Stability analysis of pile-stabilized slopes considering both nonhomogeneity and anisotropy of soil strength using upper bound method of limit analysis

Based on the upper bound technique of limit plasticity and the shear strength reduction concept, the equation for expressing the critical limit equilibrium state is formulated and is employed to define the safety factor and its corresponding critical failure mechanism for a given anisotropic and nonhomogeneous slope in c-phi soils. Through numerical analyses for typical examples, the solutions computed by the proposed approach are compared with the results available given by limit equilibrium methods and other analytical methods to verify the reasonability of the method. For the slopes of which the safety factor cannot fulfill the requirement of overall stability for the given loading condition, the stabilizing pile is considered for reinforcement of the anisotropic and nonhomogeneous slopes. As the key issue in this circumstance, the equivalent force and moment against sliding induced at the cross-section which intersects the potential slip surface are determined on the basis of the rational distribution mode of net lateral effective earth pressure acting on the stabilizing pile. Then the upper bound theorem of limit analysis is employed again for establishing the limit equilibrium equation of the slopes reinforced by stabilizing piles in which the mobilized strength parameters are given by the actual strength parameters with a reduction by the desirable overall safety factor. The net lateral effective earth pressure acting on the pile can be chosen as the objective function; mathematical programming method is utilized to define the critical state. The critical net overall lateral earth pressure acting on the pile will be used in the structural design of pile. Numerical computations are made to examine the optimum location of pile placement.