Study On Deformation Control Mechanism Of Shaft Under Solid Backfilling Mining In Ultra Close Multiple-seams

In order to meet the needs of protecting coal pillar recovery and mine safety,based on the protection of coal pillars in nantun coal mine industrial square,this paper systematically studies the deformation rule and control mechanism of shaft under backfilling mining by means of physical simulation,mechanical analysis and numerical simulation.Firstly,the main deformation and failure forms of the shaft in the process of recovery and protection of coal pillar by backfilling and collapse are analyzed by physical simulation.Through numerical simulation,the rule of controlling shaft deformation by compression ratio of ultra close multiple-seams coal seam is analyzed.Finally,according to the mechanical analysis,the critical enrichment ratio and numerical simulation control shaft deformation rule under Nantun backfilling condition are obtained.In order to test the feasibility of the backfilling scheme,the deformation of the shaft under the scheme is predicted and analyzed.In this paper,some research results have been obtained for Nantun coal,which are mainly reflected in the following aspects:(1)Based on the physical similarity model of backfilling and caving under repeated mining of ultra close multiple-seams,the flow law,deformation characteristics and stress variation characteristics of shaft under two mining conditions were compared and analyzed,the mechanism of controlling shaft deformation was revealed.(2)According to the deformation characteristics of the shaft in the process of mining,the corresponding mechanical model is established,based on the propagation law of the mining influence in the interior of the rock mass and combined with the theory of “equivalent mining height” for backfilling mining.The expression of displacement field,deformation field and stress field of rock mass under backfilling mining condition and the mechanical calculation formula of the critical enrichment ratio of deformation of shaft controlled by backfilling are deduced(3)Using ABAQUS numerical simulation software,the characteristics of shaft deformation and stress distribution under different enrichment rates were studied,and the law of coordinated control of shaft deformation in the upper and lower coal seams was revealed.It provides an important theoretical basis for the design of the enrichment rate of shaft deformation control in coal seam backfilling mining.(4)On the basis of the optimal design enrichment rate scheme,a probabilistic method is used to predict the shaft deformation under the scheme to verify the numerical simulation results.The maximum value of vertical compression deformation of the shaft is 1.85 mm/m and the maximum of tilt deformation of the shaft is 0.35 mm/m,which does not exceed the shaft fortification standard.