Seismic Response Analysis of Underground Structures

Abstract

The development and utilization of underground space becomes a new era hot issue for civil engineering in the 21st century. Among them, the subway is one of the mean vehicles of people's daily travel, and the seismic performance requirements for its structure is particularly high. In this paper, the real river-crossing subway shield tunnel is the research object, A detailed introduction has made to the river-crossing tunnel model: the meshing, the seismic load input and boundary conditions, material constitutive model. Then, the pseudo-static method and FLAC3D are used to analyze the seismic response of the river-crossing tunnel model, meanwhile, considering a certain dynamic magnification coefficient to reflect the dynamic response of underground structures. In addition, this paper analyzes the river-crossing tunnel does or does not consider the condition of water. Through the above analysis, this paper gets the following conclusions: (1) Under the effect of transverse shear wave, the transverse displacement of the tunnel is bigger, the vertical displacement is smaller; (2) Under the effect of transverse shear wave, the transverse relative displacement at the tunnel top and bottom is the largest. (3) under the seismic action effect, the tunnel has certain residual deformation. Considering the groundwater effect, there are the following conclusions of the river-crossing tunnel: (1) the surface of the soil is quite close from the permeable boundary, pore water pressure dissipation more easily, soil pore water pressure is not easy to dissipate in the depths; (2) The effective stress decreased with the accumulation of pore water pressure; (3) After the earthquake, void water pressure dissipates, effective stress increase.

Keywords: Earthquake damage, underground structure, river-crossing tunnel, dynamic response.