Seismic ground response by twin lined tunnels with different cross sections

Abstract

Abstract In this paper, the geometrical effects of shallow twin lined tunnels with different cross sections are investigated to obtain the anti-plane seismic ground motion under vertical/horizontal incident plane SH waves. A model of long two-dimensional lined tunnels is established and embedded in a homogeneous linear elastic half-plane by an applied numerical time-domain boundary element approach. In addition to a brief introduction to the formulation of the method, by considering five tunnel sections including circular, elliptical, horseshoe, square and rectangular, the surface response is sensitized to observe the normalized displacement amplitude/amplification ratio. In this regard, the angle of the incident wave and the frequency of the response are also included in changing the response pattern. To illustrate the results in both time and frequency domains, they are presented as blanket charts, snapshots, and three-/two-dimensional diagrams. The results showed that the seismic response of the surface is extremely affected by the geometric parameters of underground tunnels, which can create different conditions on the ground surface with shifting the direction of the wavefront. Article Highlights Geometrical effect of twin horizontally overlapping lined tunnels. Applying a time-domain half-plane boundary element method. Illustrating the response in time and frequency domains. The effect of depth and distance ratios on the seismic ground motion. Propagating vertical and horizontal incident SH-wave type. Graphic Abstract