PHYSICAL SIMULATION TEST OF INITIATION MECHANISM FOR XINMOCUN LANDSLIDE IN MAOXIAN, SICHUAN

In 2017, the initiation of Xinmocun landslide in Maoxian, Sichuan had obvious "locking section" effect. On the basis of field investigation, we adopt high strength brittle material to make slope model, and used it to carry out physical simulation test for reproducing the process of landslide deformation and failure. We analyze the initiation mechanism of Xinmocun landside under the control of the anti-dip joint and the potential slip fracture surface. We combined the deformation and failure characteristics of the rock mass of the "locking section", and the deformation monitoring data and acoustic emission signals. We found some precursors of landslide. The experiment showed the follows: Due to the push of the upper slide, the rock mass of the "locking section" in the front of the sliding source area expanded and sheared along the anti-dip joints, which formed a bulging fracture on the slope surface and a downslope tension crack surface in the interior of the slope. Next the two groups of fractures were combined to form a stepped failure surface, which formed the boundary condition of rock mass failure in the "locking section". Under the pushing of the upper slide, the middle part of the slope formed the ejection block with high speed. Within the meantime, the lower dumping block toppled over the outside. Subsequently the landslide failed. Therefore, we conclude that the bulging cracks that were formed along the anti-dip joints can be regarded as the macroscopic precursors of this kind of landslides. At the same time, in the yield stage of the "locking section", the displacement ratio between the slope surface and the top increases rapidly and then flattens out with time, representing the gradual penetration of the slide surface. Hence, the ratio tends to be stable with time, which can be used as a precursor of the landslide. The research conclusions have theoretical and practical significance for warning of instability of bedding slopes with anti-dipping joints.