鲜水河是青藏高原隆起过程中沿鲜水断裂带形成的年轻河流，流域内新构造运动活跃、气候变化异常，是我国地质灾害高易发区，共发育各类地质灾害627处，具有显著的“线-带-片”空间特点；季节性、周期性等时间特点。基于1973年炉霍7.9级地震以来的调查资料，结合近5年来对流域内各县进行的1：5万地质灾害详查工作，对孕灾环境条件进行深入研究，得出的主要认识有：（1）地形地貌是地质灾害孕育的物理条件。高程控制人类居住与活动范围，控制气候、植被等垂直分带。斜坡坡度、坡型、坡体与岩体结构、沟谷微地貌控制不同类型、规模、稳定性或易发性的地质灾害。（2）地层岩性是地质灾害孕育的物质基础。不同的地层岩性、土石组成、内部结构、分布、物理力学特性，控制不同类型地质灾害。（3）地质构造、地震、活动断裂是地质灾害孕育的内动力条件。褶皱控制地形地貌，地质构造结构面控制岩土体变形破坏的空间位置和边界，地质构造控制山体斜坡地下水分布和运动规律，活动断层控制岩土体持续变形破坏时间。（4）降雨是地质灾害孕育的外动力诱发条件。降雨增加斜坡体自重、浸润斜坡的软弱结构面、降低斜坡稳定性，为泥石流形成提供水动力作用，是泥石流流体的重要组成。%Xianshui River is a young river along Xianshui River active faults and is formed during the process of the Qinghai-Tibet plateau uplifting.The river basin is a high easy-happening area to geohazards with activity neo-tectonic and climate abnormal change in our country,developes 627 all kinds of geohazards,which have line-belt-piece space and seasonal,cyclical,earthquake frequency periodic time characteristics.Environment pregnant of geohazards are deeply studied on account of combining with survey data after Luhuo great earthquake in 1973,and 1∶50000 detailed investigation work within nearly five years and the main consequences of this study are:(1 )To-pography is the physical condition of geological disaster breeds,which controls of human living and activities,cli-mate and vegetation vertical zoning.Slope gradient and type,slope and rock mass structure,valleys microrelief control different type,size,stability or liability geohazards.(2)Lithology is the material basis for the geohazards breeds,different formation lithology,rock composition and structure,distribution,mechanical properties control different geohazards.(3)Geological structures,earthquake,active faults,are endogenetic force for the geohazards breeds,folds control landform;fractures change rock mass structure;tectonic structural planes control spatial loca-tion and boundary of rock mass deformation and failure;geological structures control the distribution of the ground-water in the mountain slopes and motion;active faults control duration of rock mass deformation and failure.(4) Rainfall is force induced condition of geological disaster breeds,which increases rainfall slope body weight,infil-trates the slope of the weak structural plane,reduces the slope stability,provides hydrodynamic effect for formation of debris flow,is the important part of landslide body.
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