断层破碎带条件下组合式圆截面抗滑桩加固边坡效果研究

随着我国公路建设不断向山区深入, 在地质构造复杂区公路边坡遇到断层破碎带的情况日渐增多, 亟需开展阻滑能力强的抗滑桩结构加固边坡研究。传统的人工挖孔桩施工模式存在高风险、低效率等缺点, 而组合式圆截面抗滑桩具有施工效率高、安全便捷等特点, 为此, 探究其对含断层破碎带边坡的加固效果具有现实意义。采用自主设计的边坡物理试验系统, 设计了5种不同破碎带厚度与组合式圆截面抗滑桩组合的物理模型, 采用坡顶逐级加载的方式模拟加载, 监测桩身应变、桩顶位移和桩后土压力, 采用高速相机捕捉滑体变形破坏图像, 并使用粒子图像测速(PIV)技术对图像进行处理。研究结果表明: 组合式圆截面抗滑桩通过限制桩后滑体水平位移, 并将滑体限制在前、后排桩间来达到加固边坡的效果; 滑体演化分为变形压密、加速变形和破坏滑移3个阶段; 前、后排桩桩后土压力比值介于1/3~1/2之间; 随断层破碎带厚度增加, 滑体水平滑移速率增大, 组合式圆截面抗滑桩的桩顶位移增大, 桩身最大正弯矩减小。模型试验与数值模拟计算的弯矩及桩顶位移较为吻合, 研究成果可为边坡工程组合式圆截面抗滑桩设计提供一定借鉴与参考。 

Effect of combined anti-slide piles with circular section to reinforce the slope containing the fault crushed zone

With the continuous development of highway construction in mountainous areas in China, an increasing number of highway slopes encounter fault crushed zones in complex geological structures. It is urgent to strengthen slopes with anti-slide pile structures. However, the traditional manual digging pile construction mode has several disadvantages such as high risk and low efficiency. In contrast, the combined anti-slide pile with circular section shows great advantages of high construction efficiency, safety and convenience. Therefore, it is of practical significance to explore its reinforcement effect on slopes with fault crushed zones. In this paper, five physical models of different thicknesses of broken zones and combined anti-slide piles with circular section are designed by using a home-made slope physical test system. The loading is applied on the slope top step by step. Pile strain, pile top position and soil pressure behind the pile are monitored during loading. A high-speed camera was used to capture the images of sliding body deformation and damage, which were post-processsed using PIV technology. Experimental research shows that the combined anti-slide pile with circular section can reinforce the slope by limiting the horizontal displacement of the sliding body behind the pile and confining the sliding body between the front and rear piles. The evolution of the sliding body can be divided into three stages: deformation compaction, accelerated deformation and failure slip. The ratio of the soil pressure behind the piles of the front and rear piles is between 1/3 and 1/2. The position of the maximum positive bending moment will move down after fracturing of the fault crushed zone. The thickness of the fault crushed zone affects the reinforcement effect of the combined section anti-slide pile with circular section. With the increase in the fault crushed zone thickness, the horizontal slip rate of the sliding body increases, the pile top displacement increases, and the maximum positive bending moment decreases. The bending moment and pile top displacement calculated by the model test and numerical simulation are in good agreement. The research results can provide a reference for the design of combined anti-slide piles with circular section in slope engineering.