抗滑桩前预留岩体破坏模式及稳定性分析

Study on failure mode and stability of reserved rock in front of anti-slide piles

为了探究大开挖条件下桩前预留岩体的稳定性,首先基于相似理论开展不同宽度预留岩体的变形及破坏模式试验研究;然后基于极限平衡理论得到不同破坏模式下预留岩体稳定性计算公式;最后以湖南省某滑坡治理桩前大开挖为例,分析不同破坏模式下预留岩体的稳定性变化特征。结果表明:随着桩前预留岩体宽度的增加,其变形总体呈临空面外凸—少量裂缝—桩前岩体顶面隆起的发展趋势;宽度较大的预留岩体易发生上滑移破坏,宽度较小的预留岩体则易发生下滑移破坏;下滑移破坏中,稳定系数随着预留岩体宽度的增大按开口向上的二次函数形式增加。

In order to study stability of rock mass reserved in front of anti-slide piles under large excavation condition,deformation and failure modes of reserved rock mass at different widths were tested and analyzed based on similarity theory.Secondly,formulas for stability calculation of rock mass under different failure modes were deduced according to limit equilibrium theory.Finally,with landslide in Hunan province as research object,stability variance features of the mass under each failure mode was analyzed.The results show that along with increase of width,deformation trend of reserved rock is always in the form of deformation of the excavation surface-a few cracks-local uplift deformation in front of piles.The rock mass with larger width is prone to up-slide failure,while that with smaller width is prone to down-slide one.As width increases,stability coefficient increases in form of a quadratic function with the opening upward under down-slide failure.