岩溶区诱发性土洞塌陷的水膜效应作用机理研究

Study on the Water Film Effect and Mechanism of Induced Soil Cave Collapse in Karst Area

岩溶区土洞塌陷是典型的诱发性地质灾害,其致灾过程具有强隐蔽性、难预测性、过程复杂性、群发性的特点。为研究其致塌作用过程与机理,以重庆典型岩溶区的诱发性土洞塌陷为研究对象,自制试验装置,现场采集盖层土样,开展地下工程诱发土洞塌陷物理模拟试验,采集了负压与盖层土体微应变信息,揭示了水膜效应在土洞塌陷过程中的作用机理。结果表明:在水位下降与降雨条件下,覆盖层土体在土洞正上方变形最大,并向边缘逐渐减小,且土体变形与土洞空腔内的负压值正相关,与厚度负相关。水膜效应是由水-土-气耦合作用导致,其加剧了土洞塌陷的风险,是岩溶区土洞成群成片致塌的内因,为该地区土洞塌陷的监测预警和治理对策提供了理论支撑。

Soil cave collapse in karst area is a typical induced geological disaster,and its disaster causing process has the characteristics of strong concealment,difficult prediction,complex process and mass occurrence.In order to study its collapse causing process and mechanism,the induced soil cave collapse in the typical karst area of Chongqing was taken as the research object,The self-made test device was used to carry out the physical simulation test of soil cave collapse induced by underground engineering.The negative pressure and the micro-strain information of the cover soil were collected,and the mechanism of water film effect in the process of soil cave collapse was revealed.The test results show that under the conditions of water level decline and rainfall,the deformation of overburden soil is the largest directly above the soil tunnel and gradually decreases to the periphery,and the soil deformation is positively correlated with the negative pressure value in the soil tunnel cavity and negatively correlated with the thickness.The water film effect is caused by water-soil-air coupling,which intensifies the risk of soil cave collapse.It is the internal cause of soil cave collapse in groups in karst area,and provides theoretical support for the monitoring,early warning and treatment countermeasures of soil cave collapse in this area.