Numerical study on the influence of near-fault and far-fault earthquakes on a subway station with emphasis to scattering on the wave propagation

Abstract

To improve the design of surface structures built on underground structures to be safe and resistant to earthquake, it is necessary to study the effects of the underground structures on the scattering in wave propagation and the surface ground acceleration. To this end, various parameters must be studied, including input motion, embedment of the structure, and different subway station dimensions. The present study focuses on these parameters by employing a nonlinear cyclic model called ARCS to simulate the shear modulus reduction and damping ratio increase of soil corresponding to the ones given by the user. The variations of the spectral ratio and the affected period range, peak ground acceleration, and peak relative lateral displacement versus the relative distance under near-fault and far-fault earthquakes are presented. The results indicate that different amplification or de-amplification effects at different surface positions were produced at each frequency by appearing a significant influence on the dynamic behavior of ground surface, soil layers, and the surface structure when a subway station is present. A 1.3 times increase in the surface ground acceleration subjected to far-fault earthquakes and a 1.6 times increase in the relative displacement indicated that study parameters have significant influences on the amplification ratio and scattering of the wave.

Keywords

• subway station
• near-fault and far-fault earthquakes
• spectral ratio
• scattering of the wave
• nonlinear cyclic model