基于ArcGIS的易滑地层滑坡孕灾模式研究——以湖北省保康县为例

湖北省保康县滑坡灾害发育,查明滑坡的孕灾模式十分必要。通过分析滑坡分布发育特征,选取高程分布、水系分布、岩土体类型、降水、断层分布和人类活动6个因子,基于Arc GIS操作平台进行因子敏感性分析,进而识别出研究区易滑地层。在此基础上,提取出非连续变量孕灾模式:孕灾模式A,含碎石粉质黏土+基岩为碎屑岩;孕灾模式B,含碎石粉质黏土+基岩为碳酸盐岩。采用确定性系数(CF)法识别出连续变量孕灾模式:滑坡发育面积多为1.2万~4.8万m~2,滑坡后缘高程主要集中在280~520 m高程段,总体坡度19°~31°,且发育岩层倾角9°~36°。综合以上变量,获得研究区易滑地层滑坡典型孕灾模式,可划分为2个大类和6个亚类,即基岩为碎屑岩类(根据不同斜坡结构又可细分为3类)和基岩为碳酸盐岩类(根据不同斜坡结构又可细分为3类),滑体物质成分均为含碎石粉质黏土。研究结果可为保康县滑坡灾害防治提供一定的地质依据。

Study on landslide forming pattern of slide-prone stratum in Baokang County,Hubei Province,based on ArcGIS

There are 264 landslides developed in Baokang County, posing potential threat to the safety of the local society, thus it’s very necessary to study the landslide forming pattern of slide-prone stratum. According to the landslide distribution and development characteristics, 6 factors including distribution elevation, water system distribution, rock and soil types, precipitation, fault distribution and human activities, are selected to identify slide-prone stratum through factor sensitivity analysis based on ArcGIS platform. Based on the statistical analysis, two disaster forming pattern of discontinuous variables are extracted as: pattern A, gravel-containing silty clay and clastic bedrock; pattern B, gravel-containing silty clay and carbonate bedrock. The deterministic coefficient method is used to identify the continuous variable forming pattern and it is concluded that the areas of most landslides are 12 000 to 48 000 m2, and the rear edges of the landslides are mainly concentrated in the elevation of 280~520 m, the slope is 19° to 31° and the strata dip angle is 9° to 36°. Based on the above variables, the typical disaster forming pattern of the landslide in the study area can be divided into two categories and six subclasses: three clastic bedrocks and three carbonate bedrocks. The results can provide some geological basis for the prevention and control of the landslide in Baokang County.