Seismic stability analysis of slopes with pre-existing slip surfaces Seismic stability analysis of slopes with pre-existing slip surfaces

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Vol15 No.6: 1331-1341

Title】Seismic stability analysis of slopes with pre-existing slip surfaces

Author】SU Li-jun1,2,3; SUN Chang-ning1,3*; YU Fang-wei1,3; ALI Sarfraz4

Addresses】1 Key Laboratory of Mountain Hazards and Earth Surface Process of Chinese Academy of Sciences, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China; 2 CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China; 3 University of Chinese Academy of Sciences, Beijing 100049, China; 4 School of Advanced Geomechanical Engineering (SAGE) and Research Center of CPEC (RCC), National University of Sciences and Technology (NUST), Pakistan

Corresponding author】SUN Chang-ning

Citation】Su LJ, Sun CN, Yu FW, et al. (2018) Seismic stability analysis of slopes with pre-existing slip surfaces. Journal of Mountain Science 15(6). https://doi.org/10.1007/s11629-017-4759-3

DOI】https://doi.org/10.1007/s11629-017-4759-3

Abstract】In analyzing seismic stability of a slope with upper bound limit analysis method, the slip surface is often assumed as a log-spiral or plane slip surface. However, due to the presence of a weak layer and unfavorable geological structural surface or a bedrock interface with overlying soft strata, the pre-existing slip surface of the slope may be irregular and composed ofa series of planes rather than strictly log-spiral or planeshape. A computational model is developed for analyzing the seismic stability of slopes with pre-existing slip surfaces. This model is based on the upper bound limit analysis method and can consider the effect of anchor bolts. The soil or rock is deemed to follow the Mohr-Coulomb yield criterion. The slope is divided into multiple block elements along the slip surface. According to the displacement compatibility and the associated flow rule, a kinematic velocity field of the slope can be obtained computationally. The proposed model allows not only calculation of the rate of external work owing to the combined effect of self-weight and seismic loading, but also that of the energy dissipation rate caused by the slip surface, interfaces of block elements and anchorage effect of the anchors. Considering a direct relationship between the rate of external work and the energy dissipation rate, the expressions of yield acceleration and permanent displacement of anchored slopes can be derived. Finally, the validity of this proposed model is illustrated by analysis on three typical slopes. The results showed that the proposed model is more easily formulated and does not need to solve complex equations or time consuming iterations compared with previous methods based on the conditions of force equilibrium.

Keywords】Slope stability; Pre-existing slip surface; Seismic loading; Limit analysis; Yield acceleration; Permanent displacement