Study On Surface Movement Parameters Of Repeated Mining Under Thick Alluvium

Coal resources,as China main supporting energy,provide favorable guarantees for the rapid economic development.The exploitation of high-strength,large-scale coal resources has gradually increased the depth of mining in eastern China’s mining areas,superimposed settlement of surface caused by repeated mining of multiple coal seams.The geological conditions of thick alluvium make the surface deformation law more complex,bring about a large number of unstable coal mining subsidences District,has a great threat to the ecological and environment.In order to study the effect of repeated mining of multi-coal seams under thick alluvium on the surface movement,combined with the geological mining conditions in Huainan mining area,on the basis of analyzing the movement and deformation laws of the surface of the Guqiao coal mine,the FLAC3D was used for the vertical repetitive mining conditions of the working face.The software establishes a numerical simulation model,studies the surface deformation law of repeated mining,establishes the relationship model between surface deformation parameters and the number of mining times,and analyzes the main influencing factors of surface deformation research shows:(1)The ground surface deformation under the condition of thick alluvium basically conforms to the mining law under general geological mining conditions,that is,the surface subsidence curve and the horizontal displacement curve are symmetrical and antisymmetric with respect to the center of the goaf.When the number of mining increases The surface subsidence basin becomes steep and the area of the subsidence basin increases slightly.(2)The subsidence factor is larger than 1 due to the effect of the thick alluvium structure,and shows a linear increase trend.However,after the third mining,the alluvium has been compacted,the subsidence factor tends to be stable and no longer increases with the number of mining While the displacement factor of the ground surface is basically stable without being affected by the repeated mining and has no obvious correlation with the number of mining operations.(3)After supercritical mining,the range of subsidence basin no longer increases.However,influenced by the increase of mining depth,the tangent of main effect angle and the limit angle with the number of mining moves increases linearly.(4)The surface deformation caused by repeated mining under the condition of thick alluvium is mainly caused by the coupling of the compaction degree of loose soil layers,the multiple expansion of rock fissures,the gradual deepening of mining depth,and the coupling of geological mining conditions with the mining times,resulting in the instability of surface subsidence areas The above results provide a theoretical basis for studying the law of surface movement in the process of repeated mining of thick alluvium and provide a technical reference for the treatment of ecological environment in non-steady and heavy mining subsidence areas in eastern China.