Interaction between tunnel and unstable slope – Influence of time-dependent behavior of a tunnel excavation in a deep-seated gravitational slope deformation |
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Affiliation: | 1. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics of Wuhan, Chinese Academy of Science, 430071 Wuhan, China;2. School of Civil Engineering, Wuhan University,430072 Wuhan, China;3. School of Civil Engineering and Architecture, Suzhou University of Science and Technology, 215011 Suzhou, China;4. State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, China University of Mining and Technology, 221008 Xuzhou, China;1. Department of Structural Engineering, Engineering School of São Carlos, University of São Paulo, Av. Trabalhador São-Carlense 400, São Carlos, Brazil;2. Department of Structural Engineering, University of Los Andes, La Hechicera 5101, Mérida, Venezuela |
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Abstract: | A back analysis of old tunnels in an unstable slope context leads to consider several situations of tunnel entering a slope: cross-cutting tunnel to the slope, oblique tunnel to the slope, or shallow tunnel parallel to the slope. Identified pathologies of structures vary depending on these situations. In the context of a shallow tunnel, the tunnel excavation leads to a slope destabilization due to a more or less important deconfinement of the surrounding massif. Construction techniques influence, on one hand, slope surface displacement acceleration, on the other hand, structural damages in the tunnel lining. Nevertheless, the interaction between tunnel and unstable slope depends on the distance between the slope surface and the tunnel lining plot according to the tunnel diameter (D) and on the geological, geomorphological, hydrological and seismic contexts of the slope. This research focuses on different mechanisms of slope instability in a glacial unloading context, especially in creeping contexts, and on damages affecting the structure of tunnels parallel to the slope. Through numerical simulations, the influence of the construction techniques was studied; so was the choice of the tunnel situation, more or less away from the slope surface. Mainly the delay time before tunnel structure implementation) on the damage lining processes, the interaction between tunnel and slope surface displacements and their time evolution have been taken into account for the most critical tunnel situation in the slope. The different situations of tunnel in the slope permit to set in evidence the safety distance from the slope in the context of a slow glacial unloading mechanism. |
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Keywords: | Unstable slopes Tunnels Damages Numerical simulations Parametric studies Interaction tunnel-ground Time-dependent behavior Glacial retreat Creep |
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