大型平缓堆积层滑坡形成机理研究

岑巩县大榕滑坡发生于2012年6月29日, 属于大型平缓堆积层滑坡。其主体堆积区斜坡坡度8～20, 主滑区基覆界面倾角4～11; 下伏基岩中存在强风化层; 2009年以来, 有持续人工弃土堆积于左侧汇水区。结合滑坡特征及三维数值分析可见, 大榕滑坡是由持续人工弃土堆积和强降雨共同诱发产生, 弃土堆积区首先局部失稳, 导致坡脚破坏而逐步引发滑坡整体失稳; 滑面位于下伏强风化层中。结合典型案例, 总结了大型平缓堆积层滑坡结构特征, 强降雨是必要诱发因素; 失稳时, 局部往往带动下伏基岩失稳。

MECHANISM OFLARGE-SCALE GENTLE INCLINED ACCUMULATION LANDSLIDES

Darong landslide in Cengong county happened on June 29, 2012. It is a large-scale gentle inclined landslide accumulation deposits. The gradient of slope in the main accumulation area is between 8to 20.The dip angle of the interface between the bedrock and accumulation layer in main sliding area is between 4to 11.Strongly weathered layer distributes in the underlying bedrock. Since 2009, artificial soil has been continuously piled up on the catchment area on the left of accumulation area. Based on characteristics and 3D numerical simulation analysis, the artificial soil and heavy rainfall are the common inducing factor of Darong landslide. They firstly locally made the artificial soil area unstable. Its foot is therefore damaged, and gradually leads to the slope failure. The sliding surface is in the strongly weathered layer. In combination with other typical cases, the structure characteristics of the large gentle inclined accumulation landslide are summarized. Heavy rainfall is the necessary inducing factor of this landslide. When these landslides occur, the local underlying bedrock is often driven.