抗滑桩加固边坡三维数值分析中的几个问题

就当前抗滑桩加固边坡三维数值分析中存在的几个问题，开展了有针对性的研究。利用考虑桩-土-边坡相互作用的强度折减有限元程序，结合典型边坡算例，深入探讨了抗滑桩-边坡体系的计算模型尺度、设桩位置、桩间距（S）与桩径（D）之比（S/D）、桩长与桩底接触模式等因素对边坡稳定安全系数及临界滑动面的影响，以及不同桩头约束下抗滑桩内力分布等。研究表明，单桩取半、单桩、双桩取半、双桩、单桩加双桩取半5种尺度计算模型所得边坡的安全系数并无差异，模型尺度为0.5S时的计算工作量最小；抗滑桩加固于边坡中部可获得最大的安全系数，坡顶或坡脚处安全系数略高于无桩状态，总体上其安全系数与设桩位置的变化曲线近似为一抛物曲线；边坡安全系数随S/D的增加而减小，其最优的比值宜为S/D =2～6，此时桩间存在土拱效应；均质土坡中抗滑桩锚固深度宜为2/5桩长；其结果可为抗滑桩工程设计及规范修订提供参考。

Several issues in three-dimensional numerical analysis of slopes reinforced with anti-slide piles

Several key issues in three-dimensional numerical analysis of slopes reinforced with anti-slide piles are systematically studied.A large finite element program considering the interaction of pile-soil-slope is used to achieve the factor of safety(FOS) and the critical slip surface(CSS) for the slopes stabilized by a row of piles,some key factors such as computational model scale,pile location,ratio of pile spacing to pile diameter,pile length and contact mode at the pile bottom are adequately discussed combined with a typical slope example.In addition,bending moments,shear force,horizontal displacement and lateral earth pressure for the stabilizing piles under four pile top constraints are also analyzed in detail.Some important conclusions are drawn according to the research results to guide the engineering practice and amend the design code for stabilizing piles,which include:(1) The FOS for a slope with reinforcing piles is the same under five computation model scales such as half pile,single pile,double of half piles,double piles,single pile and double of half piles.However,the computational cost under half pile condition is the least one.(2) The maximum FOS can be obtained when the piles are inserted in the middle of the slope,rather than the top or the toe of the slope.The relation between the FOS and pile location in a slope shows a parabolic curve.(3) The FOS for a slope with reinforcing piles will decrease with the increasing the ratio of pile spacing to pile diameter,the optimal ratio is S/D =2-6,because soil arching is formed between the piles.(4) The optimum stabilizing depth for the pile in homogeneous soils can be chosen to be 2/5 pile length.