| LeiXi gypsum mine is located in jiangxi province help LeiXi township, a long wall mining operation room and pillar mining method, began production in June 2000. Mining area in 2010 started to ground subsidence disaster, as of September 2013, mining area, a total of three subsidence area, the C1 subsidence zone of 11340m2, C2 subsidence zone of 9890m2,C3 subsidence zone is relatively small for 2350m2, of residents in the area of personal and property safety constitute a great threat.Taking LeiXi gypsum mine in jiangxi province as the research object, based on the basic analysis of geological conditions in the mining area, the surface deformation characteristics of mining ground subsidence areas and the goaf pillar and roof deformation characteristics of the system research. Mainly according to the characteristics of surface subsidence and the deformation of underground goaf pillar, the relationship between time and space analysis of the mining area ground subsidence influencing factors and formation mechanism, the concept of mining area land subsidence model is established, and uses the Midas finite element software to simulate the mechanism of ground subsidence, the mining area based on this, puts forward the prevention measures of the ground subsidence in the mining area.Through analyzing three LeiXi gypsum mine exploration of subsidence area, the system to find out the three LeiXi gypsum mine goaf pillar and roof subsidence of ground surface deformation characteristics and deformation characteristics, it is concluded that surface subsidence cracks mainly oval distribution at the center of the subsidence, deformation and damage of goaf pillar and roof and surface subsidence deformation in space have strict correspondence.According to the geological conditions of mining area, the surface deformation and subsidence area, the relationship between time and space of underground goaf pillar deformation control the ground subsidence and subsidence mechanism were analyzed. Reached the ground subsidence is under the condition of the goaf, goaf adjustment of in-situ stress of rock mass, pillar under the action of compressive stress in the roof, and in the long-term groundwater erosion under the action of deformation and failure occurs, resulting in nearly horizontal roof strata bend cracking and ground subsidence. And according to the mechanics analysis, only when more than 3 row spike occurred damage (the gob span of about 40m), might have the ground subsidence. On this basis, combined with the feature of mining area land subsidence, the establishment of the ground subsidence LeiXi gypsum mine geological mechanics model, and made the numerical simulation of the subsidence mechanism for validation.Numerical simulation results show that at the early stage of the decrease of strength of pillar, the pillar itself and the overlying rock mass can still maintain good integrity, but the intensity is reduced to a certain degree (70～80%) in the model, and the subsidence range is expanded to a certain degree, its rate of change of displacement will increase sharply, leading to the whole area of rock mass strength fell sharply. Calculation results show that the decrease of strength of pillar for the influence of ground subsidence is greater than the decrease of strength of roof strata and the effect of spike year-on-year reduction of displacement is about the decrease of strength of roof strata lead to the displacement of the subsidence 2 times. Which can be speculated that goaf pillar deformation and failure is the key cause of the ground subsidence disaster.For the above on the basis of the researches on the mechanism of the ground subsidence, targeted LeiXi gypsum mining ground subsidence prevention measures are put forward, and the prevention and control "governance is given priority to, combined with" for managing the overall plan of the ground subsidence in mining area, mainly uses the method of mining subsidence and filling method for processing, and through the pillar reinforcement method to prevent the not present subsidence mined-out area. |
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