Seismic behavior of subway station in the soft clay field before and after freeze-thaw cycle

Abstract

The artificial ground freezing method (AGF) is becoming increasingly popular in the construction of subway stations surrounded by soft soil foundations. However, the freeze and thaw lead to the deterioration of the soil properties, causing a huge risk to the subway station subjected to earthquakes. Based on the dynamic triaxial test, the damping ratio and dynamic shear modulus of the soft clay before and after the process of freeze-thaw were obtained. Moreover, the finite element model was conducted to investigate the earthquake behavior of the station structure in the unfrozen and freeze-thaw clay fields. The research results illustrate that there exists a significant difference in the characteristics of the ground settlement and structural displacement between these two soft clay fields subjected to the seismic wave with the peak ground acceleration (PGA) of 0.3 g. Compared with the unfrozen clay field, the surface settlement induced by the earthquake in the freeze-thaw clay field is larger. The damage degree of the subway station is more severe in the freeze-thaw clay field.