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A. Saitta, Egis Tunnels and F. Martin, BG Ingénieurs-conseils The storage of nuclear waste gives rise to a lot of innovative issues for underground space technologies. The nuclear activity of waste generates temperature effects on both the lining and the surrounding rock mass. In order to avoid these unfavorable effects, the number of waste containers is controlled in the gallery section. The galleries section has consequently ranged from a diameter of 4 to 6 meters. However, in the case of intermediate-level nuclear waste, due to the lower temperature, the number of containers in a cross section of a gallery is assumed to be safely increased. Despite technical difﬁculties, a large diameter gallery (typically 12m excavated) seems to be more cost effective. This paper demonstrate the feasibility of such a gallery in the speciﬁc context of CIGEO (French Geological Repository Project for nuclear waste), located in the Bure area in the north-eastern of France. The geology of Bure at the project’s depth (about 520 meters) consists in a quite homogeneous layer of Callovo-Oxfordian argillites (COx argillites). With such an overburden, this rock is known to have a high plastic behavior with signiﬁcant time-dependent effects. These mechanical properties require complex behavior laws in computational modeling used for the design of underground facilities.
22 – 28 APRIL | MOSCONE CENTER | WTC2016 Posters (Continued) Minne Lusa Stormwater Conveyance Sewer Project – Omaha, NE M. Khwaja, COWI NA; D. Poduska, AECOM; P. Donde, PE, COWI NA and T. Wanless, AECOM The proposed Minne Lusa Stormwater Conveyance Sewer is part of the Phase 3 Major Combined Sewer Overﬂow projects to be scheduled as part of the City of Omaha’s Long Term Control Plan (LTCP). The system features a 6,100 foot long, 14-foot inside diameter tunnel to provide for conveyance of separated stormwater from previously completed and future LTCP sewer separation projects to the expanded Storz West and Pershing Detention Basins and subsequently, the Missouri River. The tunnel will operate as a pressurized system and convey ﬂows of up to 2,500 ft3/s resulting from a 10-year, 24 hour storm event.
This paper provides a synopsis of the project with a focus on the overall design aspects related to siting the tunnel alignment in an urban environment, the hydraulic analyses performed to choose a pressurized system rather than an open channel system, and expected geologic conditions. Tunnel alignment and proﬁle and geological proﬁle are presented, as well as an overview of the construction related impacts considered during design.
Tunnels for the Murum Hydroelectric Project C.A. Jaramillo and S. Hing Ngu, Sarawak Energy Berhad - SEB The Murum Hydroelectric Project is a 944-MW development consisting of a 145 meter high RCC dam, two 2660 meter long, 9 meter excavated diameter upper pressure tunnels, surge shafts, two 950 meter long 7 even meter OD penstock tunnels and a surface powerhouse. The project is located in the eastern section of the State of Sarawak, Malaysia, about 200 kilometer from Bintulu, in the Rajang Fold-Thrust Belt, an Upper Cretaceous to Upper Eocene fold and thrust belt that extends under most of Sarawak.
The Belaga Formation consists of a thick sequence of deep marine sediments currently appearing as steeply dipping strata of thin to thick bedded, ﬁne to medium grained sandstone interbedded with argillaceous rocks, resulting on a “Flysch” type geologic environment. The project pressure tunnels were excavated perpendicularly to these strata resulting on frequent change on rock conditions and behavior, and required rock support. This paper describes the characterization of the rock mass, design of rock support, and incidents during construction. Particularly interesting were convergence issues in Tunnel 1 resulting from Tunnel 2 excavation.
Structural Analysis of Composite Support for the Tunnel Design Considering the Performance of Steel Sets H. Yoo, J. Kim, J. Kim and T. H. Jafri, Hanyang University Steel sets such as H-type and lattice girders are often installed in the tunnels before the hardening of shotcrete to ensure the stability of conventional tunnels in soft ground conditions. While designing the tunnels with the help of numerical analysis, steel sets are not often taken into consideration due to their mostly known function as a temporary support. Only a few studies propose the direct application of composite support in the tunnel design, based WTC2016 | SAN FRANCISCO CALIFORNIA, USA WEDNESDAY 27 APRIL on large-scale experiments and numerical analysis. To assess the structural performance of the composite support consisting of shotcrete and steel sets, large-scale experiments were performed on two types of arch-shaped specimens by applying the combined effects of axial forces and bending moments. Based on the results of experiments, numerical analysis was performed for application in the tunnel design. The crown settlement, axial forces, bending moments, and load distribution in the composite support were analyzed according to different patterns.
Analysis of Tunnel Grouting and Water Pressure Tests in Rampur Hydroelectric Project (412 MW), SJVN Limited, India A.K. Chadha, R.K. Chauhan, M.P. Singh and U. Sharma, Rampur Hydro Power Station Rampur Hydroelectric Project (412 MW) is recently commissioned project of SJVN Limited India and successfully works on principle of tandem operation with already commissioned Nathpa Jhakri Hydro Power Station (1500 MW). The main objective in case of Tunnels constructed especially for hydro projects, which carry enormous quantum of water is that, it should not leak. Moreover, the tunnels which are part of water conductor system should resist the inﬂow of water from the surrounding ground in order to avoid draining of natural water sources and lowering of existing groundwater levels. Lowering of water table may result in subsidence and damage to existing surface structures, loss of capacity of drinking water schemes and in some cases even catastrophic sliding of landmass. Grouting and pre-grouting in tunnels serve three different purposes i.e., Stabilization, Strengthening and sealing of the rock mass around tunnels to avoid leakage of water from tunnels. In present paper, results of grouting methodology adopted during ﬁnal construction stage of RHEP (412 MW) along with the introspection of Water Pressure Tests conducted for determination of the efﬁcacy of grouting were elaborately presented. The process, of contact and consolidation grouting which is respectively followed by water pressure tests along entire reach of HRT (15.177 Km long) were also addressed in detail. Pertaining to the results of water percolation tests (before and after consolidation grouting), it was also attempted to categorize the behaviour of different rock mass classes/ conditions in reference to different quantum of grout intake and corresponding Lugeon values. Importance of planned and dedicated successful grouting procedure adopted in hydropower project at RHEP is also emphasized.
Skewed Portal Approach for Steep Slopes D. Ángel Bulla, Estyma S.A and L. Rosas Sánchez, D2 Consult International The two track road sector between Cisneros-Loboguerrero (having a length of 14 km and 11 short unidirectional tunnels) is a new highway still on construction located along the existing Highway Buga – Buenaventura (Colombia). Due to the steep topography, difﬁcult geological/geotechnical conditions, the traditional portal construction approach was impossible to be implemented in eleven (11) of the twenty two (22) portals. In this speciﬁc project, the skewed portal approach was developed as the optimal and more effective solution. The construction time and costs of portals were reduced in 21 months and 75%, respectively. At the 22 – 28 APRIL | MOSCONE CENTER | WTC2016 Posters (Continued) same time, the natural equilibrium of the slopes was maintained, thus, facilitating adequate safety factors along the useful life of the project. This document pretends to show a detailed design experience (and the construction of the entry portal of tunnel 11 (left).
Experimental Investigation on the Static Shear Stiffness of an Immersion Joint W. Xiao and L. Taerwe, Ghent University and Y. Yuan, Tongji University The static shear stiffness of an immersion joint subjected to combined compression and shear forces is investigated by experiments in a test set-up. To explore the performance of the immersion joint, the compression-shear loads, which are applied on a specimen according to test protocol, are determined based on real design situation. In this test, the main focus is on the steel shear keys and the rubber sealing. For the applied loading schemes, different levels of axial force, corresponding to the water depth of the joint, are considered as well as the changing amplitudes of the shear force. The force-displacement curve is obtained and the hysteresis is observed during the whole test. The joint‘s static shear stiffness is calculated, showing to increase linearly with respect to the magnitude of the axial force.
Moreover, it is found that the rubber sealing has a signiﬁcant inﬂuence on the shear behavior of the joint.
Crossing Fault Zones: Detailed Analysis for Radioactive Waste Repository Design D. Borbély, T. Megyeri and V. Szánto, Mott Macdonald and L. Kovác, Kömérö Ltd.
Upon completion, the Bátaapáti deep underground radioactive waste repository complex (National Radioactive Waste Repository – NRWR) will provide safe ﬁnal disposal for low and medium-level radioactive waste from the Paks Nuclear Power Plant in Hungary.
The waste emplacement is in progress and one of the main concerns related to the development is ensuring a feasible plan is in place for permanent repository closure. Detailed hydrogeological observations and safety assessments revealed that the clay ﬁlled fault zones penetrated with the access tunnels play determinant role in the long-term conﬁnement performance of NRWR, so they need to be plugged. Detailed mechanical analysis and numerical modelling of the tunnel constructed through a fault zone is presented here to gain a better understanding of the rock mass and rock support behavior. The effect of stress reﬂection is demonstrated and its consequences are described in detail. A recommendation is given for tunnel support design in such conditions.
WTC2016 | SAN FRANCISCO CALIFORNIA, USA WEDNESDAY 27 APRIL Assessment of Linning Performance of Tunnels Built in Cemented Fine-grained Stiff Soils J. Manuel Mayoral, D. Vital and D. de la Rosa, National University of Mexico This paper presents a numerical study regarding the loads, and the corresponding damage, taken by the primary and secondary lining of a tunnel built in cemented ﬁne-grained stiff soils. This study aims at establishing more rational design criteria that take into account explicity the lining performance. A 3.5 km long tunnel to be built in a densely populated northwest area of Mexico City, was considered as case study. Series of three-dimensional ﬁnite difference models, developed with FLAC3D, were used to simulate the tunnel construction, and to compute the ground settlements, internal forces, bending moments, and displacements acting both on the primary and secondary tunnel linings. Interaction diagrams were used to study the lining performance. Several advancement lengths, and tunnel covers were considered to establish their impact on the loads transferred to the tunnel lining. A practice-oriented damage criterion for tunnels was proposed based on the interaction diagram analysis.
Underground Space for Oil Mining B. Zietlow and M. Gamal, Brierley Associates In oil ﬁelds that have been depleted with conventional surface oil wells but still contain signiﬁcant reserves, an extraction alternative that has been constructed recently consists of a drilling gallery below the oil-bearing formation at the bottom of a 1,200-ft deep shaft where upward sloping wells are being drilled to allow oil collection by gravity. The gallery is 92-ft diameter with a ﬂat ceiling supported by rock bolts and shotcrete structurally connected to the shaft liner, which doubles as a large tension support element.
A special excavation sequence was implemented for the gallery to maximize arching in the stress above the large diameter gallery.
The gallery was located in competent sandstone, constructed with sequential excavation methods, and designed with a 3D ﬁnite element model. Special consideration was given to optimizing the gallery location to take advantage of the geology for construction and support while giving good positioning to the well drilling equipment.
Planning, Finance and Site Investigation Chair: E. Moonin, Southern Nevada Water Authority, USA ITA Co-chair: H. Parker, ITAPast President, USA 08:30-08:50 Risky Business: Repackaging a Critical Contract to Move a Program Forward C. Purcell, Mott MacDonald and M. Pujdak, AECOM In 2011, MTA Capital Construction (MTACC) issued an Invitation for Bid (IFB) on one of the ﬁnal and most critical contracts of the $10.2 billion East Side Access project. Subsequent to the request, and due to high costs and contractor’s access concerns, this request for bids was canceled and the contract was repackaged multiple times over the course of the next four years.
The repackaging unveiled challenges due to access limitations to the underground alignment. Signiﬁcant analysis was required to manage the interfaces between adjacent contractors; to deﬁne and assign risk due to access restraints and shared work areas;
to coordinate access for personnel, equipment and materials across all overlapping and adjacent contracts; and to evaluate adaptations at the time of Bid to take advantage of scope transfers and value engineered alternatives. This paper considers the complexities in the planning, bidding and management of the repackaging of this critical work.
08:50-09:10 Advanced Planning for Northeast Ohio Regional Sewer District’s Clean Lake Program Yields Cost Savings and Reduces Risks – A Case Study in Balancing Hydraulic Performance and Tunnel Engineering Challenges K. Rotunno and D. Lopata, Northeast Ohio Regional Sewer District; T. O’Rourke and K. Vander Tuig, Wade Trim and D.
Dobbels and R. Vincent, McMillen Jacobs Associates The Northeast Ohio Regional Sewer District (NEORSD) was required under the Federal Clean Water Act and U.S. Environmental Protection Agency’s (U.S. EPA) Combined Sewer Overﬂow (CSO) Control Policy to develop a Long Term Control Plan (LTCP) to reduce or eliminate overﬂows from its permitted CSO outfalls.