Feasibility Analysis of Laying Metal Mesh Artificial False Roof in 14th Coal Seam Mining
The planned mining coal seams for the first mining area of Shengli Coal Mine are the 14th coal seam and the nearby underlying 15th coal seam.To ensure the safety of mining the 15th coal seam,it is proposed to lay a metal mesh on the roof of the working face to form an artificial false roof during the mining of the 14th coal seam.The reliability analysis of artificial false roof after the 14th coal mining is carried out,and the simply supported beam stability analysis method is used to determine the thickness of the artificial false roof limit state to be 5.74 m.According to hydrochemical experiments,it is concluded that the accumulated water in goaf is corrosive to the laying of metal mesh.It is analyzed that the effective occurrence time of the metal mesh laid in the goaf will not exceed 3 years.Combined with the analysis of the formation time of the regenerated roof,it is determined that when there is a layer spacing of more than 1 m between the 15th coal seam and the 14th coal seam,mining activities for the 15th coal need to be carried out at least 3.5 years after the completion of mining for the 14th coal seam;When the 15th coal seam merges with the 14th coal seam,mining activities for the 15th coal need to be carried out at least 5 years after the completion of mining for the 14th coal seam.