线性工程岩溶塌陷危险性评价研究

近年来,越来越多的高等级公路、铁路、石油管线等线性工程穿越岩溶发育区,岩溶塌陷已成为这些线性工程建设面临的主要隐患之一。目前,线性工程项目前期都会进行全线地质灾害危险性评价工作,但大部分是定性的,也没有专门针对岩溶塌陷的评价,因此本文从岩溶塌陷的影响因素出发,结合线性工程的各个阶段,从点、线、面三个层次提出线性工程岩溶塌陷危险性评价的方法和指标,并列举了实例,为今后穿越岩溶区的线性工程提供借鉴。面上和线上评价充分利用GIS技术和层次分析法进行。前者适合于地质资料不详细的可行性研究阶段,评价区为线路两侧1km的区域,评价因子有岩溶发育程度、地质构造发育程度、地貌类型、岩溶塌陷、地下河、垂直型岩溶形态、岩溶泉和开采井分布。后者适合于地质资料较详细的初步设计阶段,评价区为线路两侧15m的范围,以基岩岩性、线岩溶率、土层厚度、土层性质、地下水位和地下水位与基岩面的关系作为评价因子。点上评价适合于重点地段,采用岩溶塌陷动力条件与土层抗塌性能相结合的综合分析方法,以反映地下水动力特征的临界坡降、临界速度和临界水位这3个指标作为评价因子。 

Study on the risk assessment on karst collapse in linear engineering

In recent years, more and more high-level linear engineering such as high-level road and railway as well as oil pipeline passes through karst area. Karst collapse has become one of the major hidden dangers having to be faced in the linear engineering in karst area. At present, a linear engineering project will conduct geological hazard zoning in the early phase. However, most of the works are qualitative and no special evalu- ation on karst collapse. Therefore, considering the influencing factors of karst collapse and different stage of linear engineering, different assessment methods and indicators are proposed from three levels, i.e. point, line and plane, and three examples are given at the same time, which will provide references for future linear projects that crossing the karst area. Plane and line assessment both use the Geographical Information System （GIS） and Analytic Hierarchy Process （AHP）. Plane assessment suits for the feasibility stage that geological data are not clear. Assessment area is 1 kilometer on both sides of the line and assessment factors are karst developed level, geological structure, landform type, sinkhole, subterranean river, vertical feature, karst spring and pumping wells distribution. Line assessment suits for preliminary design stage that geological data are clearer. Assessment area is 15 meters on both sides of the line and assessment factors are bed- rock lithology, line karst rate, soil thickness, soil properties, water level and relation between the water level and bedrock surface. And point assessment is suitable for the key sections, using the method of comprehensive analysis on the dynamic conditions of the karst collapse and the collapse resistance property of the earth. Three indexes, critical gradient, critical velocity and critical water level, which reflect the dynamic conditions of the groundwater, are used as the assessment factors.