presents the design of a depressurization system at the CSO-019 Drop Shaft and shows that the use of laboratory derived properties will result in excessive estimates of settlement. This paper shows that more reasonable settlements can be obtained with pressuremeter data; furthermore, when the predicted settlements are compared to field measurements, it is found that the rapid vertical movement of the ground monitoring points in response to depressurization changes come from settlement or rebound in the aquifer, not the aquitard.

2:35 pm
How to Quantify the Reliability of a Geological and Geotechnical Reference Model in Underground Projects
G. venturini, Schnabel-SWS, Alpignano, Italy; G. Bianchi, GTeam, Torino, Italy and M. Diederichs, Queen’s University, Kingston, Canada

Today GBR and GDR are becoming standard contractual documents in any underground project to describe the expected geological and geotechnical conditions. GBR contains a synthesis of all the acquired geotechnical data listed in the GDR and ultimately provides a geotechnical reference model for the project. Despite this, usually few or no information about the reliability of the model are provided. The article intends to present the R-Index innovative methodology, a quantitative method to evaluate the reliability of the Geological Reference Model through a multiparametric approach and to improve the geological risk assessment. Applied examples from the alpine base tunnels (TELT, BBT) will be presented.

2:45 pm
Coffee Break

3:00 pm
InSAR monitoring of subsidence induced by underground mining operations
S. Del Conte and G. Falorni, TRE ALTAMIRA, Vancouver, BC, Canada

Underground mining activities can produce extensive subsidence at the surface, which in extreme cases can cause production blocks, safety risks and damage to infrastructure. The mapping of the extent and magnitude of ground movement is usually one of the main challenges faced by mine operators and is important for mine planning, operational hazard assessment and to evaluate environmental and socio-economic impacts.
The instrumentation used for surface deformation monitoring in and around mining operations was generally based on conventional survey techniques, providing spatially and temporally sparse measurements. The advent of InSAR significantly changed this scenario by providing a high density, bird’s eye view of the surface movements. Beneficial features of InSAR surface monitoring include:
Provision of information without the need to install ground instrumentation, capability to perform historical ground deformation analyses thanks to the existence of data archives going back to the 1990’s, and millimetric sensitivity to vertical deformation, which allows accurate characterization of the areas affected by subsidence
Recent advances in the satellite space segment and processing algorithms have significantly reduced computational time and the advent of newer satellites with increased spatial resolution and acquisition frequency have increased information density. Near-real time InSAR monitoring is now widely applied in different mining settings to highlight possible incipient movements in areas not visible to in-situ instrumentation. Some case studies of InSAR applied to underground mining worldwide will be shown, highlighting the advantages of combining different InSAR techniques to monitor both slow and fast movements.

3:20 pm
Pump-Storage Plants in Switzerland – Challenges and Solutions
J. Kunzle and B. Gisi, Marti USA, Inc., Los Angeles, CA

What is particularly interesting about Pump-Storage Plants is that they combine the functional requirements of power generation with an array of challenges to build a complex facility above and underground. This is about tunneling in a multidimensional and multidisciplinary working environment. The 1000-MW Linth Limmern Project and the 900-MW Nant de Drance Project in Switzerland illustrate both the importance of site logistics as a prerequisite to performing demanding work in accordance with various contractual commitments and the value of a solution-oriented project management approach when it comes to dealing with interfaces between the different components of a Pump-Storage Plant.

Future Projects – Acapulco

Chairs: J. Caulfield, Jacobs Engineering, Oakland, CA
M. Kendall, FKCI

1:30 pm

1:35 pm
Alexandria Renew Enterprises is now in the Tunnel Business
K. Pilong, Brown and Caldwell, Alexandria, VA; L. Maldonado and C. Feehan, Alexandria Renew Enterprises, Alexandria, VA and J. Jordan, JCK Underground, Inc, Boston, MA

Alexandria Renew Enterprises, the local wastewater agency for Alexandria, VA is implementing a large-scale deep storage and conveyance tunnel program to capture and treat combined sewer overflows from four outfalls in the City of Alexandria by 2025. The preliminary planning and engineering studies include approximately two miles of 12-ft diameter soft ground reinforced concrete tunnel, a ½ mile 6-ft diameter tunnel, five shafts and diversion chambers, a tunneling dewatering pumping station, and odor control facilities. This paper will discuss the technical approach, construction considerations, contract delivery plan and schedule, and challenges of constructing in a historically-significant and densely-occupied urban environment.


1:55 pm
DART D2 Subway Project Development
C. Stone, HNTB, New York, NY; I. Crowe, HDR inc, Dallas, TX and E. Wang, HNTB, New York, NY

The DART D2 Subway Project Development effort in Dallas, Texas is currently proceeding with preliminary engineering to support a Design-Build procurement and implementation. A new locally preferred alternative is the 2.34-mile long Victory-Commerce-Swiss Streets alignment. The alignment includes an at grade station near the Perot Museum, three underground subway stations at Metro Center Station, Commerce Street, and the east end of downtown, and ties into the existing light rail system at Victory and Good-Latimer. This complex project will encounter geotechnical, constructability, and interface challenges during its two-year preliminary design period.

2:15 pm
Bringing a 100-year-old Rock Tunnel into the 21st Century through an Intensive Rehabilitation Project
J. Sketchley, MJA, Oakland, CA; R. Fippin and G. Boyce, McMillen Jacobs Associates, Walnut Creek, CA and D. Tsztoo, San Francisco Public Utilities Commission, San Francisco, CA

The century-old, 19-mile Mountain Tunnel is part of the San Francisco Public Utilities Commission water system. Rather than construction of a new tunnel, an intensive rehabilitation of the existing tunnel will be performed. As part of this work, six outages (starting in 2020) are planned. The major challenge will be performing all the work during 60- and 100-day outages. This paper discusses the components of this rehabilitation project, including defect repairs, contact grouting, cutoff grouting, invert repairs, access improvements, extension of the siphon, and construction of a new downstream flow control facility.

2:35 pm
Unique design challenges of the Central Bayside System Improvement Project Tunnel Connections and Shafts
N. Goodenow, Stantec Consulting, Denver, CO; M. Bruen, Stantec Consulting, Bellevue, WA; S. Robinson, Stantec Consulting, Walnut Creek, CA and M. Deutscher, Jacobs Engineering, Boston, MA

The Central Bayside System Improvement Project is a critical element of San Francisco Public Utilities Commission’s aging, seismically vulnerable combined sewer system. The project is comprised of small and large diameter conveyance tunnels, four deep shafts and several complex and challenging soil tunnel connections. The key challenges include design considerations for underground tunnel connections mined through, under, and around abandoned pile foundations and existing utilities located within San Francisco’s Young Bay Mud and alluvial deposits. Several unique and innovative ideas for design are described including potential liquefaction, lateral spreading, obstructions, protection of sensitive utilities and seismic loading and structure response.

2:45 pm
Coffee Break

3:00 pm
MWRA Metropolitan Boston Tunnel Redundancy Program Project Update
K. Murtagh and F. Brandon, MWRA, Boston, MA

The Massachusetts Water Resources Authority (MWRA) provides wholesale water and wastewater services to over 2.5 million customers in 61 communities in eastern and central Massachusetts with most service communities located in the Boston area. The Quabbin Reservoir and Wachusett Reservoirs, which are the main water sources, are located 65 and 35 miles west of Boston, respectively. A redundant water transmission system exists for approximately 25 miles from the Wachusett Reservoir to the beginning of existing Metropolitan Tunnel System. Together, these tunnels carry approximately 60% of the total system daily demand. With no redundancy to the Metropolitan Tunnel System, partial system shutdowns for planned maintenance of the aged infrastructure or unplanned emergencies cannot take place. The planned Metropolitan Tunnel Redundancy Program is proposed to consist of approximately 14 miles of 10-ft internal diameter deep rock tunnel at an estimated cost of approximately $1.4B. This paper discusses the need for a redundant tunnel system, alternatives considered, current plan, and project outlook.


Wednesday, June 19, 2019 | 8:30 am

Shafts and Mining – Regency A

Chairs: P. Backers, Jay Dee, Livonia, MI
P. Rice, WSP, New York, NY

8:30 am

8:35 am
Structural Design of Large Diameter Shafts for the Coxwell Bypass Tunnel
G. Filinov and T. Lahti, R.V. Anderson Associates Limited, Toronto, ON, Canada

To reduce wet weather flow into Lake Ontario and the Don River watershed, the City of Toronto is implementing the Don River and Central Waterfront Wet Weather Flow Project. The project involves roughly 22km of tunnel, 27 connections and 12 shafts and has been split into five phases that are expected to be completed over the next 25 years. Black & Veatch in association with R.V. Anderson Associates Limited were contracted to perform the detailed design of the first phase of the project, called the Coxwell Bypass Tunnel, which includes 10.5km of 6.3m inner diameter rock tunnel and five large diameter storage shafts within the Georgian Bay Shale rock formation. The five storage shafts range in diameter from 20-22m and are up to 58m deep extending through both soil and rock. The shafts feature a composite roof slab design consisting of pre-cast concrete panels and a cast-in-place concrete topping to aid in constructability. Unique unbalanced soil loading conditions were evaluated at one site to accommodate a planned future development. Large hydrostatic water pressures at the base of the shaft led to the use of an arched base slab design to help resist the uplift forces applied over the long spanning shaft diameters. This paper will provide a comprehensive overview of the unique design conditions and challenges encountered during the detailed design of the shafts, a brief background on the analysis techniques utilized, and a summary of the resultant final shaft design.

8:55 am
Design Challenges of Deep Underground Shafts
R. Jain, WSP, Forest Hills, NY and D. Garcia, WSP, New York, NY

Deep shafts serve varying purposes from egress, tunnel boring machine (TBM) launch to combined sewer overflow. The construction of a deep shaft may similarly involve a broad range of support of excavation (SOE) inclusive of ground freeze, slurry wall, secant piles and sunken caissons. The geotechnical and structural parameters and analyses involved often require unconventional considerations and creative solutions. The installation of shaft structures is often a critical path activity to commence other elements of the project. They include facets of internal structures, high-magnitude temporary loads for TBM launch and constructing a cover. The analyses of these shafts must also account for constructability without compromising efficiency. The design of shaft structures must also account for unforeseen conditions for subsequently constructed elements. The analysis of such structures is undertaken using creative closed-form solutions, soil-structure interaction and innovative finite element solutions.

9:15 am
Design and Construction Considerations for Large Shafts in Hudson River Tunnel Project: Hoboken Shaft
Arman Farajollahi, P. Roy and Y. Jin Park, AECOM, New York, NY

As part of the Gateway Program, the Hudson River Tunnel project is a new tunnel alignment running parallel to the existing North East Corridor (NEC) tunnel, and consisting of various surface structures and tunnels from east of Frank R. Lautenberg station in Secaucus, New Jersey, to existing rail complex at Penn Station New York (PSNY). The proposed profile and alignment of the corridor passes as a bored tunnel under the Palisades area in New Jersey and beneath Hudson River through the Hoboken shaft. The Hoboken shaft will be used to receive the Tunnel Boring Machines (TBM) from the Palisades and launch the Hudson River TBMs. The final shaft configuration will is intended to provide a ventilation shaft when completed. The ventilation fans and equipment will be located directly above the tunnel alignment within the Hoboken shaft. At the surface, the ventilation structure will be extended to include the tunnel ventilation operations. The Hoboken shaft is the division between the excavation in rock and in soil. The internal diameter excavation of the shaft is approximately 110 feet with a depth of more than 100 feet. The shaft bottom is located in a rock and very soft soil mixed face condition. The rock is declining from west to east resulting in founding the shaft base at different rock levels and creating an unbalanced pressure loading.

9:30 am
Coffee Break

9:45 am
Construction of Combined Sewer Overflow 021 Diversion Facilities in the District of Columbia
M. Awad, Aldea Services, Springfield, VA

The CSO 021Diversion Facilities project is part of the District of Columbia Water and Sewer Authority (DC Water) Long Term Control Plan (LTCP). The CSO 021 project is located within the John F. Kennedy Center for the Performing Arts (KCPA) property at its southern end, just north of the Theodore Roosevelt Bridge. This paper will provide an overview of the construction activities and challenges. The project involved the construction of a diversion facility and a drop shaft in soil and rock ground conditions approximately 50 and 90 feet below ground surface, respectively. Construction activities included secant piles support of excavation system, rock curtain grouting, rock blasting, and rock bolting.

10:05 am
SHCST Project – Drop and Vent Shaft Construction SHCST Project
C. Haynes, Black & Veatch, Wentzville, MO

The South Hartford Conveyance and Storage Tunnel (SHCST) is a major component of the Hartford Metropolitan District’s Clean Water Project (CWP). The tunnel will capture and store Combined Sewer Overflows (CSO) from the southern portion of Hartford, CT and Sanitary Sewer Overflows (SSO) from West Hartford and Newington, CT. The project includes 21,800 ft of 18 ft final diameter tunnel, several miles of consolidation sewers, eight hydraulic drop structures and a 50 mgd tunnel dewatering station. This paper describes and the challenges and methods used to construct the drop and vent shafts.

10:25 am
The Role of Mechanized Shaft Sinking in International Tunnelling Projects
P. Schmaeh, Herrenknecht AG, Schwanau, Germany

Tunnelling projects require shafts, either as start and reception shafts for the tunnelling process or for inspection, ventilation and rescue purpose. The current trend towards installations in growing depths is driven by deep sewers to avoid pumping stations and the need to build new installations below existing infrastructure. Inner-city shaft structures demand safe working principles for surrounding buildings and environment, especially regarding potential settlements. In addition, deep shafts need special attention for the safety of the operating personnel. The VSM method procures safety for the surrounding environment and for all personnel. As the water level in the shaft equals the groundwater level outside the shaft, there is no water flow which can cause ground movement. All installations including the lining erection are completed from the surface. No personnel have to enter the shaft until it has reached the final depth and is fully secured. The lining consists of either precast segments or cast in place concrete. As the lining installation is completed on the surface, a high quality installation can be reached. In most cases, a secondary lining is not required. The first VSM equipment was put into operation more than 15 years ago. Today, nearly 80 shafts of up to 85m depth have been sunk worldwide using VSM. This paper will describe the role of shaft sinking in tunnelling projects along with all necessary safety and planning aspects when VSM is being discussed.

Grouting and Ground Modification – Regency B

Chairs: D. Delaloye, Mott MacDonald, Vancouver, BC, Canada
A. Mekkaoui, Jay Dee, Livonia, MI

8:30 am

8:35 am
Differences in Consolidation Grouting Practices Between Near Surface and Underground Applications
A. Bedell, Stantec, Atlanta, GA and B. Crenshaw, Ground Engineering Contractors, Jefferson City, TN

Near surface consolidation grouting, such as dam foundation grouting, and underground consolidation grouting should not follow the same grouting principles. Contrasting methodologies, procedures, and overall general site conditions and space limitations require differences in each process. However, all too often Contract Documents contain language within grouting specifications that dictate near surface grouting processes for use in underground applications. The differences between the two procedures are outlined as well as the governing principles that drive each method. In addition to discussing varying grouting principles, grout mixes, factors affecting cost, and equipment considerations are also discussed in detail.

8:55 am
Quality Control of Secant Piles and Jet Grouting for the Ohio Canal Interceptor Tunnel
S. Worst, Schnabel Foundation Company, Cary, IL and M. Niermann, Schnabel Foundation Company, Sterling, VA

Two circular secant pile shafts were installed along the tunnel alignment for the OCIT project in Akron, Ohio. Verticality and concrete volumes were measured on all piles to verify compliance with the design, which consisted of a finite element model with multiple openings using unreinforced concrete secant piles. Double fluid jet grouting was used at the TBM launch portal to create a soil-cement starting block. Automated grouting procedures and continuous data collection were used with confirmatory borings to ensure quality. This paper will discuss the design, construction and quality control of the secant piles and jet grouting for this project.

9:15 am
Grouting TBM Shotcrete Lining under Challenging Conditions
M. Kizilbash, Stantec, Chicago, IL and G. PEACH, Multiconsult AS, Oxford, UK

Twin 8.5 m diameter, 10 km long parallel headrace tunnels under overburdens of up to 1 870 m with high horizontal stresses were excavated for the Neelum Jhelum Hydroelectric Project located in northeast Pakistan using two main beam gripper Tunnel Boring Machines (TBMs). Both TBMs started headrace tunnel excavation in early 2013 with completion by the first TBM in October 2016 and the second TBM in May 2017. This paper briefly outlines the different zones on the TBM where the shotcrete was installed and some of the issues e.g 1600 rockbursts encountered during construction which led to the need for grouting works to the shotcrete lining. The paper then details the complex sequencing for implementing the grouting works due to limited access and describes the various solutions and grouting methodologies employed to carry out the finishing of the two head race tunnels. Details of quantities used for the Neelum Jhelum project are provided for use as a guideline for similar projects in the future.

9:30 am
Coffee Break

9:45 am
Construction Observations during Pre-Excavation Grouting for the Westconnex Tunnels, Sydney, Australia
D. Oliveira, Jacobs Engineering Group Australia, West Pennant Hills, NSW, Australia; H. Asche, Aurecon, Brisbane, QLD, Australia; J. Raymer, Jacobs, CA and D. Crouthammel, McMillen Jacobs, CA and L. Frylinck and J. Casado

The WestConnex New M5 includes twin four-lane tunnels as drained structures in moderately cemented sandstone. About 1.3 km crosses a faulted zone with large, open fractures beneath a 40m deep paleochannel. Pre-excavation grouting, both from surface and underground, is used to control groundwater inflows and depressurization of the overlying soft sediments. Each program has certain advantages and limitations; their successful combination aims to meet the project criteria while assisting the contractor to meet schedule and reduce costs. This paper focuses on the results of the work; it compares grout takes from both the surface and underground programs to what has been observed inside the tunnels during construction.

10:05 am
Merry Christmas! - Emergency Repair of the PCI-12A Interceptor Collapse in Macomb County Michigan
F. Klingler and Z. Carr, FK Engineering Associates, Madison Heights, MI; E. Bantios, Macomb County Department of Public Works, Clinton Township, MI; L. Urban, Anderson, Eckstein and Westrick, Inc., Shelby Township, MI and N. Kacynski, FK Engineering Associates, Madison Heights, MI

On the morning of Christmas Eve, 2016, a family awoke to creaking and cracking noises throughout their home as a massive sinkhole began to daylight under their basement, as well as the adjacent 5-lane thoroughfare and a major utility corridor serving over a million people. The cause laid 65-feet beneath the ground surface as an 11 foot diameter sewer interceptor that services most of Macomb County had collapsed. Following Christmas Eve and Christmas Day evacuation and efforts to protect the public; measures were immediately enacted which led to emergency construction of a 95 MGD pump station and bypass, a 30’ x 320’x 70’ deep recovery shaft, grouting to stabilize the collapsing sewer, and relining of over 3700 feet of failing interceptor. This paper will provide a case history of this monumental repair, including discussion of the many challenges, such as emergency evaluations using conventional and remote geophysical exploration; design and bidding the emergency repair, addressing numerous unknowns during the repair, and completion of this $75 million repair within about 10 months from the failure.

Ground Support and Final Lining – Regency C

Chairs: R. Ball, Mott MacDonald, Independence, OH
D. Dobson, Barnard Construction, Bozeman, MT

8:30 am

8:35 am
7.93M Open TBM Shotcrete System Improvement and Innovation at China’s Jilin Project
D. Willis, The Robbins Company, Solon, OH and Y.Guo, Robbins China, Shanghai, China

In May 2018, a 7.93 m diameter open gripper (Main Beam) TBM completed the 24.3 km long Jilin Lot 3 tunnel under a maximum overburden of 272.9 m. The tunneling operation for the water transfer project, located in northeastern China, achieved a national record of 1,423.5 m in one month despite challenging conditions. This paper will present an improved, innovative shotcrete system for TBM preliminary lining, developed through experience on previous projects. The shotcrete system, along with other structural design elements and a properly developed ground support program, allowed the TBM to bore successfully in variable hard rock and fault zones. The paper will discuss how the shotcrete system and structural design increased safety and improved performance in a cost effective manner. It will seek to define the variables that allowed the TBM to advance at rapid rates, and will make recommendations for future types of projects that could benefit from the shotcrete system.

8:55 am
Design Diagrams for Fiber Reinforced Concrete Tunnel Linings
A. Nitschke, WSP USA, Washington, DC

The flexural design of Fiber-Reinforced-Concrete (FRC) tunnel linings is typically using a material-specific stress strain relationship (SSR) based on beam tests. The evaluation of beam tests to gain the SSR as well as the calculation of the bearing capacity of tunnel linings using an SSR is work intense and especially the latter typically requires specialized software. Getting quick results for changed input parameters is therefore are challenge. The paper introduces design diagrams that allow in a simple and quick manner to either evaluate beam test results to gain the corresponding SSR or evaluate the bearing capacity of a tunnel lining for a given SSR. For given loading conditions, the diagrams can also be used to evaluate the required material properties, which can subsequently be used to assess the required fiber dosage. Therefore, the diagrams provide a powerful tool for a rough estimation and are considered very beneficial if quick results with very little effort are needed, i.e. during preliminary design stages, the bidding phase, or if the effect of changes of material properties or loading conditions need to be assessed.
The paper discusses the basics of FRC design and how the diagrams were developed. In addition, the paper provides some design examples to explain their use.

9:15 am
Steel Fiber Segmental Linings for Mega TBM’s
T. Ireland and S. Fan Chau, Aurecon, New Zealand, Auckland, New Zealand; H. Asche and J. Muir, Aurecon Australia, Melbourne, Australia and B. Clarke, John Holland, Melbourne, Australia

The use of mega TBM’s with external diameter of greater than 14m is rapidly increasing. Up to 2017, there have been 39 tunnelling projects worldwide using mega TBMs. The 15.6m diameter EPB machine, proposed for the $6.7B West Gate Tunnel Project in Melbourne, Australia, will the 7th largest machine. The segmental linings for such large tunnels traditionally have steel reinforcement, however there are many benefits associated with steel fiber reinforcement. Besides manufacturing cost benefits, reduced damage during construction that has also been observed on many smaller tunnels. The segmental lining for the West Gate Tunnel will be the largest diameter steel fiber reinforced segmental lining. This paper describes the challenges with the design of a steel fiber reinforced segment for a mega TBM including massive ram loads, radial joint performance, cross passage openings and the interfaces with the proposed internal structures.

9:30 am
Coffee Break

9:45 am
Complex Tunnel through the Abutment of the High-Risk Chimney Hollow Dam
A. Ruiz, Stantec, Phoenix, AZ; G. Raines, Stantec, San Diego, CA and A. Wilkes, Stantec, Denver, CO

The Inlet/Outlet Tunnel for the proposed Chimney Hollow Dam will be 2000-ft long, six to 22-ft finished diameter with a 26-ft diameter Valve Chamber, and be excavated through siltstone and sandstone. The 330-ft high asphalt core rockfill dam and reservoir create difficult loading and design requirements for both final lining and grouting. Key design considerations include dam/tunnel integration; grout curtain continuity; large openings with high embankment surcharge loads and 300-ft of water head; and control of seepage along the tunnel below this high-risk dam. This paper reviews design concepts, requirements, and presents an overview of how project challenges were addressed.

10:05 am
North American Tunneling Industry Firsts in the Midwest – The Blacksnake Creek Stormwater Separation Improvement Tunnel
B. Glynn, C. Hirner and K. Christopher, Black & Veatch Corporation, Kansas City, MO; L. Sommers, City of St. Joseph, Missouri, St. Joseph, MO and M. Garbeth, Super Excavators, Inc., Menomonee Falls, WI

The Blacksnake Creek Stormwater Separation Improvement Tunnel intercepts Blacksnake Creek stream and stormwater flows up to 18 cubic meters per second (650 cfs) from the City’s combined sewer system and redirects the flows to the Missouri River through a dedicated stormwater conveyance tunnel approximately 2.0 kilometers (1.2 miles) in length and 2.7 meters (9.0 feet) in finished diameter. Mixed faced conditions of soil and shale bedrock along portions of the tunnel alignment required excavation and initial support methods capable of transitioning between the varying ground conditions. An Earth Pressure Balance Machine (EPBM) was selected to provide better control over the excavation face and reduce risks associated with settlement and groundwater inflows. The particular EPBM used was designed by Lovsuns and manufactured in China by Lovsuns’ parent company, their first EPBM delivered to the North American tunneling industry . The tunnel was lined with precast concrete segments solely reinforced with macro synthetic fibers (Elasto Plastic Concrete BarChip 54 fibers) in lieu of steel fibers or traditional bar reinforcement, another first for the North American tunneling industry , to comply with the American Iron and Steel provisions of the Contract. The project also includes a baffle drop shaft, a separate shorter tunnel underneath active main line BNSF railroad tracks, and an energy dissipation structure. This paper will focus on the design decisions and lessons learned throughout construction including addressing mixed face ground conditions and groundwater during the single pass tunnel excavation and installation of the precast concrete segmental tunnel.

10:25 am
Design Delivery Challenges for a Mega TBM Road Tunnel
J.Muir, Aurecon, Melbourne, Australia; H. Asche, Aurecon, Brisbane, Australia and B. Clark, CPBJH JV

The West Gate Tunnel Project is a major upgrade for Melbourne's connectivity west of the CBD. The project includes a major upgrade to the existing West Gate freeway, new bridge and viaduct connections to the Port of Melbourne and the road network near the CBD, and 2 km of new three-lane TBM road tunnel. The TBM design contains innovations in the cross section which provide major improvements for construction, operations and maintenance. The road is supported by a continuous deck along the tunnel length which allows the hydraulic, mechanical and electrical equipment to be located in space which is accessible at all times. This innovation saves considerable operational cost and provides additional flexibility for construction. The cross passages can now be provided as minimum size jacked boxes, built through a single segment opening. Other innovations include the Egress Out and Under (EOU) - which allows the outbound tunnel to be extended an additional kilometre west of the inbound tunnel, to cross the surface freeway and simplify the ramps. The paper describes the concept and the details of the road deck, cross passages, and EOU design and construction.

Geotechnical Considerations II – Acapulco

Chairs: J. Steflik, Black & Veatch, Louisville, KY
J. Sankar, HNTB, New York, NY

8:30 am

8:35 am
Estimating Groundwater Inflow in Tunneling: A Case History for the Lower Meramec Tunnel, St. Louis, MO
K. Johnson, WSP USA, San Francisco, CA and X. You and Kyle Williams, WSP USA, St. Louis, MO

Estimating groundwater inflow in tunneling projects is one of the most challenging and important elements of tunnel design and construction. For the Lower Meramec Tunnel (LMT) in St. Louis, MO groundwater inflow estimates utilized data from packer tests and long-term aquifer testing to develop hydraulic conductivity estimates for various reaches of the tunnel alignment. Methods of Heuer and Raymer were used for initial inflow estimates and adjustments were made to reconcile two types of tests. The data and analysis suggest the two testing methods for hydraulic conductivity characterization display systematic differences that should be considered in developing groundwater inflow estimates.

8:55 am
Use and Misuse of Geotechnical Baselines to Predict Soft Ground TBM Tool Wear
U. Gwildis, CDM Smith, Bellevue, WA

Cutting tool changes during pressurized-face TBM drives are a significant risk and cost factor. For contractors preparing bids the uncertainty of predicting tool wear can cut both ways, leading to non-competitive bids or to budget issues during construction. Either trend constitutes a risk to cost-effective project execution and avoidance of legal dispute. This paper describes how geotechnical baselines can be used and misused for tool wear prediction. And it tackles the question of baselining the tool wear system behavior that is driven by the geotechnical conditions as much as the contractor’s machine design and mode of operation. A mission impossible?

9:15 am
Writing the GBR So the Contractor Can Understand It
B. Doyle, Stantec, Mequon, WI

The complexity of GBR subject matter can stymie even experienced writers attempting to convey their understanding of subsurface conditions to the reader. A deeply structured approach to presenting GBR content is presented, designed to achieve order and consistency, and to convey relative importance of various parts of the content. The structure features a geological model to identify subsurface variables, a geotechnical model to define the interpretation of subsurface conditions, and a construction model to describe expected ground response to construction. The reader-oriented classic style of non-fiction writing is proposed as a better alternative to writer-oriented analytical style for achieving GBR objectives.

9:30 am
Coffee Break

9:45 am
Innovative Monitoring for Urban Tunnelling
P. Thurlow, Geo Instruments, Santa Paula, CA and G. Frank, Metro, Seattle, WA

Tunneling in soft ground for the Regional Connector transit project in downtown Los Angeles had many challenges including typical risks of damage to buildings and utilities, community disruption, and environmental impact. A considered approach to monitoring structures and ground was required that had to draw on new innovations in the instrumentation industry. As well as structural monitoring, the planning and effects of compensation grouting had to be measured and quantified. Unique measures were taken to start tunneling under existing buildings immediately upon launching the earth pressure balance (EPB) tunnel boring machine (TBM) with very low ground cover. This paper provides an overview of the measures taken to safeguard all assets with particular attention to innovation in wireless instrumentation to control compensation grouting and understand structural response and visualization techniques of inground data that has revolutionized the way that volume loss can be viewed real time.

10:05 am
Optimization of a large-scale rheometer by using computational fluid dynamics modeling in soft ground shielded TBM application
W. Hu and J. Rostami, Colorado School of Mines, Golden, CO

The Earth Pressure Balanced TBM operation requires certain conditioned muck properties such as certain rheology. To date there are few soil conditioning studies that have been conducted from a soil rheology perspective. This paper focuses on the conceptual design and numerical optimization of a large-scale rheometer recently fulfilled at Colorado School of Mines, Earth Mechanics Institute (EMI). A VFD unit was first added, enabling the machine to run at RPM ranging from 0 to 60. Then, four computational fluid dynamics models with four types of propeller, including two three-blade propellers with different pitch angles, one vane shear blade, and an auger bit, were established in Comsol and tested by changing rpm and soil rheological properties. The computed relationships between soil rheological properties and resultant system torques were established. At last, the propeller having the most evident sensitivity of torque with respect to soil properties was selected as the optimized design for further lab testing.

10:25 am
SCMAGLEV – Fast and Innovative Mode of Transportation in the Northeast Corridor - Tunneling Challenges
V. Gall, N. Syrtariotis, and T. O’Brien, Gall Zeidler Consultants, Ashburn, VA, C.Crawford, Louis Berger, Washington, DC; D.Henley, Baltimore Washington Rapid Rail, Baltimore, MD

The Northeast Corridor Superconducting Maglev Project (SCMAGLEV) entails construction of a high-speed train system between Washington, D.C. and New York City, with the first leg between Washington and Baltimore, MD. The system operates using an electromagnetic levitation system developed and deployed in Japan that achieves an operating speed of 500 km/h. SCMAGLEV is an innovative project that will shorten travel times between Washington D.C. and Baltimore to 15 minutes, and connect to New York City in under an hour. In 2018 the FEIS is being developed and the designs advanced to preliminary engineering level. A geotechnical investigation campaign is underway. This paper provides an update on the project and discusses construction of the predominantly soft ground EPBM driven tunnels.



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