降雨对滑坡形态影响的宏细观分析

Macro-meso analysis of the influence of rainfall on landslide form

进行人工降雨诱发边坡滑坡的模型试验,着重研究不同降雨强度对滑坡形态的影响。基于不同降雨强度下边坡发生滑坡的破坏过程,利用高速动态数据采集仪和孔隙水压力传感器进行孔压量测;利用土体水分传感器监测降雨过程中坡体内部含水率的变化情况,研究含水率和饱和度对滑坡形态的影响;并结合细观组构变化进行水土作用机理分析。研究结果表明:不同降雨强度下坡体发生滑坡的宏观破坏形态、孔压变化规律不同;随着降雨强度的增加,坡体滑坡形态从牵引式向推移式转化;牵引式滑坡形成机理为坡脚发生渗透破坏,坡体失去坡脚支撑作用而分层下滑;推移式滑坡形成机理为坡体上部雨水聚集导致孔压上升、土体强度降低,当下滑力大于抗剪强度时,上部土体挤压下部土体,突然整体滑动。本文研究有助于工程中对降雨诱发滑坡的预防和治理。

A model experiment of landslide induced by artificial rainfall was carried out to study the influence of rain fall intensity on the landslide form. Based on the failure process of landslide under different rainfall intensities,pore water pressure was measured by high-speed dynamic data acquisition instrument and precise pore water pressure sensors. The water content in the slope body was measured by soil moisture sensor to study the influence of water content and saturation on landslide configuration.Combined with the change of micro-structure,the interaction between water and soil was analyzed. The results show that the macroscopic failure modes of slope and the variations of pore water pressure are different under different rainfall intensities. The tractive landslide changes into the plusus landslide with the increase of rainfall intensity. The forming mechanism of tractive landslide into plusus landslide is that the seepage failure at toe of slope causes the layered slide of the slope which has lost the support of its toe.The forming mechanism of plusus landslide is the gathering of rain at the upper slope body causes the increase of pore water pressure and the reduction of soil strength and then the whole sliding occurs suddenly when the sliding force exceeds the shear strength of the soil. This paper is beneficial to prevent and treatment of landslide induced by rainfall.