降雨条件下麻池村1号阶跃型滑坡动态变形特征及成因机理

Dynamic Deformation Characteristics and Mechanism of Machi No.1 Stepped Landslide Under Rainfall Conditions

麻池村1号滑坡是十堰市重点专业监测滑坡,至今仍处于蠕动变形阶段。基于现场工程地质调查和勘查,在分析该滑坡动态变形特征、挖掘其位移监测数据与降雨响应关系的基础上,研究该滑坡在降雨作用下的变形机理,进而评价其稳定性现状并预测其发展趋势。结果表明,麻池村1号滑坡展现出周期性演化规律,在降雨因素的驱动下,位移曲线呈现出典型的阶跃特征;滑坡位移阶跃期相对于集中降雨期存在时间滞后性,基于皮尔逊相关性分析法求得滑坡日位移响应降雨的滞后期为10 d,其中阶跃变形前第2天的降雨量对滑坡影响最为显著;降雨入渗导致滑坡岩土体抗剪强度降低、软弱带内摩擦角和黏聚力大幅降低、滑体下滑力增大,进而导致滑坡稳定性迅速降低而加速变形破坏。目前麻池村1号滑坡变形趋势逐年增大,空间分期配套裂缝体系基本形成,在强降雨等不利条件下产生滑动的可能性较大,必须进一步加强监测预警工作。

Machi No.1 landslide is a key professional monitoring landslide in Shiyan City,which is still in the creeping deformation stage.Based on the analysis of the dynamic deformation characteristics of the landslide and the relationship between the displacement monitoring data and the rainfall response,the deformation mechanism of the landslide under the action of rainfall is studied by means of engineering geological investigation and exploration,and then its stability status is evaluated and its development trend is predicted.The results show that Machi No.1 landslide exhibits a cyclical evolution pattern,and the deformation curve is driven by rainfall factors,showing a typical step characteristic.There is a time lag in the landslide displacement step period relative to the concentrated rainfall period.Based on the Pearson correlation analysis method,the lag period of the daily displacement response rainfall of the landslide is 10 days,and the rainfall on the second day before the step deformation has the most significant effect on the landslide.The rainfall infiltration leads to the decrease of shear strength of landslide rock and soil.The friction angle and cohesion in the weak zone are greatly reduced,and the sliding force of the sliding body is increased,which leads to the rapid decrease of landslide stability and the acceleration of deformation and failure.At present,the deformation trend of Machi No.1 landslide is increasing year by year,and the spatially phased supporting fracture system has basically formed.Therefore,it is more likely to slide under adverse conditions such as heavy rainfall,and monitoring and early warning work must be further strengthened.