胜利煤矿一采区规划开采的煤层为14煤层和近距离下伏的15煤层,为确保在采15煤层的开采安全,提出在开采14煤层时工作面顶板铺设金属网形成人工假顶,对14煤开采后的人工假顶进行可靠性分析,采用简支梁稳定分析法,确定人工假顶极限状态的厚度为5.74m。根据水化学实验可得,采空区积水对铺设金属网有腐蚀性,分析采空区铺设的金属网有效赋存时间不超过3a。结合再生顶板形成时间分析确定,当15煤层与14煤层存在1m以上的层间距时,15煤至少需要在14煤层开采完毕3.5a后进行采掘活动;当15煤层与14煤层合层时,15煤至少需要在14煤层开采完毕5a后进行采掘活动。

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.