Initiation mechanism of earthquake-induced large landslides considering structural damage

Rock landslides are generally controlled by a series of discontinuities that relate to faults, folds and shear zones, which provide potential failure boundaries. To study the influences of rock mass damage and discontinuous geological interface on the formation and initiation of landslides under the background of fault and anticline, four large landslides triggered by the Wenchuan Ms8.0 earthquake in the carbonate strata of two wings of Dashuizha anticline are selected as examples to carry out detailed engineering geological investigation, structural plane survey, rock testing and rock quality assessment of GSI. The results show that there are clear differences in structural damage caused by fault and anticline. Gradually, the rock mass quality increases from the axis of anticline to the two wings, only decreases significantly locally, and controls the formation position of landslides. Meanwhile, under the background of structural damage, the structural plane and weak zone of specific rock jointly determine the initiation mechanism, and the types are summarized as "control side sliding type", "control bottom sliding type", "control sliding body type" and "control base type". In addition, the comparison of GSI of seismic and non-seismic landslides reveals that strong earthquake may promote the rapid start of landslides by reducing the rock mass quality, and then accelerate the process of geomorphic erosion in the structural damage area. Finally, it is believed that considering the rock mass damage in complex tectonic environment is very important to assess the location and initiation mechanism of potential large-scale landslides caused by strong earthquakes.