Three-dimensional seismic response of a cylindrical tunnel with voids behind the lining

Abstract

Past experiences in Japan have suggested a high correlation between the presence of voids behind the tunnel lining and seismic damage of tunnels. To confirm this correlation from a theoretical perspective, this study derives three-dimensional elastic solutions for a deep cylindrical tunnel with a void subjected to obliquely incident seismic waves. The three-dimensional seismic response of the tunnel and the effect of voids on the response are investigated. Herein, a void is treated as a partial non-contact boundary between the lining and the ground, with negligible volume. The substructure method and the point-matching method are used to derive the solutions. Numerical results show that the presence of a void does not lead to a large stress concentration on the lining under an oblique-incidence of seismic waves. However, high correlation between large stress concentration on the lining caused by voids before an earthquake and seismic damage of tunnels is suggested. Based on this finding, reinforcement of the lining where large stress concentration has already occurred is crucial for preventing seismic damage of tunnels.