Effect of earthquake on stability of subway station and ground motions of surrounding rock masses

Abstract

The effect of earthquakes on the stability of the subway station and ground motions of surrounding rock masses, plays a key role in the seismic design of the subway station to avoid severe damage to subway station itself and adjacent structures. Most of the reported cases in the literatures on the effect of earthquake on ground motions focused on the ground motions without considering underground structures. In this study, the effect of earthquakes on the stability of the subway station, and ground motions of surrounding rock masses were investigated by using the Flac3d. The ground acceleration and safety factor of tunnel lining were highlighted. The results of the numerical analysis indicated the presence of a subway station has a great influence on ground motions, especially for the vertical ground acceleration. The ground acceleration increases with the decrease of buried depth. The amplification factor of ground acceleration is about 1.42. It exists an amplification region above the subway station with the width of 15 m. The safety factor of tunnel lining in subway station has a significant decrease in the maximum decrease rate of 67 %. The safety factor of tunnel lining except for tunnel crown and bottom changes periodic. Ground acceleration will induce extrusion or detach between surrounding rock masses and tunnel lining, and the direction of ground acceleration has a great influence on distribution of safety factor. The side wall and arch feet of tunnel lining is the most unfavorable part. Special attention should be paid to the side wall and arch feet of the subway station during seismic design.