Study on the Mechanism of Pressure Reduction in Gangue-Filled Mining and Sensitivity of Main Controlling Factors

Abstract Gangue-filled mining technology represents the significant advancement in green mining. To investigate the mechanism of pressure reduction in gangue-filled mining and the sensitivity of main controlling factors, the mechanical model was first developed based on the advanced support pressure in mining. The method for calculating mining pressure in filled mining was derived from beam structural stress characteristics. Then, numerical simulation methods were employed to analyze the pressure reduction patterns in gangue-filled mining based on the geological conditions. Finally, orthogonal experiments were conducted on main controlling factors, and sensitivity analysis was performed using range analysis and variance analysis to determine the sensitivity of each controlling factor. The results show that: (1) Pressure manifestation in gangue-filled mining is determined through main controlling factors including mining height, filling ratio, and gangue elastic modulus; (2) Under the support of coal gangue, the concentrated stress in the coal seam significantly decreases, forming an "arched" shape according to the construction stage; (3) The range of plastic failure in the coal seam remains relatively stable under filled mining and the plastic zone of the roof plate shows a strip-like distribution; (4) Range analysis and variance analysis revealed the sensitivity ranking as filling ratio > mining height > elastic modulus of the filling material. Variance analysis also indicates mining height and filling ratio have significant impacts on mining pressure, whereas the elastic modulus of coal gangue has a negligible impact.