锚索抗滑桩加固堆积型滑坡的受力特性模型试验与数值模拟研究

Model test and numerical simulation study on the mechanical characteristics of the anchored slide-resistant pile for stabilizing the colluvial landslide

为研究锚索抗滑桩加固堆积型滑坡的受力特性及其联合抗滑机制,开展了分级推力荷载作用下锚索抗滑桩加固滑坡的室内物理模型试验,分析了模型滑坡从加载到破坏过程中桩顶位移、桩身前后土压力、桩身弯矩、锚索轴力和滑体深部水平位移的变化规律。并采用数值模拟进行对比分析,两者所得结果吻合较好。结果表明:(1)桩顶位移、桩身弯矩及锚索轴力随推力荷载的变化曲线均呈现明显的三阶段特征,对应的桩-锚荷载分担比呈先增大、后减小和最后趋于稳定的规律。(2)桩前滑体抗力呈抛物线型分布,且抗力值较小;桩后滑体推力呈上大下小的抛物线型分布,合力作用点约位于滑面以上0.5h1处(h1为受荷段长度)。(3)桩身最大弯矩点始终位于滑面以下2 cm处,表明桩前滑床并未发生破坏。(4)由桩身实测弯矩计算得到的桩身荷载分布表明,桩体抗力主要由桩前滑面以下滑床提供,且呈倒三角形分布。(5)锚索的设置能够有效限制桩身变形,同时在工程中更应该注意锚索失效问题。该研究成果可为堆积型滑坡治理中锚索抗滑桩的合理设计提供试验基础。

In order to study the mechanical characteristics and the combined anti-slide mechanism of anchored slide-resistant pile for stabilizing the colluvial landslide, an indoor physical model test of a landslide reinforced by anchored slide-resistant pile under multi-stage loading was carried out. The variation curves of displacement of the pile top, soil pressure at the fore and rear of the pile, bending moment of the pile, axial force of anchor cable, deep horizontal displacement of sliding mass, and the characteristics of deformation and failure of the landslide are analyzed. Moreover, numerical simulation is adopted to compare with the model test and the results conform to each other. The results show that: 1) The horizontal displacement of the pile top, the bending moment of the pile and the axial force of anchor cable all show obvious three-stage characteristics under the variation of thrust load, and the load sharing ratio of the pile over the cable increases at first, then decreases, and finally tends to be stable. 2) The sliding mass resistance force at the fore of the pile is parabolic, and the value of the resistance force is small. The sliding mass thrust load at the rear of the pile is parabolic, and the resultant force point is 0.5 h1 above the sliding surface(h1 is the length of the loaded segment). 3) The maximum bending moment point of the piles is always 2 cm below the sliding surface, indicating that the sliding bed at the fore of the pile has not been damaged. 4) The load distribution of the piles calculated through the measured bending moment of the piles indicates that the resistance force of the piles is mainly provided by the sliding bed below the sliding surface at the fore of the pile,and the resistance force is triangular. 5) The setting of the anchor cable can effectively limit the pile deformation. Meanwhile, the anchor cable failure problem should be paid more attention to in engineering practice. The research results can provide experimental basis for the rational design of anchored slide-resistant pile in the treatment of colluvial landslide.