川藏交通廊道怒江段斜坡地质灾害发育特征及主控因素分析

Development characteristics and main controlling factors of the slope geohazards in Nujiang River section of Sichuan-Xizang traffic corridor

青藏高原东南三江流域地质环境脆弱,地质灾害频发。为了有效防控川藏交通廊道怒江段(洛隆―八宿)的地质灾害风险,采用遥感解译、现场调查、GIS空间分析、确定性系数(certainty factor,CF)分析以及敏感性指数(E)分析等方法,在研究区内共识别出斜坡地质灾害(滑坡、崩塌、变形体)992处,分析了灾害的数量、规模和破坏模式等发育特征,揭示了灾害的易发区间和主控因素。研究表明:高程[2672,4500)m,坡度[20,35)°,坡向E、SE、S、SW、W是灾害易发的地形地貌区间;砂砾岩、泥页岩、灰岩岩组、砂板岩夹火山岩岩组、碳酸盐岩岩组、砂板岩夹煤层岩组、大理岩、灰岩夹片岩岩组、片岩、硅质岩和砂板岩岩组是灾害易发的地层岩组;距断裂和距水系距离小于1 km均为灾害易发范围。其中,高程[2672,3000)m、坡度[25,35)°、坡向SW、碳酸盐岩岩组和砂板岩夹煤层岩组是灾害最易发生的因子范围。选取的6个影响因子对斜坡地质灾害的影响大小依次为:高程、岩组、坡度、距水系距离、距断裂距离和坡向,其中前5个因子是灾害的主控因素。本文研究成果可以为川藏交通廊道怒江段的防灾减灾提供科学依据。

The Three-rivers basin of southeast Tibetan Plateau is of fragile geo-environment,and geohazards occurred frequently in this area.Therefore,multifarious methods such as remote sensing interpretation,field investigation,GIS spatial analysis,certainty factor(CF)analysis and sensitivity index(E)analysis were used to effectively prevent and control the geohazards risk in the Nujiang River section(Luolong-Basu)of the Sichuan-Xizang traffic corridor.There were 992 slope geohazards(landslides,rockfalls,deformed masses)recognized in the study area,the development characteristics of the hazards,such as quantity,scale and failure mode,were analyzed,and the prone zones and main controlling factors of hazards were revealed by using these methods.The researches showed that,elevation of[2672,4500)m,slope angle of[20,35)°,and slope aspect at E,SE,S,SW,W were the topographic and geomorphic region prone to hazards.Sandy conglomerate,mudstone and limestone rock group,sandstone and slate intercalated with volcanic rock group,carbonate rock group,sandstone and slate intercalated with coal seam rock group,marble,limestone intercalated with schist rock group,schist,siliceous rock,sandstone and slate rock group,were the rock groups prone to hazards.Distances to faults and rivers less than 1 km were both the susceptible zones of hazards.Among the above,elevation of[2672,3000)m,slope angle of[25,35)°,and slope aspect of SW,carbonate rock group,sandstone and slate intercalated with coal seam rock group were the areas of factors that most prone to hazards.The influence of the selected six factors on slope geohazards was as follows:elevation,rock group,slope angle,distance to water system,distance to fault and slope aspect,among which the first five factors were the main controlling factors of hazards.The research results provide a scientific basis for the prevention and mitigation of geohazards in the Nujiang River basin section of Sichuan-Xizang traffic corridor.