2.5D FE-BE modelling of dynamic responses of segmented tunnels subjected to obliquely incident seismic waves

Abstract

Segmented tunnels are widely used nowadays. However, most existing studies on the seismic response of underground tunnels are based on the model of continuous linings, without considering the segment joints. This paper presents a numerical study aiming to investigate the factors that affect the seismic response of segmented tunnels, with a step further than previously, considering obliquely incident seismic waves. The numerical simulation is carried out by a 2.5D coupled finite element-boundary element (FE-BE) model, which can properly simulate the soil-tunnel interaction for obliquely incident seismic waves and predicts both the transverse and longitudinal seismic responses of the tunnel. It is shown that the joint distribution is one of the critical factors that determine the seismic responses of the segmented tunnel, and the influence of the segment joints tends to be more pronounced when they are located near the positions of large transverse bending moments in the tunnel lining. Compared with the homogeneous tunnel, the reduction in the transverse bending moment and axial force of the segmented tunnel is significant, while it is minor in the longitudinal bending moment and axial force, and the effect of the segment joints highly depends on the soil-tunnel relative stiffness. In addition, the influence of the spectral characteristics of the input motions on the tunnel responses is highlighted.