Three-Dimensional Stability Analysis of Slopes Reinforced with Piles Considering the Rotation of Principal Stresses

Accurate evaluation of the lateral force acting on the stabilizing piles is greatly significant for the stability analysis of a slope reinforced with piles. The presence of friction on the pile surface can induce rotation of the principal stress within the soil mass behind the piles, which is always ignored in the previous stability analysis of pile-reinforced slope. In this study, the three-dimensional stability of earth slopes reinforced with stabilizing piles has been evaluated by the analytical upper-bound limit analysis method. A three-dimensional rotational collapse mechanism, which accounts for the end effects of the slope failure, is adopted to attain the theoretical upper bound of the safety factor of the slope. The effect of the principal stress rotation induced by the friction between pile and soil on the lateral force acting on the piles is integrated into the dissipation calculation. Parametric studies are subsequently carried out to explore the influence of the geometrical dimension of the slope, the strength property of the soil, and the location of the stabilizing piles on the safety factor of the slope. The results show that the optimal installed location for the stabilizing pile varies with the parameters concerned. Finally, the proposed approach is strengthened by a real case study, which provides more confidence for using this method in the assessment of three-dimensional stability of a piled slope.