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By Shu Fan Chau, Innes Duncan, Harry Asche, Bill Newns

The North Auckland Line (NAL) in Northland, New Zealand, is being upgraded to pass Hi-Cube containers. The line includes many tunnels and bridges which need to be refurbished to improve structural clearances and line capacity. Tunnel 2 along the line, the Makarau Tunnel, has posed special challenges. Opened in 1898, the tunnel suffered multiple collapses during construction and has shown significant distortion during operation. The tunnel has been repaired many times since opening. Successfully enlarging this delicate and distressed structure has involved historical research, advanced analysis and design, and careful construction. The results provide lessons for dealing with brick lined tunnels and poor ground conditions

Jun 13, 2021

By Ulrich Maidl, Jamal Rostami, Ulf Gwildis

Tunnel Boring Machines (TBM) have more or less become the preferred method of tunneling in various ground conditions and Programmable Logic Controllers (PLC) or microprocessors are standard features on TBMs to monitor and record various sensory systems on the machine providing the possibility for machine automation and control. The data collected from these sensory systems and channeled through PLC is stored for real-time analysis or use by the operators. Based on typical construction specifications, part of the information collected in the process is shared with the project management team representing the owner. Machine data automatically acquired during TBM advance is typically processed by specialized software to offer the project team data visualization and evaluation options. Interfacing with Geographic Information System (GIS), Computer-Aided Design (CAD), 3-D geologic model, instrumentation data bases, and Document Management Systems (DMS) allows for developing Building Information Models (BIM) of the tunnel’s as-built condition. Application of Artificial Intelligence (AI) processes such as Machine Learning (ML) have already been used for analysis of data, including performance prediction of hard rock TBMs, and exhibited the potential of big data analytics in improving the productivity of the operations. This paper outlines anticipated disruptive technological advances with implications on geotechnical exploration, TBM operation, face condition tracking, subsurface risk allocation, and claims management in the future.

Jun 13, 2021

By Nicholas Tabor, Norbert Fuegenschuh, Richard Taylor, Jean-Marc Wehrli

The Plymouth Tunnel forms part of the 16-mile long route of the Purple Line Light Rail Project promoted by the Maryland Transit Administration. The tunnel is approximately 1,220 feet in length with a shallow vertical alignment located beneath a residential area. Challenging mixed ground conditions included surficial soils, decomposed Saprolite, and highly weathered to fresh rock requiring the use of the Sequential Excavation Method (SEM) for construction. This paper discusses innovative approaches implemented during construction as well as challenges faced during planning and installation of a spray-applied permanent concrete liner.

Jun 13, 2021

By Michael Schultz, Gregory Sanders

In 2017, the North Texas Municipal Water District (NTMWD) initiated the design of the Sister Grove Regional Water Resource Recovery Facility (SGRWRRF) to provide additional treatment capacity for future population growth within the Lavon Lake watershed. To provide a discharge location for SGRWRRF approximately 4.5 miles of 2.4- meter (96-inch) internal diameter pipeline will be constructed, including 2.3-kilometer (7,800) feet and 487-meter (1,600 foot) long tunnel segments. This paper will discuss the anticipated geology of the two tunnel segments, selection of the tunnel alignment, the anticipated initial tunnel support requirements and other aspects of the project design

Jun 13, 2021

By Mark C. Russell, Charles T. Russell, Brooke Colburn, Parker Bailey, Desiree Bernhard, Kaito Durkee, Tristen Cutshall, Rob P. H. Urselmann

Hypersonic tunnel boring (HTB) uses directed, high velocity projectile impacts to remove rock. HTB is highly independent of rock strength and targets hard, abrasive rock and variable rock environments. This paper discusses history, theory and presents test (2×2 m and .75×.5 m tunnels) field trial results and technical and economic evaluation. The HTB tests are compared against the historic ‘project REAM’ and the concept against tunnel boring machines and drill & blast in design studies for full-scale 12 m and 4.5×5.5 m tunnels. The positive results indicate that under these conditions HTB can replace Drill & Blast and Tunnel Boring Machines.

Jun 13, 2021

By Francesco Chiappalone, Daniele Nebbia, Lance Waddell, Greg Colzani

As part of the 3RPORT Project, a 5-mile tunnel is being excavated underneath the three rivers of Fort Wayne using a 19-foot diameter Slurry Tunnel Boring Machine. The groundwater pressure at the tunnel axis ranges from 4.5 to 5.3 bar. The rock mass hydraulic conductivity is very high with water inflows up to 10,000gpm imposing significant challenges to the project. After excavating 1,550-feet of the TBM tunnel, major leaks between the tailskin and the segmental lining were observed, indicating the potential deterioration of the tailskin brushes and the need for inspection and eventual replacement. The first part of the paper describes the planning of the intervention, including the design of the polyurethane grouting campaign, the procedures developed for the execution and the controls established during construction to timely assess the presence of potential hazards. The second part of the paper focuses on the experience gained during execution and lesson learned to prevent future occurrences of this nature.

Jun 13, 2021

By Mala R. Ciancia

Planned tunnel projects with advanced geotechnical investigations are more frequently being suspended because of changes in funding, politics, or local priorities. Some of these projects are ultimately canceled, some decelerate and stall, some resume after a short pause, and some restart after being mothballed for several years. The restarted project often differs at least slightly from the predecessor project in terms of alignment and design concept. This paper describes approaches to evaluating the quality and completeness of previous geotechnical investigations for a re-activated project, considering technological advances as well as changes in regulatory requirements, contracting approach, and site conditions which may have taken place in the time since the project was suspended.

Jun 13, 2021

By Glenn Mongillo

Discrete Element Method (DEM) software has been successfully used to simulate various machine/soil interactions and provide insight for industries such as mining and bulk material processing. This paper will investigate typical calibration techniques used in particle models for DEM simulation and physical calibration experiments with soft ground TBM cutting tools to incorporate parameters such as tool drag forces that contribute to required TBM torque. With a well calibrated DEM model, it is expected that TBM simulation results will be more meaningful and provide better insight into TBM performance, power requirements, cutting tool placement, and overall cutter head design.

Jun 13, 2021

By Jürg Künzle

The use of the underground space has been a recurring issue in human history, whereas the reasons for building subsurface structures have changed over time. In the decades to come, the world will be marked by a variety of underground projects never before seen. This paper describes a series of characteristic challenges of designing and building underground freight transportation systems, with reference to the example of Cargo sous terrain, a privately funded underground logistics project in Switzerland. It provides an overview of contracting practices that allow these challenges to be addressed with success.

Jun 13, 2021

By Angus Maxwell, Jacob Grasmick

As the tunneling industry continues to adopt Tunnel 4.0, digital twins of the tunnel construction site are becoming standard requirements for tunneling projects. However, the benefits of these remain unproven to many practitioners. The paper discusses the various implementations of digitalization and describes efforts to combine all data types to analyze the relationships between influences, predictions and performance in a single digital platform. This includes data pertaining to investigations, design, construction, monitoring and post-construction asset performance and management. Based on 16 years of global tunneling projects the paper aims to quantify the tangible and intangible benefits of such systems. Using a number of real examples, the paper describes where opportunities were taken and where they went unrealized. Challenges and considerations for both procuring and developing these digital twins are also discussed.

Jun 13, 2021

By Moussa Wone, Martino Scialpi, Colin LaVassar, Carlton Ray

The Potomac River Tunnel (PRT) is the next major phase of the DC Clean Rivers Program. The design-build PRT project includes a 5.5-mile-long, 18-foot-internaldiameter tunnel, seven shafts, and two underground connections to existing structures. Major challenges include tunnel boring machine (TBM) excavation though mixed-face conditions within a buried paleo-channel and an approximately 1,350-foot-long rock/ soil transition zone; construction beneath the elevated Whitehurst Freeway; tunneling beneath an existing luxury residential building and existing transit tunnels with limited clearance; and complex coordination with a variety of federal, regional, and local stakeholders. This paper describes the overall project scope, geotechnical conditions along the alignment, and primary design/construction challenges and mitigations.

Jun 13, 2021

By Tyler Lahti, Peter Borgacci, Mary Jane Ferraro, Prakash Nadesparan

Toronto Tunnel Partners (TTP), under contract to Metrolinx/IO, is constructing new twin rail tunnels under the Highway 401 & 409 interchange to accommodate additional tracks to support the GO Expansion program for future two-way, all-day service. The new tunnels are being constructed using the Sequential Excavation Method (SEM) and utilize a tunnel pre-support system consisting of a series of 800 mm diameter steel pipes to form a pipe canopy. The pre-support pipes were installed with an Auger Boring Machine (ABM) in four separate headings; one heading from each of the tunnel end portals, and two from a shaft in the middle of the highway. To facilitate the auger boring operation, a custom steel reaction frame was required to counteract the thrust from the ABM at the portals, and a temporary shaft structure was installed in a narrow median space of the highway. The installation of the pipe canopy had to overcome challenges including removal of obstructions, alignment issues, and controlling settlements to the highway surface. This paper discusses the purpose of the pipe canopy, design and installation of the temporary shaft and structures to support the auger boring operation, the experience of the contractor during the installation of the pipes, and brief overview of the experience tunneling below the pipes.

Jun 13, 2021

By Thomas Pea, Heiner Kontrus, Jérôme Steinkühler

In tunnel condition assessment, the trend is towards comprehensive 3D measurement combined with high quality image texture to document and quantify damages to the tunnel surface and to create a cohesive data base of the structural conditions throughout its lifespan. The faster such measurements can be made on site, the less it impacts traffic conditions of the highly sophisticated subway systems. The Dibit high-speed 3D scanning system which is based on Photogrammetry and LiDAR technology enables data acquisition in tunnels at a speed of up to 60 mph. Given the high rate of speed the system can operate, tunnel shutdowns can be drastically reduced, and tunnel safety increased. The photorealistic texturing of the 3D-model allows the identification and analysis of smallest material damage (e.g., cracks ≥0.3 mm wide). The publication illustrates technical details and 3D results of the innovative system from measurements that were performed in the subway tunnels of the Bay Area Rapid Transit System in San Francisco, CA (total length 66.23 km).

Jun 13, 2021

By Jamal Rostami, Tala Tahernia

TBM utilization rate is a component of machine performance prediction and critical for developing a reliable estimate of the construction completion time and cost of the tunnel. Estimation of the utilization rate involves identifying and quantifying the time dedicated to each activity in a tunneling jobsite. Ring building is a common activity in TBM tunneling and takes a large amount of tunnel excavation time when using shielded TBMs. This paper concentrates on the effect of tunnel diameter on the duration of downtimes related to ring building and examines the impact of machine diameter on downtimes. For this purpose, the dependency of segment installation time to segment configuration, and also the diameter of the tunnel was investigated. Furthermore, the ring building time for four tunnels with different sizes of diameters and a variety of ring arrangement were analyzed and the relationship between TBM diameter and segment installation time and consequently TBM utilization was evaluated.

Jun 13, 2021

By Julio C. Martinez, Jeffrey L. Rice, Hayden Weschler

This paper details the extensive underpinning required to hold up the 39th street Bridge while demolishing its massive support piers and building a 30ft deep Cut/ Cover RR tunnel beneath it. The underpinning/SOE support required the construction of 16 large hand dug pits 36ft deep that were reinforced and concrete filled. In addition, an extensive steel support system was tied into the bridge super structure. All of the underpinning/tunnel construction was done while a 110ton crane sat directly atop the heavily trafficked – 66 ft. wide bridge. The tunnel excavation, concrete lining and final bridge pier support work will also be presented. All work was done within 5ft of active mainline tracks and that required tight grouting behind all lagging to eliminate any track settlement.

Jun 13, 2021

By Werner Burger

After its first introduction in 2013, Variable Density TBMs have increased their application significantly in mechanized closed mode tunneling. Throughout a variety of successfully completed and ongoing projects since then, Variable Density TBM technology has demonstrated its advantages in a wide range of applications. This paper will present the developments and lessons learned from these projects as well as the future potential of Variable Density TBMs.

Jun 13, 2021

By Paul J. Smith, Eudomar A. Silva, Quang D. Tran, J. Milton Brooks

The Dallas Mill Creek Drainage Relief Tunnel is an 8.04 km (5 mile) tunnel that will provide 100-year flood protection for impacted neighborhoods in the east Dallas area. “Big Tex” is a main beam gripper TBM capable of changing diameters in mid-tunnel to excavate 2.83 km (9,290 ft) of 11.45 m (37.58 ft) diameter tunnel and 5.21 km (17,095 LF) of 9.93 m (32.58 ft) diameter tunnel. Construction began in April 2018 and is anticipated to be completed in 2024. This paper will discuss the challenges and lessons learned during assembly and re-assembly, start-up and mining with “Big Tex.”

Jun 13, 2021

By Ehsan Alavi, Sanjeer Yogendran, Savreet Singh

The Don River & Central Waterfront Coxwell Sanitary Bypass Tunnel Project in Toronto extends 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. This project includes the installation of five intake shafts connected by 10.5 km of 6.3 m internal diameter tunnel and eleven drop shafts and vent shafts, connected to the tunnel by a series of adits. During the excavation of one of five intake shafts (20 m in diameter and 52 m deep), significant volumes of free phase oil and hydrocarbons were encountered. Due to the heavy inflows of the contaminants, excavation was stopped at the transition depth. The initial support of excavation needed to be redesigned, shaft had to be backfilled with CDF and installation of deeper secant piles are in progress to cut off contaminants. This paper outlines the initial plan for excavation as well as the design changes to the plan. The current status of the shaft excavation and lessons learned will be discussed.

Jun 13, 2021

By Alejandro Sanz Garrote, Juergen Laubbichler, Fernando Triana Gracian, Paz Navarro Gancedo-Rodriguez, Andreas Feiersinger

The Combined Sewage Storage Tunnel (CSST) is part of the Ottawa River Action Plan and will greatly reduce the frequency of sewage overflows into the Ottawa River during storms. The project consists of the design and construction of two TBM tunnels running EastWest (EWT) and NorthSouth (NST) along 6.2 km in total, and multiple shafts and support buildings. Contractor Dragados Tomlinson JV (DTJV) was awarded the 169 million CAD construction contract in 2016 and the CSST will be in operation in 2020. Dr. Sauer & Partners (DSP), supported by Intecsa-Inarsa, was responsible for the detailed design of the precast concrete tunnel lining as well as the geotechnical risk management program. This paper addresses TBM selection, critical tunnel sections, geotechnical risk management and rock mass grouting as a geotechnical risk mitigation measure. Successful collaboration of Owner, Owner’s Engineer, Contractor and Contractor’s Engineer led to a safe and cost-effective design and construction

Jun 13, 2021

By Aaron Archer, James Parkes

This paper presents design considerations for the major underground elements of the pending BCRUA Phase 2 Raw Water Delivery System Project. These elements include two Lake Taps; an 8,800 LF, minimum 10-ft OD intake tunnel; a suction chamber with 6 Pump Shafts; a 30-ft diameter, 300-ft deep Main Shaft; a 2,600 LF Transmission Tunnel with 78-inch steel liner; and a 130-ft deep shaft on the Transmission Tunnel. The tunnels and shafts will be excavated through the Glen Rose limestone. The design development included consideration for technical requirements, easements, third party commitments, previous local project experience, and constructability based on contractor outreach.

Jun 13, 2021