抗滑桩加固边坡稳定性3维极限上限拓展分析

抗滑桩作为常用的边坡加固手段，被广泛应用于工程实践中，其影响下的边坡稳定性分析，具有较高的理论和实践价值。采用极限分析上限法，通过引进参数拓展了边坡3维计算模型，建立了内外功率平衡的边坡安全系数计算框架，并通过优化计算得到一定参数条件下边坡的安全系数上限解和最危险破坏机构形状。在此基础上，分析了抗滑桩加固后边坡破坏模式和稳定性受抗滑桩位置、桩距、坡角、机构限宽等参数的影响规律，并讨论了不同参数条件下破坏面形状的变化规律和边坡稳定性变化的内在机理。结果表明：最安全抗滑桩位置不受机构限宽影响，位于坡面中点与坡顶间的某一位置；当机构限宽较小且抗滑桩位置靠近坡趾时，边坡破坏面通过坡面。抗滑桩位置距离坡趾越远，破坏面越靠近坡面且曲率越大。当桩距较小时，边坡倾向于在抗滑桩位置上方发生次级滑动；边坡整体安全系数随桩距的增大而降低。随着机构限宽的增大，边坡安全系数逐渐降低，并逐渐接近2维破坏机构的安全系数。边坡破坏机构随桩距和机构限宽的增大而增厚。当坡角较小时，边坡破坏面通过坡趾下方。本文方法不仅对边坡破坏机构类型的拓展具有理论意义，而且实现了计算结果的进一步优化。

Extended 3D Stability Analysis of a Slope Reinforced with Piles Using Upper-bound Limit Analysis Method

The technique of anti-slide pile is widely applied in practical engineering as a common measure of slope reinforcement. The slope stability analysis considering its effects is of high theoretical and practical significance. Based on the upper-bound limit analysis method, 3D rotational failure mechanisms are extended by introducing new geometric parameters. The calculation framework of safety factor is established considering the equation of internal dissipation and external work rate. The minimum upper-bound solution of safety factor and the most dangerous failure mechanism are calculated through optimization procedure. Parametric studies were carried out to investigate the effects of pile location, pile spacing, slope angle, slope width on the geometry of failure mechanism and the stability of a slope reinforced with piles. The geometry of failure mechanisms is also discussed. The results demonstrate that the most effective location of the anti-slide piles is between the middle and top of the slope, which is not influenced by the slope width. With a relatively smaller slope width and a pile location close to the slope toe, the critical failure surface passes through the slope face. The farther the pile location is away from the slope toe, the closer the failure surface is to the slope face and the greater its curvature. For slopes with small pile spacing, a secondary slope failure tends to occur above the pile location. Furthermore, the safety factor of slope decreases with the increase of pile spacing. The greater the slope width is, the lower the safety factor is and the closer it is to that of a 2D slope. The failure partbecomes thicker as the pile space and the slope width turns larger. While the slope angle is small, the critical failure surface passes below the slope toe and through the slope base. Obviously the extension of failure mechanism leads to additional optimization of the results.