阻滑桩加固土坡稳定性分析与桩基的简化设计

STABILITY ANALYSIS OF SLOPES WITH STABILIZING PILES AND THEIR SIMPLIFIED DESIGN

基于极限分析上限定理与土的抗剪强度折减系数概念,建立了土坡稳定的极限平衡状态方程,以此确定土坡稳定的安全系数及相应的潜在破坏模式。通过针对典型算例所进行的对比计算与分析,验证了该方法的可靠性。进而针对潜在失稳土坡,建立了阻滑桩加固土坡的极限平衡状态方程,将桩侧有效土压力作为目标函数,运用数学规划方法确定了极限平衡状态时的临界桩侧有效土压力,以此进行土坡预加固中阻滑桩的简化设计。最后,根据最大、最小值原则,探讨了阻滑桩的最优桩位问题,并通过变动参数比较计算对影响加固力的有关因素进行了分析。

Based on the kinematics approach of limit analysis and the concept of shear strength reduction, the equation for expressing the limit-equilibrium state is formulated and is employed to determine the factor of safety and its corresponding critical failure mechanism for a given slope. Through numerical analysis of typical examples and comparisons with the results computed by using both limit equilibrium method and finite element method, the reasonability and applicability of the proposed procedure are verified. Then, for the slopes whose factors of safety cannot fulfill the requirement of overall stability for the given loading condition, the stabilizing pile is considered for reinforcement of the slope. The upper-bound theorem of limit analysis is employed once again for establishing the limit-equilibrium equations of the slope reinforced by stabilizing pile in which the mobilized strength parameters are given by the actual strength parameters with a reduction by the desirable overall factor of safety. The lateral effective earth pressure acting on the pile can be chosen as the objective function; the mathematical optimization technique is utilized to define the critical state. The dimensionless critical overall lateral effective earth pressure is used in the structural simplified design of pile. Finally, the principle of maximum and minimum values is employed to optimize the most rational location of piles within slope. Based on comparative studies for different combinations of related parameters, the effects of some factors on the stabilizing forces which are required to increase the factor of safety to a desired value are examined systematically.