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The third phase of the Bagram Drainage System project at Bagram Air Force Base in Afghanistan included construction of a shallow, 540-m long, 1.8-m inside diameter drainage tunnel. The tunnel penetrated mostly stiff to hard clayey and silty soils. The contractor’s Value Engineering Change Proposal (VECP) to use pipe-jacking with a microtunnel boring machine (MTBM) instead of the speciﬁed two-pass Earth Pressure Balance method was WTC2016 | SAN FRANCISCO CALIFORNIA, USA TUESDAY 26 APRIL evaluated and supported using hand calculations. Contractor support was provided throughout the project by providing design reviews and instrumentation monitoring during construction. This paper compares the value-engineering proposal to the speciﬁed method and describes the construction conditions encountered.
15:00-15:20 Disaster Averted after TBM/Active Gas Main Collision: Utilizing Captivating Case Histories to Educate Stakeholders with Regards to Tunneling in Urban Environments M. Dix, Orange County Sanitation District; R. Ball, Mott MacDonald and M. Briggs, Brown & Caldwell Tunnel professionals must educate all stakeholders on the reality that tunnel projects are not 100% devoid of the need for excavations or public inconveniences during both design and construction phases. Competing stakeholder objectives to limit these disruptions must be weighed against the need to mitigate risks and to produce a constructable, operable and maintainable end product. Perhaps the approach we should take with jurisdictional agencies is sharing memorable case studies that bring to life the potential risks so often buried within lengthy risk registers. This paper provides a sobering case study describing what can occur if the presence and/or location of utilities and other obstructions are not fully understood, due to restrictions placed on exploration or mining operations. In this instance, the Tunnel Boring Machine (TBM) encountered a buried concrete structure, followed by rows of abandoned wood piles, before ﬁnally colliding with an active high-pressure gas main under a bustling coastal highway. Multiple project stakeholders imposed tight logistical and other work restrictions, compounding the difﬁculties experienced during the drive. However, the difﬁculties were effectively managed through the project team’s proactive collaboration and communication with everyone involved.
15:20-15:40 Mechanized Tunnelling Driving Toronto’s Big Move Eglinton-Scarborough Crosstown Tunnel Construction (Eclc1-15) D. Liebno, J. Yamashita, O. Nishikokura and M. Sheehan, Obayashi Canada Ltd.
The Eglinton-Scarborough light rail transit (LRT) Crosstown project is a 19km LRT corridor that includes a 10km underground portion, between Keele Street and Laird Drive. The Western tunnel contract (ECLC1-15) includes 6.5km of twin EPB TBM bored tunnels with a
5.75m internal diameter precast concrete segment lining (PCTL), between Keele Street and Yonge Street. This paper will summarize the overall scope of work, the technical challenges faced and innovative solutions developed by the contractor during: Cutterhead interventions in non-plastic soils, gantry crane TBM move across an existing subway tunnel and the logistic constraints faced during the construction of the twin EPB TBM bored tunnel drives.
15:40-16:10 Break 22 – 28 APRIL | MOSCONE CENTER | WTC2016 16:10-16:30 Lessons Learned from EPB and Slurry Tunneling in Glacially Deposited Soils in Seattle, Washington, USA S. Konda and G. Nishimura, The Robbins Company Thousands of years ago massive glaciers carved much of the landscape in Puget Sound, depositing abrasive and granular soils including cobbles and boulders along with layers of clay and sand. Tunneling in this geology – common throughout much of the northern and Midwestern U.S. – is challenging and can be unpredictable. The use of pressurized face tunneling, most commonly with EPBs, has made excavation in this geology more efﬁcient, but difﬁculties still remain. Through analysis of recent projects in Seattle, Washington, USA using EPB technology, the paper authors will draw conclusions as to the best EPB designs and operational parameters for this variable and often difﬁcult ground. Performance data will be analyzed with an eye towards advancements that could further improve EPB tunneling in glacially deposited soils.
16:30-16:50 Crossrail C310 Thames Tunnel – Mixshield TBM Tunneling in Alternating Ground Conditions with Low Overburden A. Rädle, Arup; C. Ashton, McConnell Dowell and T. Aydogmus, Hochtief Engineering GmbH The Contract C310 is part of the current biggest infrastructure project of Europe “Crossrail” which is a major new cross-London rail link project and comprises the construction of the North Woolwich Portal, Plumstead Portal and the twin tube Thames Tunnels with a length of approximately 2.6km. Two MixShield TBMs (Diameter 7.12m) were driving through differing challenging ground conditions (Thanet Sand, Gravels, Flint and Chalk) below the ground water table. The two tunnels were underpassing several listed buildings, sensitive structures, operational railway tracks with low overburden and close to existing subway tunnels in an urban environment. Several additional measures as compensation grouting, micro piles and an intensive monitoring has been carried out to ensure a safe tunnelling process.
Tunneling with Full Face Shielded Machines:
a Study on the Backﬁlling of the Tail Void R. Shah and D. Peila, DIATI, Politecnico di Torino and A. Lucarelli, Itasca Consulting Group, Inc In mechanized tunneling the annular gap between the segmental lining and the surrounding soil caused by tunnel driving, must be backﬁlled almost instantaneously with an adequate grouting mortar. The objective of this research is to perform a fully three dimensional modeled parametric study using FLAC 3D and evaluate the effects of backﬁll grouting on the tunneling performance.
The research focuses on comparisons between different injection materials and state-of-the-art Bi-Component grout and their effects on the settlements on the surface. The research consists of testing a regular situation of tunnel excavation using a shielded machine with face under pressure. The tunnel dimensions and the soil properties are selected as close as possible to the reality and based on Turin Metro case.
WTC2016 | SAN FRANCISCO CALIFORNIA, USA TUESDAY 26 APRIL 17:10-17:30 Properties and Requirements of Two-component Grouts in Mechanized Tunneling B. Youn, C. Schulte-Schrepping and R. Breitenbücher, Ruhr University Bochum The main requirements of two-component grouts are a high workability and sufﬁcient stability against sedimentation with a retention time of more than 72 hours, as well as a rapid strength development immediately after grouting. Component A usually consists of OPC, water, bentonite, and retarding agent. Component B, a liquid accelerator, is added to Component A during grouting at the end of the shield tail. Current investigations on different compositions of Component A showed a high workability lasting for at least 72 hours. The workability could be extended with increasing amount of the retarding agent to a certain degree. An increase of the bentonite content improved the stability of the mix, but had a negative impact on the ﬂowability respectively the workability of Component A. High compressive strengths could be rather achieved by an adapted mixing ratio of Component A and B than by increasing the amount of the accelerator. Thereby, the interactions and compatibility of the selected constituents play an essential role.
22 – 28 APRIL | MOSCONE CENTER | WTC2016 Posters (On display in the exhibit hall during exhibit hours. Authors will be at their poster from 13:00-14:00 for discussion.) Key Technologies of Large Rectangular Pipe Jacking Machine Y. Han and L. Jia, China Railway Engineering Equipment Group Co, Ltd.
The key technologies of a large rectangular pipe jacking machine with dimensions of 10.12m × 7.27m (width x height) include selection of rectangular cross-section cutting modes, analysis on the strength and stiffness of the rectangular shield, integrated control of electro-hydraulic proportional thrust systems and ground conditioning for excavation are presented in detail in this paper.
These key technologies have been successfully applied and veriﬁed on site during tunneling, providing a new concept for the building of large rectangular trafﬁc and pedestrian tunnels in urban areas for the future.
Stabilizing Flowing Sands on the Millwoods Double Barrel Replacement Project: Uniting Academia and the “Real World” from Field to Lab to Field J. J. Brady, ILF Consultants, Inc; C. El Mohtar, The University of Texas at Austin; K. L. Faught, Ken Faught Consulting Services, LLC and C. Hu, City of Edmonton During construction of a 9.5-ft. diameter sanitary sewer tunnel, the City of Edmonton encountered a large pocket of ﬂowing sand that ﬂooded their TBM and caused signiﬁcant surface subsidence, stopping further tunneling by the TBM through this zone.
A unique collaborative effort ensued between the authors representing the city, consulting engineers and academic researchers to develop the optimal strategy for grouting the problematic soils. The site has a layer of very ﬁnd sand between 20 and 30 ft. in depth with ﬁnes contents ranging from 5% to more than 40%. The collaboration extended from requesting additional site investigation efforts to shipping samples to the UT-Austin laboratories for grout testing plus ground and grouting characterization tests resulting in ﬁeld recommendations for a full scale ground improvement program. New research information on the grouting of ﬁne sands along with a collaborative framework for the design of in-situ grouting projects are the key topics presented.
A Mechanized Tunnelling Innovation – Ring Pipe Jacking Method (RPJM) Z. Liu, Y. Bai and A. Cheng, Tongji University This paper presents a conceptual design of an innovative tunnelling method named the Ring Pipe Jacking Method (RPJ) which is conducted by the Ring Pipe Jacking Machine (RPJM). The RPJM consists of a double ring shell which forms a ring section where small interlaced cutter heads or several micro tunnelling machines are assembled to cut soil. Similar to the conventional pipe jacking method, the RPJM also needs a thrust system, a slurry transport system, and a control system. To satisfy the need for large/super large or special section tunnels in future, the RPJM is designed to reduce sharply the excavation face to the annular section, thus enhancing the face stability. Part of the
Simulation-Based Analysis of Maintenance Strategies for Mechanized Tunneling Projects H. Mattern, M. Scheffer, A. Conrads, M. Thewes and M. König, Ruhr-University Bochum In recent years, the development of tunnel boring machines has revolutionized the tunneling industry. The general structure of a tunnel boring machine (TBM) can be described as a multi-component system. To achieve high performance rates, machine elements have to perform reliably. Performance losses and interruptions of the construction process should be prevented or at least, reduced to a minimum. In order to achieve high advancing rates, cutting tools must be in good condition at any time. Furthermore, failure of individual tools might result in increased and faster wear of remaining structural components. For this reason, maintaining and replacing cutting tools is crucial to prevent project delays due to insufﬁcient boring performance. Precise prognoses concerning the prevailing geology are infeasible and thus, efﬁcient scheduling of maintenance actions is challenging. The intention of this work is to analyze different approaches of TBM maintenance in soft ground. Different strategies are analyzed by the use of a simulation approach. Cutting tool condition is regarded as performance limiting factor. The maximum operation time of the cutting tools is determined using the “Soil Abrasivity Index”. A case study serves to show the effects of different maintenance strategies on total project duration.
Effects of Cover Depth on Ground Movements Induced by Shallow Tunnelling M. Ngan Vu, Delft University of Technology & Hanoi University of Mining and Geology and W. Broere and J. Bosch, Delft University of Technology Assessing the impact of underground construction on existing structures in urban areas is an important topic during design. In this paper, the extent of the effect area due to tunnelling is estimated, where existing foundations are inﬂuenced based on the investigation of surface and subsurface settlements. The extent of the areas where building deformations exceed allowable settlements is presented, which will provide a preliminary assessment during design on the risk on existing structures, based on allowable settlement umax and slope of building max. A more accurate impact area of shield tunnelling on nearby pile foundations is proposed.
The Impact of Digitalization and Connectivity on the Tunnelling Industry The Industrial Internet of Things or the 4Th Industrial Revolution, is making strong inroads into the underground space industry, thanks to improved connectivity and reduced cost of digital technology.
In connection with the WTC 2016 in San Francisco the ITA Committee on Technologies, ITAtech, will organize a special session to explore the consequences for and impact on the tunnelling industry from the accelerating digitalization evolution.
In this session a guest speaker from SIGMA, will present a solid view on the topic, discuss ongoing developments, and point out future directions.
After the guest speaker part, selected ITatech Prime Sponsors will give concrete examples of applications in which they have implemented latest technologies related to this topic i.e. Big data management, Monitoring, Measuring, Control, Automation, Machine diagnostics, Maintenance, Safety, Risk reduction and Process optimization.