Dynamic response analyses of soft soil-tunnel-aboveground frame systems under earthquake

The problem of dynamic interaction between subway tunnels and adjacent buildings under earthquake has attracted much attention and concentration, however, the understanding of the dynamic interaction in soft sites is still insufficient. Taking Tianjin soft sites as an example, the Abaqus finite element software was used to analyze the seismic response of the tunnels-soft soil-above ground frame structure system, and a parametric analysis was conducted from aspects of the distance between tunnel and above ground frame structure, buried depth of tunnel, distance between paralleled tunnels, and natural frequency of the frame structure. The results show that subway tunnels will cause a certain degree of disturbance, about 10% by using the story drift ratio as a measure, to the seismic response of the ground structurel which they pass beneath. The above ground frame structure may amplify the dynamic stress response of adjacent subway tunnels (especially the underpass subway tunnel), but sometimes may also weaken the dynamic stress response. For the adopted model in this paper, the maximum amplification factor of the peak dynamic stress of the lining is up to 80.7%. It is suggested that the adverse effects of ground buildings on the seismic performance of underground tunnels should be taken into account in the engineering design in case of soft sites. © 2020, Editorial Office of Journal of Vibration and Shock. All right reserved.