武汉白沙洲长江两岸岩溶塌陷易发性评价与地铁建设过程中的防治对策

近年来在武汉市城市工程建设过程中，岩溶塌陷时有发生，严重影响了城市建设发展和人民群众的生命财产安全。为查明岩溶区地面塌陷易发性分区情况并提出防治对策，以白沙洲岩溶条带长江两岸作为研究区，选择岩溶发育程度、土层厚度、土层结构、红层厚度、地下水水位波动、岩溶水水位波动部位、塌陷坑密度7个评价因子，采用层次分析法建立岩溶塌陷发育的多因子判别模型，并结合GIS空间分析技术将研究区划分出高、中等和低易发区域。针对区内地铁工程不同阶段特性及其位于不同的易发性区段，以地质结构为根据，提出了相应的防治对策和建议。结果表明:高易发区主要位于长江两岸覆盖型岩溶区，且多为含砂性土层；高易发区为防治的重点，规划阶段尽量回避此区，防治原则主要是阻止上覆砂颗粒的漏失。中等易发区防治原则是防止单一黏性土中土洞的形成和扩大及保护红层的完整性。低易发性区红层厚度大于工程施工进入基岩厚度，发生岩溶塌陷的可能性极小。本研究成果能为武汉长江两岸的工程建设提供参考。 

Evaluation of susceptibility to karst collapse on both sides of the Yangtze River in Baishazhou,Wuhan and preventive measures in the process of metro construction

In recent years, during urban engineering, there have been frequent karst collapses in Wuhan city, which seriously affects urban development and citizens security. In order to ascertain the susceptibility zone of ground collapse in karst area and put forward prevention measures, the Baishazhou karst belt along the Yangtze River is taken as the study area, and 7 indicators (karst development, soil thickness, soil structure, red-strata thickness, groundwater level fluctuations, karst water level fluctuation position and the density of collapse pit) are considered as evaluation factors. Based on this, a multi-factor discriminative model of karst collapse development is established employing analytic hierarchy process, and the study area is divided into different regions with high, medium and low susceptibility through GIS spatial analysis technology. Corresponding countermeasures and suggestion are proposed on the basis of geological structure for characteristics in different stages of the subway project in the region and their different sections of the susceptibility. The result shows high-susceptibility parts are mainly located in the covered karst area on both sides of the Yangtze River, and mostly contain sandy soil. High-susceptibility parts are the key of prevention and treatment, therefore, this area should be avoided during the planning phase, and the principle of prevention and control is mainly to prevent the leakage of the overlying sand particles. The principle of moderately susceptible zoning prevention is to prevent the formation and development of soil cavities in a single clay soil and to protect the integrity of the red layer. The thickness of the red layer for low susceptibility is greater than that of the engineering construction entering the bedrock, and the possibility of karst collapse is minimal. Our study can provide a reference for the constructions on the banks of the Yangtze River in Baishazhou, Wuhan.