Abstract: In order to get the seismic permanent displacement of clay slope reinforced with cantilever stabilizing piles effectively, based on the upper bound theorem of limit analysis and circular failure mode of soil slope, factor of safety and the corresponding yield acceleration of slope with stabilizing piles under the earthquake can be derived through calculating the rate of work done by external loads and the energy dissipation rate. Then, combined with the Newmark’s sliding block method, the expression for the seismic permanent displacement related to design safety factor can be deducted by the double integrals of the rotational acceleration of slope. The paper takes a clay slope reinforced with cantilever stabilizing piles under the 5.12 Wenchuan Earthquake for example, the validity of the proposed method is verified by comparison with Ambraseys’s method. In Addition, the permanent displacement time history of the reinforced slope is given, and the relationship between the permanent displacement and factor of safety of the slope is also shown. The laws that the permanent displacement affected by the cohesion and internal friction angle of soil under different safety conditions are obtained. The research results show that the permanent displacement exponentially decreases with design safety factor of the slope increasing. In the case of lower design safety factor, the permanent displacement is more sensitive to soil shear strength parameters. However, the sensitivity is gradually reduced with the increase of the design safety factor.

Key words: clay slope, cantilever stabilizing pile, design safety factor, yield acceleration, permanent displacement