宣汉地区降雨型滑坡空间发育规律及敏感性分析

宣汉县是四川省达州市地质灾害较为发育的县区。为研究该区域滑坡分布及稳定性规律,通过实地调查滑坡数据信息,并结合GIS技术和确定性系数法,分析与滑坡分布及稳定性紧密关联的多个致灾因子(滑坡坡度、高程、坡向、岩性、水系和公路)的敏感性。结果表明研究区滑坡灾害受到致灾因子影响区间多发生在:①400～1 000 m的高程范围内,其中400～600 m处于高度易发区;②滑坡坡度处于5°～25°的相对区间内,其中5°～15°区间更加敏感;③水系缓冲区和公路缓冲区均在800 m范围内,特别是公路缓冲区在400 m范围内的影响更大。同时,应用敏感性系数比值和敏感性指数进一步分析了致灾因子对滑坡分布和稳定性2个方面的影响程度。分析表明:坡度因子对降雨型滑坡稳定性起到重要的影响,但其对滑坡分布的影响程度要弱于公路因子。研究结果为今后类似条件下的滑坡危险性评价、防灾减灾计划等提供理论依托。

Spatial Development Law and Sensitivity Analysis of Rainfall-induced Landslide in Xuanhan County

Xuanhan County is a region with well-developed geological hazard in Dazhou,Sichuan Province.To study the distribution and stability of landslides in this region,we analyzed the sensitivity of hazard-inducing factors close-ly related to landslide distribution and stability, inclusive of slope gradient, elevation, slope direction, lithology, water system and traffic road,in association with GIS technology and certainty factor based on field survey. Results conclude that landslide is mostly affected in 1) elevation between 400-1 000 m,mainly at 400-600 m;2) slope gradient between 5°-25°,mainly at 5°-15°;3) 800 m from water and road buffer zones, especially 400 m from road buffer zone. Furthermore,we adopted the susceptibility coefficient ratio and the susceptibility index to further analyze the influence of the factors on the distribution and stability of landslide. Result shows that slope gradient factor plays an important role in the stability of rainfall-induced landslide,but its influence on landslide distribution is weaker than that of traffic road factor.