Comparing two methods to estimate lateral force acting on stabilizing piles for a landslide in the Three Gorges Reservoir, China

Abstract

Stabilizing piles are used worldwide to stabilize unstable slopes. However to date, there is little coverage in the scientific literature on the effects of the pore water pressure and the shear strength of the slip zone on the lateral force acting on the piles. This paper presents and compares two methods to estimate the lateral force acting on the stabilizing piles. These are the limit equilibrium method (LEM), and the finite element shear strength reduction method (FE-SRM). For both methods, the COMSOL software was used to model the infiltration of reservoir water and rainfall into the sliding mass. The distribution of lateral force was then simulated by the normal stress distribution on the piles with FE-SRM in PLAXIS 8.2 software. The effect of shear strength of the slip zone on the lateral force and its distribution were also studied. The lower Ercengyan landslide in the Three Gorges Reservoir was used as study area, with four different hydrological scenarios based on the reservoir water level fluctuations and rainfall amounts. The results show that the lateral force with the LEM method is slightly greater than with the FE-SRM method. The lateral force reaches a peak when the level of the reservoir rises to 175m combined with high rainfall amount, and decreases linearly as the effective shear strength of the slip zone increases. The distribution of the lateral force is parabolic, and varies with the shear strength parameters of the slip zone. In conclusion, the LEM and FE-SRM methods can be used to calculate the lateral force acting on the stabilizing piles, and estimate the lateral force distribution. This technique effectively analyzes the behavior of stabilizing piles for landslides. It can be applied in the routine practical design of stabilizing piles in the Three Gorges Reservoir as well as other similar areas.