Jordan Journal of Civil Engineering

Application of the Isolation Layer in Tunnel Crossing the Soft and Hard Rock Junction Subjected to Seismic Waves


Guangyao Cui; Jianfei Ma;


Tunnels crossing the soft and hard rock junction suffer severe damages during strong earthquakes. In this paper, elastic-plastic numerical models considering the modified wave, the boundary condition and the monitoring system are established to investigate the seismic performance of the isolation layer in the soft and hard rock junction of the tunnel. The results show that tunnel safety is related to the proportion of soft and hard rocks, where the larger the proportion of soft rock is, the more vulnerable is the tunnel structure to the seismic waves. The maximum principal stress of secondary linings decreases by 50.23%-89.96%, 51.16%-98.95% and 55.98%-97.39%, respectively, when the dip angle of the soft and hard rock interface is 45°, 60° and 75° after the isolation layer is adopted. The seismic effects of the isolation layer with dip angles of 45°, 60° and 75° are 2.45%-121.67%, 13.19%-66.98% and 4.60%-131.83%, respectively. The application of the isolation layer significantly increases the safety of the tunnel crossing the soft and hard rock junction, except for the structure located at the soft-hard rock interface. It is suggested to adopt both isolation measures and structure reinforcements at the structure intersecting the soft and hard rock interface.


Tunnel engineering, Seismic response, Isolation layer, Seismic waves.