Analysis And Numerical Simulation Of Sinkhole Mechanism In Soil Stratum

Sinkhole happens when soil underground was taken away by natural factors or human activities. Nowadays the study of the sinkhole focuses on in-situ survey, mechanism anslysis, susceptibility, and numerical simulation. Physical model has not been made to predict the disaster. This thesis studys the sinkhole by applying plastic limited equilibrium theory, granular materials flow theory and numerical simulation, which are followed by the results.(1) In this thesis, the sinkholes have been classified in to6categories by summing up ideas of papers domestic and abroad. The purpose of this paper is to come up with models to predict the disasters.(2) A physical model of sinkhole in soft soil is made by applying plastic limited equilibrium theory, which brings the safety factor. Mathematical method is used to explain why sinkhole in soft soil often appears as a well form. The relationship between safety factor and parameters has been studied. The safety factor decreases when radius of fracture face, reduced factor of atmosphere pressure, and density of soil increase, and it increases when depth of cavity and cohesion of soil increase. Some of the sinkhole cases have been explained by the theory and some measures are pointed out.(3) Granular materials flow theory is used to explain sinkholes in giant grained soil stratum. The establishment of sinkhole model is followed by analysis of the developing procedure. The results show that sinkholes in gaint grained soil stratum developed very slowly at the beginning but very fast in the end. A function is pointed out to predict the disaster which can help to determine the sinkhole developing phase.(4) Numerical Simulation method is used to simulate the plastic zone and displacement field of the clay stratum cause by a cavity underground. Qualitive analysis of sinkhole in clay stratum has been made.