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TBM Tunnels and Alternative Approaches Chair: D. Caiden, Arup, USA ITA Co-chair: E. Chiriotti, ITA WG2 Vice Animateur, France 08:30-08:50 DSU TBM for Vishnugad Pipalkoti – TBM Design Development for Large Diameter Rock Tunnels Under the High Covers of the Himalaya R. Grandori, SELI Overseas Spa Double Shield TBMs were introduced in the market in the early seventies with three main targets: Increase the TBM performances in term of advance per day thanks to the ability to erect a segmental lining simultaneously with the excavation phase, be able to advance through unstable and disturbed rocks under the protection of the shields and provide a ﬁnished tunnel by installing a precast lining as the TBM advance.In 2003 SELI developed the design of the Double Shield Universal (DSU) TBM as an evolution of the original Double Shield TBM design. This new TBM design was targeted to improve: the TBM capability to advance through squeezing/converging rock formations under high cover, the telescopic joint design (allowing by such to operate the machine in double shield mode in very weak rock), the capability of the TBM to investigate and treat the ground around and ahead of the tunnel face. In the same lapse of time Single Shield TBMs, originally utilized for soft ground tunnelling, extended progressively their range of application to mix rocks and ﬁnally to hard rock tunnelling with increasing performances.
08:50-09:10 Comparison of Shear Elements for Cross Passages in TBM-tunnels B. Ring, Maidl Tunnelconsultants When designing segmental lining at a cross passage, modern solutions try to bear the loads transferred around the opening within the rings by using shear elements in the ring joints. Commonly used shear systems providing coupling are cam & pocket, WTC2016 | SAN FRANCISCO CALIFORNIA, USA WEDNESDAY 27 APRIL shear keys, bicones and steel dowels. These solutions have advantages and disadvantages, but most importantly they have limits in their capacity to stabilize the lining at cross passages.
With the help of 3D-FE-analyses for an opening of one segmental ring these different solutions are compared taking various ground conditions into account. As a result the capacity of the individual system is determined. Notice is made regarding the applicability of the system as well as the consequences for the design and the veriﬁcation.
09:10-09:30 Jinhae Geoje Subsea Tunnel TBM Design and Performance Evaluation D. Young Kim, E. Farrokh, K. Chang Hyun and J. Ho Lee, Hyundai Engineering and Construction The Jinhae Geoje gas pipeline tunnel project is the largest (7.8 km) and the deepest (90 m) subsea tunnel in South Korea. This tunnel will house a pipeline to carry natural gas from the mainland to Geoje Island southeast of the country to alleviate the increased demands for natural gas, especially in the winter season. Tunneling is currently underway using two slurry shield TBMs of 3.5 m diameter.
This paper describes the major design elements of the tunneling machines and their performance evaluation. For this purpose, a thorough analysis of geotechnical information was performed to evaluate the tunnel elevation to reduce the risk of tunneling under high water pressure in unstable and permeable rock mass under 9 bar water pressure. TBM speciﬁcation and TBM performance were also analyzed using different methods, including well-known models as well as a rotary cutting machine test developed in house in Hyundai Engineering and Construction Company.
09:30-09:50 Encapsulated Oil Additive Application in Earth Pressure Balanced (EPB) Tunneling – A Case Study L. Mori, Colorado School of Mines; E. Alavi, JayDee Contractors Inc and C. Baratta, T. Dobbs and B. Sullivan, Solazyme Inc Soil conditioning is one of the main factors in successful application of EPB machines in tunneling projects, which involves changing the characteristics of the ground in order to make it suitable for the tunneling process. Selection of the type of conditioner mainly depends on soil type, properties of the tunnel boring machine, and most importantly geological condition. Proper EPB tunneling and soil conditioning in ground above water table is challenging. This was encountered in Northgate Link Extension Tunneling Project in Seattle, WA. In order to improve the tunneling operation, a novel algae-based encapsulated oil was used as a conditioner and as a result the operation of the TBM was improved signiﬁcantly. This paper reviews the traditional soil conditioning measures that were adopted in University Link and Northgate Link projects in Seattle, WA and compares the results with results when using the encapsulated oil additive.
22 – 28 APRIL | MOSCONE CENTER | WTC2016 09:50-10:10 Experimental Study on the Effects of High-concentrated Loads Exerted by TBM Hydraulic Jacks A. Conforti, G. Tiberti and G. Plizzari, University of Brescia and S. Moro, BASF Construction Chemicals Italy During TBM operations, thrust jacks apply high-concentrated forces to the last installed precast segment. These loads generate a disturbed region in the precast segment under the thrust jacks, in which signiﬁcant tensile stresses (deﬁned as splitting or bursting stresses) occur perpendicular to the load direction.
In addition, due to the demand of compatibility, the combined effect of TBM high-concentrated loads determines tensile spalling stresses in the area far from the loads. Therefore, local rebars or ﬁber reinforcement are required in these areas. This paper focuses on the study of the effects generated by high-concentrated loads exerted by TBM hydraulic jacks, mainly in terms of both spalling and splitting phenomena. Experimental tests on small-scale specimens showed that polypropylene ﬁber reinforcement signiﬁcantly enhances both the bearing capacity and the ductility. Moreover, polypropylene ﬁbers resulted in very effective control of compatibility cracks.
10:10-10:40 Break 10:40-11:00 DCCR Case Study on Guidelines for Achieving an Extended Design Life in CSO Projects C. Caruso, Z. Spera and T. Hennings, McMillen Jacobs Associates; J. Kantola, JCK Engineering; R. S. Kinchen Protecht Consulting and W. Levy and M. Wone, DC Water Owners constructing new combined sewer overﬂow (CSO) systems increasingly seek to have project design lives of 100 or more years in response to the growing size, complexity, and cost to construct and operate these systems. However, a codiﬁed and universally accepted approach to achieving this goal in the United States does not currently exist since service life prediction is a relatively new technical ﬁeld. This paper discusses how the 100-year design life requirement was met for the design of tunnels, drop shafts, and diversion structures in the DC Clean Rivers Program (DCCRP). The authors identify some commonly referenced publications, present the testing framework used by the program manager to characterize the CSOs, review the design criteria used to guide the 100-year design life development, and establish guidelines to be considered by program managers and designers when implementing similar extended design life requirements in other CSO control programs.
WTC2016 | SAN FRANCISCO CALIFORNIA, USA WEDNESDAY 27 APRIL 11:00-11:20 120-year Design Lifetime of Plastics S. Lemke, Sika Services AG and M. Eckl and M. Londschien, Sika Technology AG Watertightness is directly related to the durability and serviceability of the concrete lining. Therefore, modern trafﬁc tunnels and shafts (Figure 1) are generally protected against mountain/ ground water and water penetrating through rock ﬁssures by a sealing system, for example with a loose-laid polymeric sheet membrane. Hereby the waterprooﬁng sealing systems must be reliably fulﬁlling their function during the whole service life of the tunnel structure, regularly of more than 100 years. In consequence, the quality and lifetime performance of the waterprooﬁng materials – beside the correct professional and careful installation in a tunnel infrastructure, is of great importance. The challenge for the industry, owners, operators and designers is ultimately the development of qualiﬁcation testing and requirements (acceptance criteria) for products to ensure the design lifetime performance. Hereby the qualiﬁcation procedure is seen as a routine integrated in standards, norms or guidelines, wherein test procedures should cover typical environments for the speciﬁc application ﬁelds.
11:20-11:40 Challenges in the Design of Segmentally Lined Tunnels for Combined Sewer Outfalls R. D. Aradas, J. M. Fernandez, A. Harding and D. Tsingas, CH2M The adoption of tunneled combined sewerage interceptors and outfalls leads to design linings which are often subject to internal pressures that are larger than the external pressures, resulting in signiﬁcant tension loads. The need to meet stringent durability conditions for the normal design life of 100 years often drives client speciﬁcations to require a double pass solution with a cast in situ secondary concrete lining. However, improvements in concrete technology and the need to seek efﬁciency in terms of time and costs, have driven designers to consider single pass segmental linings. The Riachuelo Sanitation project in Buenos Aires is subject to these constraints both upstream and downstream of a sewage treatment plant. This paper describes how the challenges of up to 2 bar pressure differential have been addressed by careful analysis of soil structure interaction to ensure that the full beneﬁt of external ground pressure is realized, resulting in a more optimal design for the constructor both in terms of cost and time.
22 – 28 APRIL | MOSCONE CENTER | WTC2016 11:40-12:00 Inﬂuence of Fibres on the Creep Behaviour of Reinforced Sprayed Concrete C. Larive, CETU ; D. Rogat, Sigma Béton ; D. Chamoley, CETU;
A. Regnard, Asquapro and T. Pannetier, CETU For several decades, the use of ﬁbre-reinforced sprayed concrete (FRSC) has been becoming increasingly widespread, either as a replacement for or in addition to traditional reinforcements.
Macro-synthetic ﬁbres appeared on the market at the same time as metal ﬁbres (in the 1980s), but their use has developed more recently in France, starting in the early 2000s. While their properties are attractive for underground operations, their long-term performance remains the subject of some controversy, particularly with regard to the phenomenon of creep [1-5]. Unfortunately, the many differences of protocol among the studies carried out (materials, metering, spraying equipment and test methods, etc.) mean that, in general, the results cannot be compared. Although several methods have been developed to assess the bending creep behaviour of ﬁbre-reinforced concrete, the majority of them test notched beams resting on isostatic supports. There are currently no standardised test methods adapted to FRSC on hyperstatic supports (as is the case for FRSC used for underground support).
12:00-12:20 Design of Inclined Braceless Excavation Support with Inclined Buttress Applicable to Deep Excavation Y. Shimada, Obayashi Corporation; K. Nishida, Hokuriku Electric Power Company and Y. Okada, S. Sugie, S. Takahashi, T. Terui, K. Oshiro, and Y. Nakamichi, Obayashi Corporation Temporary retaining walls are ordinarily used for tunnel construction work conducted using the open-cut construction method.
Retaining walls in such instances are typically installed vertically.
However, shoring (such as struts and king posts) is required to ensure the stability of retaining walls in cases of excavation work to depths that exceed approximately 4 m. A new design and construction method that focuses on the effectiveness of retaining walls that are installed on an incline was studied with the aim of improving construction workability by omitting shoring. The inclined braceless excavation support (IBES) method, which was developed for use with the inclined buttress method, requires no shoring, even for deep-open-cut construction work and can be applied to deep excavation work on ground with a high groundwater level. This method has been applied at six work sites in Japan in recent years. This paper introduces the IBES design and construction method and presents veriﬁcation results based on the design method, a model experiment, ﬁnite element analysis, and measurements obtained during construction work.
Enhancement of Seismic Resistance of Reinforced Concrete Members Using Embossed Macro-Synthetic Fibers E.S. Bernard, TSE Pty Ltd Reinforced Concrete (RC) members such as beams and columns are usually required to include stirrups to maintain postcrack shear capacity, and some may include stirrups that act as conﬁning steel to maintain structural integrity during a seismic event (eg. NZS3101, ACI 318). To achieve seismic resistance, the spacing between stirrups is usually required to be much closer than is ordinarily prescribed for non-seismically resistant structures. Each stirrup must also fully enclose the longitudinal reinforcement with long end-hooks to ensure that the contained concrete is sufﬁciently restrained during reverse-cycle loading and the reinforcing bars are conﬁned to prevent buckling. The close spacing between stirrups can lead to congestion of reinforcement within members, and can also be expensive to construct due to the labor-intensive nature of steel ﬁxing. A possible alternative to closely-spaced stirrups is the use of ﬁbers to provide restraint and conﬁnement during a seismic event, although this is not yet recognized in codes.
Design of a Large Diameter Gallery for a Nuclear Waste Storage Project R. Plassart and F. Laigle, EDF CIH (Hydro Engineering Center);