恩施沙子坝滑坡破坏特征与形成机制

Failure Characteristics and Formation Mechanism of the Shaziba Landslide in Enshi

恩施沙子坝滑坡发生于2020年7月,是地质灾害成功预警典型案例之一。在野外地质调查基础上,采用工程地质分析结合三维数值模拟方法,探究沙子坝滑坡破坏特征与形成机制。结果表明,沙子坝滑坡是一个灾害链式滑坡,其3个分区具有不同的形成机制与变形破坏特征;连续强降雨是导致滑坡失稳变形的触发因素。一区变形体垮塌形成堆积体堵塞西侧冲沟,导致区域性地下水位升高,是二区发生整体滑动的主要原因;二区滑动后形成滑坡凹槽,给予一区、三区良好的临空条件,引导一区、三区产生变形破坏。二区滑动时间大约为180 s,破坏模式表现为推移+牵引式,其中部滑体主要起到阻滑作用,阻滑失效后滑坡整体破坏,致使滑体堆积于清江形成堰塞湖。研究成果对未来此类滑坡灾害防治与预测具有重要的参考意义。

The Shaziba landslide in Enshi occurred in July 2020,which is one of the typical cases of successful early warning of geological disasters.Based on the field geological investigation,the failure characteristics and formation mechanism of Shaziba landslide are explored by engineering geological analysis combined with three-dimensional numerical simulation.The results show that the Shaziba landslide is a disaster chain landslide with different formation mechanisms and damage characteristics in three zones,continuous heavy rainfall is the triggering factor leading to the instability and deformation of landslide.The collapse of the deformed body in the landslide area forms a mound blocking the western alluvium,leading to a regional rise in the water groundwater level,which is the main reason for the overall sliding in Zone 2.The sliding of the second zone formed a landslide notch,which gave good proximity to the first and third zones,leading to deformation and damage in the first and third zones;the sliding time of the second zone was about 180 s,and the damage mode is thrust+traction type,with the central slide mainly playing a role in blocking the sliding,and after the failure of the sliding mass,the overall landslide is destroyed,causing the sliding mass to accumulate in the Qinjiang River,and forming a barrier lake.The research results have important reference significance for the prevention and prediction of such landslide disasters in the future.