Seismic response and damage mechanism of tunnel lining in sensitive environment of soft rock stratum

In order to investigate the dynamic response characteristics and damage mechanism of the tunnel lining at the tunnel portal in the bridge–tunnel overlapping section in soft rock strata, a physical model with the scale ratio of 1:50 was made based on the similarity theory for shaking table tests. The acceleration and strain results of the tunnel lining under EL Centro seismic waves with different acceleration peak values were studied. Test results show that most of the acceleration values have significant amplification effects compared to input seismic waves, which increased significantly with greater peak values and elevations. Tensile deformations appear along the longitudinal and the circumferential directions of the tunnel lining. The tunnel spandrel and tunnel vault are the maximum deformation parts, respectively, at the standard section and the enlarged section of the tunnel lining. Therefore, it is suggested that the longitudinal anti-tensile design of the tunnel lining at the tunnel portal in such sensitive environments should be strengthened. And the anti-seismic design standard and durability requirement of the standard section of the tunnel lining adjacent to the enlarged section should be improved, so as to meet the requirements for stress deformation and overall stability when subjected to severe earthquakes.