Study On Dynamic Response Of Talus Slope Under Strong Earthquake

China's geological structure is complex and occurs frequently. Caused by geological disasters has the characteristics of wide distribution and great hazards. Among them, the losses caused by the earthquake landslide is the most serious. Therefore, it is significant to study the dynamic response of slope under earthquake action.The talus slope in front of dam on the left bank is located in ahead of the water diversion system of Zipingpu Water Conservancy Project. After the “5.12” Wenchuan earthquake, the talus slope arises significant deformation. Its instability will cause an important impact on the dam and downstream people's lives and property. This paper is based on the engineering geological condition of the talus slope, combined with in situ monitoring, shaking table test and numerical simulation. Comparing between them, the main results we obtained are as follows:(1) Analysis the deformation characteristics of the talus slope before and after the earthquake by in situ monitoring. Before the earthquake, the surface displacement of the talus slope is small; the displacement vector azimuth angle is not obvious; the base cover interface does not have the dislocation; and the talus slope is in the steady state. After the earthquake, the leading edge of Dengzhanping occurs three small collapses; the road appears several cracks. The displacement of slope surface is increased by 77~219mm. The internal has obvious dislocation, and the based of the interfacial dislocation changes 31~64mm. The earthquake causes obvious convergence in the deformation direction of the talus slope. The surface displacement vector azimuth mean is 134°, and vertical intersection with the Wenchuan seismic fault zone. After experiencing several aftershocks, rainfall and reservoir water rise and fall, the deformation of the talus slope has not been further developed.(2) Shaking table test was used to study the deformation and failure characteristics, dynamic response regularity and mechanism of the talus slope under earthquake action. The deformation and failure process of the talus slope is divided into four stages: the top tension crack formation- crack extension down through the cracks- crack coalescence and leading edge shear exit formation- instability failure. The talus slope has horizontal, elevation and topographic amplification effects under earthquake action. The PGA shows obvious nonlinear variation under different amplitude seismic wave. With the increase of sine wave frequency, the PGA of each measurement point is increased gradually.(3) Analysis the dynamic response of plastic zone, strain, displacement and acceleration by numerical simulation. The displacement of the talus slope changes slightly, the force is in balance state and the stability is good under gravity conditions. Under earthquake, the displacement and strain of the talus slope are concentrative, the shear and tension zone of base cover interface are linked as well. These lead the talus slope to large deformation. The talus slope has horizontal, elevation and topographic amplification effects as well. The PGA in slope surface decreases with the increase of amplitude, however, the PGA near the base cover interface increases with the increase of the amplitude. As the frequency increases, the PGA of each measurement point decreases gradually. With the increase of duration, the PGA has no change.(4) There are horizontal, vertical and slope surface amplification effects among in situ monitoring, shaking table test and numerical simulation. The deformation and failure characteristics of these three are consistent basically. The dynamic response regularity of different elevation, amplitude, frequency and seismic wave type between shaking table test and numerical simulation are consistent basically.