Tunnels in saturated elastic transversely anisotropic rock with drainage

Yu Tian, Purdue University

Abstract

Tunnel has been recognized as one of the most important underground structures and widely used for a number of infrastructures. Most of the existing analyses of tunnels were based on the assumption of homogeneous and isotropic rock. In reality, however, rock very often exhibits anisotropic properties or is divided by joints that induce anisotropy. In this research, a Finite Element Method was employed to study the behavior of a lined tunnel with permeable support. The goal of this study is to investigate the influence of material properties on the stresses and displacements in liner for a circular tunnel excavated in transversely isotropic rock with drainage at the contact between liner and ground. The analyses were performed based on the following assumptions: (1) Elastic response of rock and liner; (2) The tunnel has a circular cross section; (3) No slip or detachment between liner and rock; (4) The tunnel is placed at depth and below the water table; (5) Plain strain conditions apply along the tunnel generator; (6) Permeable liner; i.e. water pressure behind the liner is zero. After verifying the numerical model by comparing the simulation outputs with results from existing analytical solutions, a parametric analysis has been completed using the Finite Element code ABAQUS. The effect on liner and ground of orientation of anisotropy, stiffness of both ground and liner, drainage condition at liner-ground interface and permeability were explored. It was found that the ground stiffness is the most important parameter that affects stresses and displacements in the liner; permeability has a significant effect on the distribution of water pressure in ground and hence affects the liner response; the drainage at the liner-ground interface induces additional stresses in the liner.

Degree

M.S.C.E.

Advisors

Bobet, Purdue University.

Subject Area

Geological|Civil engineering

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