成对分布的黄土滑坡形成机理研究

Study on Formation Mechanism of Paired Loess Landslides

银百高速罗圈段冉家沟内的滑坡具有成对分布的特点,且各对滑坡之间具有十分相似的变形破坏特征。通过分析现场的地质勘察资料,结合工程地质学和地貌学基本理论知识,对成对分布的黄土滑坡形成机理进行研究。冉家沟内滑坡形成的基本条件为复杂的地形地貌、特殊的地层结构和地质构造。滑坡发生的主要诱发因素是降雨,流水先对冉家沟凹岸侵蚀,导致该侧坡体失去支撑发生牵引滑动,巨大的滑体涌入沟道将其堵塞,沟内流水汇集形成一定规模的堰塞湖,湖水汇集到一定程度后,水流改道侵蚀对岸坡体,再引发对岸坡体失稳滑动,从而形成了目前成对分布的滑坡。成对分布的滑坡具体形成过程可以分为6个阶段,依次是流水对凹岸的侵蚀阶段、凹岸坡体失稳滑动阶段、流水对凸岸的侵蚀阶段、凸岸坡体失稳滑动阶段、滑坡前缘受水冲刷阶段以及滑坡次级滑面形成阶段。

In the geological mapping process of Luoquan section of Yinbai expressway,it is found that the landslides in Ranjiagou are distributed in pairs,and each landslide has very similar deformation and failure characteristics.Based on the field geological survey data,combined with the basic theoretical knowledge of the engineering geology and the geomorphology,the formation mechanism of paired loess landslides is studied.The basic conditions for the formation of landslides in Ranjiagou are complex topography,special stratum structure and geological structure.The main inducing factor of landslides is rainfall.The formation of the paired distribution landslide is that the water erodes the concave bank of the Ranjiagou first,causing the side slope to lose its support and lead to the traction sliding.The huge sliding mass flows into the gully and blocks it.The water in the gully gathers to form a barrier lake of a certain scale.After the lake water gathers to a certain extent,the water changes the channel and erodes the opposite bank slope,and then causes instability sliding of the opposite bank slope,thus forming the current paired distribution landslide.The formation process of the paired landslides can be divided into six stages,which are the erosion stage of the water on the concave bank,the unstable sliding stage of the concave bank slope,the erosion stage of the water on the convex bank,the unstable sliding stage of the convex bank slope,the water erosion stage of the landslide front and the formation stage of landslide secondary sliding surface.