Effect of tunnel depth on the amplification pattern of environmental vibrations considering the seismic interactions between the tunnel and the surrounding soil: A numerical simulation

The amplitude and frequency of seismic waves caused by an earthquake are modified according to the physical characteristics of the subsurface. Further modification is due to soil - structure kinematic interactions between the subsurface medium and the seismic waves. Analysis of ground motion and subsurface propagation of a seismic wave in the presence of an underground structure needs to include appropriate ground input motion parameters. In order to ensure the protection of important engineering structures, and to prevent environmental damage under earthquake excitation, the dynamic response of the vibrating underground structure needs to be carefully analyzed in terms of wave propagation problems. The aim of this study is to evaluate the effects of the amplification on free field motions, including the underground structure, when considering the tunnel-soil interaction, using numerical tools. The 2-D finite element method was used as a numerical model to determine the magnification effect of seismic excitation with various frequencies, on surface vibration, in the presence of a tunnel structure. Results showed that the presence of underground structure amplified the seismic vibrations on the free field and tunnel, depending on the frequency of the external load and the local soil condition.