Analysis on Karst Cover Collapsing Mechanism Caused by Underground Coal Mining

In order to effectively predict and prevent the karst collapsing disaster caused by coal mining in underground mine located in China karst area, based on Pinghu Mine of Jiangxi Fengcheng Coal Mining Area as an engineering background, the numerical simulation, surface ground movement calculation and other methods were applied to analyze the mechanism and influence factors of the karst collapsing caused by the additional stress disturbance from the mining and to determine an ev aluation index of the karst collapsing probabllity.The study results showed that the underground mining would cause a tensile stress in the kart stratum and form a tensil e failure zone.As for a shallow covered karst cavity, the tensile failure zone would be developed to the surface ground and the karst cover collapsing would be formed.T he calculation and analysis on the surface ground movement showed that when the tensile deformation of the surface ground was over 1.8 mm/m, the karst cover would have a high possibility to collapse.In order to prevent the karst cover collapsing over the mining area, the survey on the karst stratum before mining and the prediction 0 f mining influences was necessary.