A numerical study on the transverse seismic response of lined circular tunnels under obliquely incident asynchronous P and SV waves

Abstract

The numerical analysis of the transverse seismic response of tunnels is an important issue in the design and safety evaluation of tunnel structures, where the spatial variation of earthquake ground motion induced by wave passage effect has been recognized as an important influence factor that cannot be ignored. In this paper, a 2-D transient dynamic finite element modelling technique is applied to investigate the seismic response of two soil-structure interaction systems subjected to obliquely incident plane P and SV waves. Based on the theory of wave input, the incident earthquake motion is modeled as equivalent nodal forces applied on the truncated boundary, and the free field ground response is calculated from the 1-D time-domain finite element method by considering the wave passage effect. The numerical scheme is implemented into the commercial software ABAQUS, and its accuracy is verified by comparing with the analytical solutions of soil-structure interaction problems. Firstly, the verified method is applied to study the transverse seismic response of a circular tunnel embedded in a homogenous elastic half-space under obliquely incident P and SV waves, where the influence of the incident wave type, incident angle, burial depth and tunnel diameter is discussed. Secondly, the response of circular tunnels embedded in a multi-layered non-homogenous elastic foundation is studied, where the influence of tunnel position in the foundation, flexibility ratio between soil and tunnel and stiffness difference of adjacent soil layers in the foundation are extensively investigated. Moreover, comparison is drawn between the tunnel responses in the homogenous and non-homogenous foundation systems, and the importance of conducting asynchronous seismic response analysis of circular tunnels is highlighted.