Response of Long Tunnel in Layered Half-Space under Asynchronous Seismic Shear-Horizontal Wave Propagation

Abstract

The analysis of the internal forces of long tunnels subjected to seismic loading is an important problem in underground engineering. This study is focused on the seismic responses of a circular tunnel in a layered half-space under a longitudinally asynchronous incident shear-horizontal (SH) wave propagation. The tunnel is assumed to be deep in the ground such that the influence of the ground surface is negligible. A one-dimensional numerical procedure for the free-field responses of the layered half-space due to an obliquely incident seismic wave propagation is presented first. Then the soil–tunnel interaction is considered both in the cross-sectional plane and along the longitudinal direction. The internal forces of the tunnel lining are analytically derived considering not only the effect of the cross-sectional shear strain γxy but also the effect of the propagating transverse motion ux along the longitudinal direction. The final semianalytical solution is obtained from the summation of the two responses. The proposed semianalytical procedure is validated by a comparison with the results from dynamic three-dimensional finite-element analyses.