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 HighlightsGeometrical 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
Highlights
Study on the seismic ground motions and damage investigations in the presence of subsurface openings such as transportation tunnels and pipelines has been highlighted among the most important topics of geotechnical earthquake engineering [80]
A new and fast approach based on a direct half-plane time-domain boundary element method (HP TD-BEM) was applied to analyze the seismic ground response in the presence of twin circular, elliptical, horseshoe, square, and rectangular-shaped lined tunnels subjected to the propagation of incident SH waves
By colliding the seismic waves to the lining of each tunnel, because of their extreme hard material compared to the surrounding medium ( F = 10), their boundaries act like mirror and trap the waves between the top boundary of tunnels and ground surface
Summary
Study on the seismic ground motions and damage investigations in the presence of subsurface openings such as transportation tunnels and pipelines has been highlighted among the most important topics of geotechnical earthquake engineering [80]. A new and fast approach based on a direct half-plane time-domain boundary element method (HP TD-BEM) was applied to analyze the seismic ground response in the presence of twin circular-, elliptical-, horseshoe-, square-, and rectangular-shaped lined tunnels subjected to the propagation of incident SH waves. For this purpose, by using an appropriate sub-structuring process, the models are prepared in two separate parts including a twin-pitted half-plane and a system of twin liners that are assembled on each other. The wave propagation below the surface is illustrated by wave scattering snapshots in different significant times
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