Dynamic stability of slopes with interbeddings of soft and hard layers under high-frequency microseims

Since the impounding of Three Gorges Reservoir (TGR), the microseismic activity is intensified and the earthquake intensity is increased. The high-frequency microseisms induced by TGR will have some influence on the slopes. The evolution process of failure and dynamic stability are studied based on the shaking table tests and UDEC numerical analysis method. The results are as follows: the natural frequencies decrease with the loading times, while the damping ratios increase. The descending rate of the frequencies increases with the loading times and earthquake amplitude. The PGA magnification factors decrease at different loading stages, showing that the dynamic response becomes weaker. The soft layers tend to be the dominant areas where shear failure occurs in the slopes. The whole model slope eventually presents a segmented failure process,whose upper part of soft and hard layers slides and then the slope slides along the transfixion surface forming with the shear fracture in the upper soft layer, tension fracture of secondary joint in the intermediate hard layer and shear fracture in the lower soft layer. UDEC numerical simulation shows that the permanent displacement increases with the loading times, while the stability coefficient decreases. The research results are of some value to the understanding of the formation mechanism of reservoir landslides and the prevention of disasters.