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