考虑非均质各向异性效应的阻滑桩加固土坡稳定性分析

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

基于极限分析上限定理与土的抗剪强度折减系数概念,考虑土的强度分布的非均质性与各向异性,建立了土坡的极限平衡状态方程,由此确定土坡的稳定安全系数及其相应的潜在破坏模式。对于在给定的荷载条件下不能满足抗滑稳定性要求的土坡,考虑采用阻滑桩加固方式,根据桩侧有效土压力的合理分布模式确定桩体与滑动面相交的截面上等效抗滑力和抗滑力矩,考虑土的强度非均质性与各向异性的条件,利用极限分析上限定理建立阻滑桩加固土坡的极限平衡状态方程,将桩侧土压力作为目标函数,运用数学规划方法确定极限平衡状态时的临界桩侧有效土压力。通过大量的变动参数对比计算,探讨了土的强度的非均质性与各向异性等因素对阻滑桩桩侧极限抗力及最优加固位置的影响。

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-φ 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.