Numerical Simulation Of Ground Fissures Induced By Mining

The rock has the low tensile strength mechanics characteristic, this characteristic initiation's project disaster is innumerable.The ground fissure in one of the ground distorts disaster which caused by rock projects.The mining coal depressed area often has massively the ground fissure, causes the environmental deterioration, the severely impair people's life and the property security. In the research coal mining causes the ground fissure process and the rule, has the important meaning in the project practice.Research the evolution process of ground fissure in mining subsidence area and the distribution law of ground fissure induced by mining. The main introduction rock layer migration destruction rule, the rock denaturation destroys mechanics analysis as well as the mining coal suggestion settlement crack's mechanics analysis and so on correlation theories, is pulled take the rock the destruction the theory as a foundation, gave the rock to pull the tension fracture four criteria, established the finite element model, the computation obtains the numerical simulation result, the result which the analysis simulation mining coal suggestion crack's evolutionary process and the surface burst.The finite element method is the present application most extensive research tool, but the traditional finite element method is established in the continuous supposition foundation, which cannot simulate the rock formation the uncontinuous structureto after tension fracture, cannot the direct processing rock tension destruction phenomenon question. Do the numerical simulation of the evolution process of ground fissure with different tensile strength, working surface advancement length, mining depth and inclination angle in mining subsidence area by using the finite element method describing tensile failure.The analogue result indicated: At the outer edge of subsidence area surface the ground fissures are formed and extended to depths after the goaf is damaged to certain degree with the propulsion of the working face.The tensile strength is smaller, the working surface advancement's length is bigger, the mining depth is smaller, the surface forms the crack increases. The cap rock tensile strength is smaller, the working surface advancement length is bigger, the coal bed burying depth is shallower, the surface is easier to form the settlement crack, even forms the fall of ground. The cracks in the earth sew on widely under narrow, the expansion direction is vertical approximately with the working surface advancement direction. Tocrack the occurrence and development process is the role of process in rock mechanics in the performance of tensile rupture of the formation of discontinuities, the cracks around the stress state changed, the cracking point the stress was released, the stress redistribution, resulting in the further expansion of the formation of the rock cracks secondary rupture, this process constantly repeated. Subsidence in the process of crack formation is the process of the formation of the new structure, the corresponding stress state leading to constant adjustment and change. The tension fracture finite element procedure to be possible provides the new method for the research mining coal suggestion crack mechanism and the crack expansion rule.