Analyzing the seismic effect on the metro tunnels in response to some known earthquakes

摘要

Studying the effect of earthquakes on the tunnel lining of shallow depths within the soft ground (like the Metro tunnels) can be of great importance in the earthquake-prone regions. In the present study, the effect of three known earthquakes; i.e.: San Fernando (USA), Naghan (Iran) and Tabas (Iran) are illustrated on some presumed tunnel cross-sections to evaluate the seismic behavior of the ground-lining system. The analyses are based on a 2D finite element program and the results are expressed in terms of deformations, strains and the stresses within the lining. Soil properties and lining characteristics are summarized in Table 1. Several parametric computations were carried out to find out the effect of different variables in design procedure as fol-lowings: the tunnel diameter, earthquake acceleration, type of seismograms, thickness of lining, stiffness coefficient, and ground strength properties particularly ground friction angle. As an example of the output results, the computed amounts of the internal forces induced by the aforementioned three seismograms are shown here in Table 2.