重庆市龙泉村—庆丰山村岩溶塌陷分布规律与成因机制

文章以地质环境与隧道建设活动为基础，总结出重庆市沙坪坝区龙泉村—庆丰山村岩溶塌陷分布规律及发育特征:（1）岩溶塌陷集中分布于槽谷与横向冲沟交汇地带、槽谷中地势低洼地带以及地表溪沟附近；（2）岩溶塌陷形成演化呈现从地势低洼处往高处扩展、从隧道疏干区核心部位往边缘外围逐渐扩展的特征。研究区岩溶塌陷受隧道施工疏干排水及降雨影响控制，为隧道施工疏干后期降雨型岩溶塌陷。研究区岩溶塌陷的形成演化可分为三个阶段，其中前两个阶段为塌陷高峰期。不同阶段诱发岩溶塌陷的主控因素不同:第一、第三阶段主控因素为渗流潜蚀、增荷软化效应；第二阶段主控因素为渗流潜蚀及岩溶管道水气压力突变效应。

Distribution law and genetic mechanism of karst collapse in Longquan village-Qingfengshan village,Chongqing

Located in Longquan village and Qingfengshan village， Zhongliang mountain， Chongqing， the study area is a geologically hazard area of karst collapse induced by the construction of Tuzhu tunnel. A total of 45 collapse pits developed in the area， which seriously endanger the safety of roads， houses， pipelines and villagers' lives. In order to find out the distribution law and genetic mechanism of karst collapse in the study area， this paper systematically studies the karst collapse by carrying out a number of work， such as special ground investigation， geophysical exploration， geological drilling of hydrogeological engineering and dynamic condition monitoring of karst collapse， and summarizes the distribution law and development characteristics of karst collapse in the study area， showing as follows， （1） Karst collapses mainly distribute in the intersection zone of trough and transverse gullies， low-lying areas or the surface along stream； （2） The formation and evolution of karst collapse shows the characteristics of expanding from low-lying place to high place， and gradually expanding from the core of tunnel drainage area to the periphery of the edge.Based on the analysis of the influencing factors of karst collapse， the formation and evolution of karst collapse in the study area is divided into three stages， the first two of which are at the peak of collapse. The main controlling factors inducing karst collapse are different in each stage. In the first stage， the karst collapse is mainly controlled by the effect of seepage subsurface erosion， and increasing load and softening effect. The sudden change of water and gas pressure in karst pipeline system is the secondary factor. In the second stage， the karst collapse is mainly controlled by the effect of seepage subsurface erosion and sudden change effect of water and gas pressure in karst pipeline system， and the increasing load and softening effect is the secondary factor. The collapse in this stage is characterized by a large number of relatively simultaneous occurrence . In the third stage， the karst collapse is mainly controlled by the effect of seepage subsurface erosion， increasing load and softening effect. The sudden change of water and gas pressure in karst pipeline system is the secondary factor.A comprehensive analysis shows that the karst collapse in the study area is rainfall karst collapse in the later stage of tunnel drainage. The precondition is that the regional groundwater level drops below the bedrock surface due to tunnel drainage. The main dynamic factors are the infiltration and seepage subsurface erosion caused by rainfall， the sudden change effect of water and gas pressure in karst pipeline system and the increasing load and softening effect. The formation and evolution process of karst collapse can be generalized as follows， rainfall → slope flow → surface ponding → increasing load and softening effect / seepage subsurface erosion / sudden change of water and gas pressure in karst pipeline system → soil collapse → soil cave expansion → karst collapse.