Study on overburden caving law in segmented mining of near vertical ultra-thick coal seam
Due to the special mining mode of near vertical ultra-thick coal seam,the development law of overburden caving and fissure in goaf is different from that of horizontal coal seam.Similar material simulation experiment was used to study the caving law of overlying rock in gob area of near vertical coal seam.PFC3D software was used to simulate the surface settlement and fracture development after stable mining in different level sections.The porosity evolution law was quantitatively analyzed,and the surface settlement law was further explored.The simulation experiment of similar materials found that with the progress of segmented mining,the overlying strata gradually collapsed,forming firstly a"U-shaped"area and then a"V-shaped"caving structure.The numerical simulation results show that with the progress of mining,the small amount of space left at both ends of the goaf gradually disappears,and the cracks in the goaf are connected with the surface,forming air leakage channels in the goaf.The caving law of overlying rock is consistent with the results of similar material experiments.The porosity of the goaf was stable between 0.30～0.65,and the porosity of the cracks on the top and bottom sides gradually increased,and finally stabilized at about 0.30.After the collapse,the width of the surface settlement gradually increased from 92.93 m to 100.16 m,and the depth greatly increased from 27.85 m,and finally stabilized at 101.63 m.The research results can provide reference for the mining design and safe production of near vertical coal seam.
near vertical coal seamsegmented miningoverburden cavingsimilar material simulationPFC simulation
万方数据
维普
