Evaluation on floor water inrush danger of Weibei during mining over pressurized water and prevention countermeasures to the water disaster

With increasingly high comprehensive mining intensity to the coal resources and wider mining width of the mining area, the mines of Chenghe No.2 mineral are getting deeper and deeper and the hazard from the high pressure water of Ordovician limestone of #5 coal bed bottom is getting increasingly intense, which will seriously influence safety production of the mines. Therefore, how to liberate the under draught coal reserves of #5 water body is a difficult problem as well as the key issue to ensure safety production of the mines. As for this, the first author will combine with the hydrogeological condition of Chenghe No.2 mineral in this article, and adopt standardized water bursting coefficient method to evaluate the water insulation capability of Taiyuan formation #5 coal floor upon comprehensive analysis on influencing factors of floor water inrush, to consider whether to divide #5 coal floor under waterdiversion failing zone thickness into different compensated mining areas, having predicted water inrush probability of the mining area in the future, and to release the coal reserves threatened by Ordovician water disaster. The result shows: (1) Among the factors that influence #5 coal floor water inrush of Chenghe No.2 mineral, head pressure of the aquifer is motive power of water inrush, the floor strata lithology and its combination feature are safety barrier for confined water extraction, and geological structure is in most cases the channel of floor water inrush; in accordance with the latest stipulations on mine water prevention and control and design specifications on coal mine water prevention, the first author takes 0.06MPa/m and 0.1MPa/m as boundary conditions of critical water inrush coefficient, divides #5 coal floor water-resisting layer into compensated mining extremely dangerous zone, dangerous zone and exploitable zone; (2) As to areas that mining above the pressured water are inapplicable in consideration of the coal floor water-diversion failing zone, latest water bursting coefficient formula can be adopted to realize safe compensated mining, which has reduced danger of floor water inrush, and satisfied the requirements of safe compensated mining of this mining area; (3) Without considering condition of the water-diversion failing zone, it can liberate compressed coal reserves of #5 coal floor that are threatened by Ordovician limestone water disaster and enhance the recovery ratio of coal resources; (4) Based on the evaluation results of floor water inrush danger, the author has proposed major water disasters to the coal floor and prevention countermeasures, which has provided valuable reference for safety compensated coal mining above seam floor pressure-bearing water body of Chenghe minerals and even Weibei coalfield, brought tremendous social and economic benefits, is of practical significance for realization of green coal mining, and will drive local economic development, thus worth being generalized and applied. © 2018 Books and Journals Private Ltd. All rights reserved.