预应力锚索修复含微裂纹抗滑桩模型试验研究

Model test of anti-slide pile with micro-crack repaired by prestressed anchor cables

施加预应力锚索是修复含微裂纹抗滑桩最重要的手段之一。为了探讨施加预应力锚索修复含微裂纹抗滑桩的可行性以及修复过程中抗滑桩变形破坏特征,采用大型物理模型试验对预应力锚索修复含微裂纹抗滑桩进行了研究。试验结果表明,施加预应力锚索修复含微裂纹抗滑桩可提高抗滑桩承载储备能力;滑坡荷载-桩顶位移曲线可分为挤密、线弹性变形与破坏3个阶段;滑坡荷载下桩体在滑面附近位置发生破坏,破坏具有突发性;预应力荷载下抗滑桩在锚索孔位置产生拉破坏,并伴随滑面位置裂纹的扩展;滑坡荷载下桩后土压力呈三角形分布,施加预应力荷载后土压力呈倒梯形分布;锚索预应力的施加降低了弯矩峰值,但最大弯矩位置向锚索孔位置以及滑面附近位置转移,该2处位置是采用预应力锚索修复抗滑桩的薄弱部位。研究成果对于预应力锚索修复含微裂纹抗滑桩技术的推广应用以及抗滑桩修复工程的设计具有指导意义。

Application of prestressed anchor cables is one of the most important methods to repair anti-slide piles with micro-cracks.This paper examines the anti-slide pile with micro-crack repaired by prestressed anchor cables by using of the large physical model test,to discuss the feasibility of anti-slide pile repair and to obtain the characteristics of deformation and failure during the repair engineering.Test results show that(1)application of prestress anchor cables can improve the bearing capacity of piles with micro-cracks;(2)the characteristic curve of pile top displacement under the landslide loading can be divided into three stages,i.e.,the stage of compaction,elastic deformation and failure;(3)failure occurs in the pile near the location of the sliding surface under the landslide loading,and this failure is sudden,and tension failure occurs in the pile at the location of the anchor hole under the anchor cable prestress,meanwhile,cracks extend at the location of the sliding surface.The soil pressure presents triangular distribution under the landslide loading and inverted trapezoidal distribution under the anchor cable prestress,and the earth pressure peak is transferred from the sliding surface to the pile top.Prestress applied to piles lowers the value of the maximum bending moment,but the position of the maximum bending moment transfers to the anchor hole position and the position near the sliding surface,thus the two positions are the weak part of the pile by using of the prestressed anchor cables to repair the pile with micro-crack.The research results are of guiding significance for the popularization and application of anti-slide pile with micro-cracks repaired with prestressed anchor cables and the design of anti-slide pile repairing projects.