澜沧江昌都段滑坡发育特征及形成机制

Development and formation mechanism of landslides along Changdu section of Lancang River

中国的山区和高原发育的滑坡地质灾害最严重,青藏高原东部横断山区的大江大河沿岸发育一系列严重和频繁的地质灾害。基于前期InSAR遥感解译的工作,通过现场的野外详细调查,最终确定了澜沧江昌都段的75处滑坡地质灾害,详细分析了滑坡的发育特征和主要影响因素,总结了砂泥岩软弱地层区滑坡、断裂控制型滑坡、堆积层滑坡共6类典型滑坡的形成机制。结果表明:(1)澜沧江干流岸坡的滑坡中,堆积层的土质蠕滑滑坡最发育,河流切坡是临江土质滑坡的主要触发因素。临江高位滑坡往往表现出高位但不远程的特征;(2)岩质滑坡中最发育的两类斜坡结构分别为反向斜坡和顺向斜坡,这与砂泥岩软弱岩体中发育的层理及垂直于层理的主控节理直接相关;(3)85%以上的滑坡发育在软-较软沉积岩岩组中,表明岩石强度一定程度上影响了滑坡的发育。区内斜坡表层的强风化带及古(老)滑坡的堆积体为堆积层滑坡提供物质基础,该类滑坡多存在蠕滑和多级滑动的特征;(4)卡贡-盐井活动断裂对滑坡灾害空间分布具有明显的控制作用,表现在断裂带控制滑坡边界和破碎带直接成为滑体。研究结果可为铁路修建过程的边坡灾害管控提供参考和支撑。

The most serious geo-hazards always occur in mountainous areas and plateaus in China,and a series of serious geo-hazards have occurred along the major rivers in eastern Tibet Plateau.Based on the previous research of InSAR remote sensing interpretation,through detailed field investigation,75 landslides were determined along the Changdu section of Lancang River.Based on the analysis of the development characteristics and main influencing factors of landslides in detail,the formation mechanism of 6 types of typical landslides was summarized.The result shows that among the landslides along the Lancang River,the creep landslide in the accumulation layer is the most developed,and the river-cut slope caused by the rise and fall of the water level is the main influencing factor of the soil landslides along the river.High-location landslides near the river often slip directly into the valley,showing the high location but not remote characteristics.The two most developed types of slope structures in rock landslides are reverse and dip slopes,which are directly related to the bedding developed in the weak rock mass of sand and mudstone and the main joints perpendicular to the bedding.More than 85% landslides occur in the soft-little soft sedimentary rock association,indicating that the rock strength affects the development of landslides to a certain extent.The strong weathering zone on the surface of the slope and the accumulation body of the ancient landslide provide the material foundation for the landslides in accumulation layer,and these landslides are mostly characterized by creep sliding and multi-stage sliding.The Kagong-Yanjing active fault controls the spatial distribution of landslides.The faults control the landslide boundary and the fracture zone directly becomes the slide body.The results can provide reference and support for slope hazard management during the railway construction.