Damage and failure of underground subway stations under different soil constraint conditions

Abstract

Investigations from past earthquakes have shown that underground subway stations can suffer excessive deformation under strong seismic loads, leading to the damage of critical components and the collapse of structures. This study presents the results of finite element analyses on the seismic damage of underground subway stations installed under different soil constraint conditions. The plastic hinge distribution and damage characteristics of cut and cover double-storey and three-storey subway stations are analyzed using the finite element method software ABAQUS. Combined with the static analysis results of the column sections, a discriminant method for bending plastic hinges is presented. The numerical results show that the collapse of the subway stations begins with the failure of the bottom columns’ bottom sections, which leads to the bending of the plates and the destruction of the whole structure. The bending deformation at the end section of columns has an approximatively linear relationship with the inter-storey drift ratio, and the change in soil conditions shows no apparent influence. The sidewall deformation behavior varies significantly under different soil conditions, and the bending deformation at the bottom section of sidewalls increases along with an increase in the soil-structure stiffness ratio at the same inter-storey drift deformation level. The sidewall bending ductility ratio of the double-storey and three-storey stations at the elastic-plastic drift ratio limit increases by 61.6% and 26.7%, respectively. In addition, the fitting curves between the component bending ductility ratio and inter-storey drift ratio based on the analysis results are also presented. The findings may provide a helpful reference for the seismic performance evaluation and design of underground subway stations.

Seismic Response and Damage Analysis of Large Underground Frame Structures without Overburden

“…Tao et al [13] studied the seismic response law of Y-shaped columns by taking a large-span, double-deck subway station structure of Beijing Metro Line 6 as an engineering prototype; they found that the horizontal seismic response at the top of the forked branch of Y-shaped columns is stronger than in other parts, which manifests with larger stresses than in other parts. Zhang et al [14] considered the effect of different soil constraints on damage in subway stations. Significant differences in the development and distribution of flexural plastic hinges of underground structures with different soil-structure stiffness ratios were derived for the same level of interlayer displacement deformation.…”