Genetic Types of Large-Scale Landslides Induced by Wenchuan Earthquake

The "5·12" Wenchuan earthquake induced thousands of landslides, including hundreds of large-scale ones. The deformation and destroy characteristics of 20 large-scale landslides induced by Wenchuan earthquake found in our in-depth investigation and extensive survey, combined with the tools of shaking table test and numerical simulation, we find that their deformation and destroy model and intrinsic mechanical mechanism Wenchuan earthquake are significantly different from those of landsides induced by routine gravity. On the condition of strong shock, the earthquake-horizontal acceleration on the middle-top of the declivity can exceed 1g, and its earthquake horizontal inertia enormously exceeds the tension strength of the rock mass. Seismic action firstly shaped a deep large fissure which was parallel to the clinohedron on the back of the slope, and then the bottom of the pull-apart rock mass engendered shearing glide, finally, there induced landslide. On the condition of strong shock, the most essential deformation and destroy element of the slope rock mass are tension-cracks and shearing glide, and mainly dominated by tension-cracks. With different slope structures, the bottom shearing glide occurs with different discontinuities. According to the geological environment of the landsliding source region as well as the characteristics of the slope form and lithological association, this paper divides the large-scale landslides induced by Wenchuan earthquake into five genetic types, namely, tension-cracking and consequent sliding, tension-cracking and bedding sliding, tension-cracking and horizontal sliding, tension-cracking and scattering sliding and tension-cracking and shearing sliding.