Multiple earthquake-induced progressive failure of bedding slopes with a saturated weak layer: Shaking table model tests

The Longmenshan (LMS) orogenic belt located in the south-eastern Tibetan Plateau has suffered from frequent earthquakes. Despite the fact that multiple earthquakes can accelerate the catastrophic failure of deep-seated bedding landslides by causing rock mass damage accumulation, the seismic deformation evolution characteristics during the progressive failure have received limited attention. This study employs a physical model of deep-seated bedding landslides with a saturated weak layer as a slope prototype to conduct model tests that simulate the progressive failure induced by repeated earthquakes. Embedded sensors and digital image correlation (DIC) technology were used to monitor the seismic response and deformation evolution of the physical model. During the test, sensors embedded in the saturated weak layer recorded the excess pore water pressure (EPWP). The test results revealed that the EPWP responses are highly related to the input parameters of seismic waves and the seismic damage state of the weak layer. In addition, a deformation coefficient (Dc) was proposed to identify the deformation stages consisting of the release of steep tensile failure surface and the shear failure evolution from stable to accelerated deformation. Finally, the test results indicated that historical seismic damage accumulation will make an important contribution to later earthquake-induced coseismic instability, which provide new insight into the initiation of large landslides triggered by low magnitude earthquakes.