Study on overburden failure characteristics and water disaster prevention and control technology in fully mechanized extra thick coal seam in weak consolidated strata

In order to solve the problem of water disaster prevention and control in weakly consolidated extra thick coal seam under multiple aquifers, by using analogy analysis method, numerical simulation method and similar simulation method, and the overburden failure characteristics of layered mining in the top of Ⅱ₃ extra thick coal seam under the goaf of Lingdong Coal Mine are studied, and the development characteristics of water conducting fracture zone are analyzed.The method of “geophysical prospecting+drilling” is put forward to release the aquifer in the water conducting fracture zone in advance.The research results show that the overburden failure of the Ⅱ₂ extra thick coal seam overlying the Ⅱ₃ extra thick coal seam presents the characteristics of “ladder” collapse during mining.When the roof of the Ⅱ₃ extra thick coal seam is mined in layers, the overburden presents the phenomenon of bending and sinking in coordination with the interlayer strata of the Ⅱ_2-1 coal seam after the first pressure of the working face.It is estimated that the water conducting fracture zone has not affected the goaf of coal seam Ⅱ_2-1.The “audio frequency electric perspective and transient electromagnetic” is used to detect the water rich abnormal area containing water in goaf Yihan and Erhan(1).The drilling detection is focused on the water rich abnormal area, taking into account the non-water rich abnormal area, and finally the safe mining of the first mining face is realized.