A Dynamic Interaction Model for Seismic Analysis of Cylindrical Tunnels

Abstract

A meshless computational model is proposed for seismic analysis of cylindrical tunnels, involving two stages. In the first stage, within the framework of soil-structure interaction (SSI) formulation developed in literature, the analysis is performed in Fourier space. There, the impedance matrices appearing in the formulation are evaluated by the generalized finite difference method (GFDM) together with a perfectly matched layer (PML). For the description of lining, higher-order shell and plate theories are employed. The second stage involves the inversion into time space via the discrete Fourier transform with the FFT algorithm. It is worth noting that the Fourier transform analysis performed in the first stage gives directly the response for the harmonic excitation case. For assessment, the seismic environments generated by SV and P waves in an infinite soil medium, and a half-space are considered for circular tunnels. It is observed, among other, that (i) for even very large wavelength-diameter ratios, pseudo-static values of thrust in lining may underestimate the dynamic values, in particular, as the lining gets stiffer (ii) the results for half-space case deviate largely from those of infinite medium; due to scattering effects between liner interface and top boundary of half-space.