PHYSICAL MODEL OF MUD-FLOW TYPE KARST GROUND COLLAPSE

In order to further study the occurrence conditions and mechanism of the Covered Karst Ground Collapse(CKGC),on the basis of Luo Xiaojie's theory about CKGC,the geological phenomena, geological model, physical model and mathematical expression of the mud-flow type ground collapse are studied. According to the characteristics of the kinematic response of soft soil and the deformation of surrounding soil during collapse, the geological model of mud-flow type karst collapse is established. The soft soil is regarded as high viscosity fluid based on its characteristics of higher water content and liquid limit, lower shear strength, flowablity, and it flows in laminar state in the course of collapse. A generalized physical model of the Mud-flow type ground collapse is proposed, the corresponding mathematical expressions are given according to the law of Newton inner friction and Limit Equilibrium Theory, the basic characteristics of Mud-flow type ground collapse is discussed.it is that Mud-flow type ground collapse will occur at a fixed rate, and the collapse speed is proportional to the square of the diameter of the karst channel, the density and natural moisture content of the soft soil, and is inversely proportional to the viscosity coefficient. the duration of the collapse is proportional to the coefficient of viscosity and thickness of the soft soil, is inversely proportional to the density of soft soil and the square of the diameter of the karst channel.