分层填筑对桩-锚-加筋土组合结构加固边坡试验研究

Effects of layered filling on slope reinforcement with pile-anchor-reinforced soil composite structure

本文以攀枝花机场12#滑坡治理工程为背景,通过模型试验与有限元数值模拟结合分析加筋土分层回填对桩-锚-加筋土组合结构加固边坡的影响,得出以下结论:(1)随着回填高度的增加,水平位移主要向后排桩以前的坡面方向发展,竖向位移主要向后排桩以后的方向发展,在后排桩顶部形成位移拱效应;(2)随着回填高度的增加,后排桩顶的填土与桩体存在较大的刚度差异,使得填土的竖向位移在桩顶受到明显约束,因此在后排桩顶回填时宜增设垫层结构来减弱变形不协调问题;(3)随着回填高度的增加,前、后排桩的受力模式从锚固力控制的外侧受拉逐步转化为水平推力控制的内侧受拉,期间锚索承载力逐步发挥,桩身最大弯矩由桩顶逐渐转移到滑面位置;(4)前两级加筋土工况下前排桩锚索轴力增长较快,后两级加筋土工况后排桩锚索轴力增长较快,这表明高填方情况下后排桩身承受更大的水平荷载;(5)通过强度折减法分析各回填工况下的边坡稳定性,得出随着桩-锚-加筋土组合支护体系的逐步形成,该边坡的稳定性达到了较高的安全系数。

Taking Panzhihua Airport 12 # landslide control project as a case study,the model test and finite element numerical simulation are adopted to analyze the influence of reinforced soil layered backfill on the slope reinforcement with pile-anchor composite structure. The following conclusions are drawn:(1) As the height of backfilling increases,horizontal displacement mainly develops in the slope direction before the back row piles. The vertical displacement mainly develops behind the back row piles. The displacement arch effect is formed at the top of the back row pile.(2) With the increase of backfill height,there is a greater stiffness difference between the backfill and the pile body,which leads to the vertical displacement of the fill berestrained obviously at the top of the pile,so the cushion structure should be added to reduce the deformation incoordination.(3) With the increase of backfill height,the stress mode of the front and back piles is gradually transformed from the lateral tension controlled by the anchor stress to the inner tension controlled by the horizontal thrust,while the bearing capacity of the bolt is gradually exerted,and the maximum bending moment of the pile body is gradually transferred from the top of the pile to the position of the sliding surface.(4) The axial force of the front row pile increases rapidly under the working condition of former two grades of soil reinforced,and the axial force of the anchorage cable increases rapidly under the condition that the post two grade soil reinforced,which indicates that the rear pile body is subjected to a greater horizontal load in the case of high fill.(5) The stability of slope under various backfilling conditions is analyzed by the strength reduction method. With the gradual formation of pile-anchor-reinforced soil combination support system,the slope obtained a high safety factor.