下伏软弱层黄土边坡变形机制分析及治理对策研究

本文研究了陕北某电厂夹断层破碎带上覆黄土的泥岩、砂岩互层反倾边坡的变形机制,并研究治理对策及其治理效果。通过边坡工程地质条件及变形破坏特征分析,建立FLAC3D地质模型,采用数值模拟方法研究了边坡变形破坏机制,在此基础上提出削方减载、锚筋桩、锚杆及坡面防护的综合治理措施。研究结果表明,边坡的变形受开挖坡形的影响,坡体浅表层特别是断层带及坡顶黄土部位出现大范围拉应力集中,断层带出现向坡外的挤出变形,带动上部黄土的牵引式变形,引起沿黄土和基岩基覆界面的剪切变形,在黄土中出现大量拉裂缝,在一定条件下潜在滑移面逐渐贯通,坡体将产生整体失稳。边坡的治理应通过削方减载改善坡体应力环境,并重点控制断层带及黄土与基岩基覆界面的变形,数值模拟结果表明,治理后边坡稳定性较好,满足设计要求。

DEFORMATION MECHANISM OF LOESS SLOPE WITH WEAK INTERLAYER AND ITS STABILIZATION MEASURES

In recent years,more and more loess slopes are excavated in Northwestern China.The instability of slopes affects the engineering facilities,so it is important to study the deformation mechanism and design reasonable stabilization countermeasures.This paper examines the deformation mechanism of one counter-tilt slope composed of sandstone and mudstone with loess covering and fault zone passing through.Based on analysis of engineering geological conditions and deformation characters,the slope deformation mechanism is studied.Three-dimension geological model is established to analyze the distribution of stress and strain of slope.Flac-3D software is used to simulate the excavation process of the loess slope.The numerical result indicates that large area tension stress distributes in fault and loess at upper slope.The rock mass in counter-tilt fault moves along the fault.,Shearing deformation generates in the lower slope along interface between bedrock and loess and develops upward.The pull-type deformation occurs in loess at the upper slope under this type of stress state.Therefore,the control of the slope deformation should concentrate on improvement of the stress state with unloading and controlling deformation of interface between bedrock and loess.At last,the control measures include offloading,steel pile,anchor and slope protection.