苏州市金庭镇蒋东岩溶塌陷地质条件及形成机理研究

Study on geological conditions and formation mechanism of karst collapse in Jiangdong Village,Jinting Town,Suzhou City

通过野外地质调查、钻探、岩土样品测试等手段,研究了苏州市金庭镇蒋东岩溶塌陷的地质条件及形成机理。蒋东碳酸盐岩质纯、层厚、岩溶发育程度高,第四系覆盖层较薄且遇水后力学强度大幅降低,这是塌陷形成的内在地质条件,矿山开采是塌陷形成的外在诱发因素。该塌陷模式可概化为真空吸蚀重力致塌,致塌力主要为溶洞管道内重力水流、水位快速下降产生的真空负压吸蚀力和覆盖层土体自重。根据塌陷区地质条件和诱发因素,建立了基于极限平衡理论的真空吸蚀重力致塌力学模型。模型计算结果表明,在真空吸蚀作用形成过程中,塌陷体的稳定系数K>1.0,必然产生剪切变形破坏,模型计算结果符合岩溶塌陷的实际情况。

By means of field geological survey,drilling,rock and soil sample testing,the geological conditions and formation mechanism of karst collapse in Jiangdong Village,Jinting Town,Suzhou City were studied in this paper.The carbonate rock in Jiangdong Village is characterized by pure quality,thick layers and high degree of karst development,with a relatively thin quaternary overburden of which the mechanical strength decreases greatly when it is exposed to water.These are internal geological conditions for the formation of karst collapse,and mining is the external inducing factor for the formation of collapse.The collapse model can be generalized as vacuum erosion-gravity collapse,which is mainly caused by vacuum negative pressure erosion-induced by gravity flow and rapid drop of water level in the cave pipe and the self-weight of overburden soil.According to the geological conditions and the induced factors of the collapsed area,a mechanical model of vacuum erosion-gravity induced collapse based on limit equilibrium theory was established.The calculation result of the model shows that the stability coefficient(K>1.0)of the collapsed body is bound to produce shear deformation and failure during the formation process of vacuum erosion.The model calculation result is in line with the actual situation of karst collapse.