Study on stereoscopic prevention and control technology of roof water disaster in contiguous coal seam in deep mines of Inner Mongolia and Shaanxi

In view of the complex hydrogeological conditions of the deep Jurassic coal seam mining in Ineer Mongolia-Shaanxi area, the mine is faced with problems such as difficult drainage of roof, high pressure of drainage system, low excavation efficiency and poor economic benefits during the mining. The water hazard prevention and control idea of “low-position adjacent face interception, prevention and control by zones, management by layers and groups” was put forward. The three-dimensional prevention and control scheme of roof water hazard in close distance coal seam and the evaluation system of three-dimensional prevention and control effect based on water inflow of single hole, water pressure of borehole and static reserve were established. Taking the short-distance mining roof water hazard prevention in Menkeqing Mines 3-1 and 2-2 of the Hujierte Mining Area as an example,fine exploration was carried out by means of up-down drilling and geophysical prospecting, etc., and the up-down well hydrological monitoring system was established and improved. On the basis of analyzing and studying important hydrogeological parameters such as the geological distribution of the aquifer-containing layer on the roof of the mine, the distribution range of anomalous water-rich areas, and the characteristics of the interval and groundwater flow field, the upward mining method was implemented. First, the roof drainage of the 3-1 coal of 3101 working face was carried out in a targeted manner, and the water inflow of the working face was accurately predicted through the drainage test, and a complete and reliable drainage system was established. The cumulative drainage volume of water drainage boreholes reached 26.59 million m?. During the excavation of 2201 working face, it was discovered through advanced water-discharging drill holes that,the water pressure and water quantity of the roof aquifer decreased to varying degrees compared with that of coal 3-1, indicating that the water content of the roof aquifer of coal 2-2 was reduced by cutting off the flow of coal 3-1 in the lower layer in advance, and the water damage prevention scheme has achieved preliminary effects. Before mining at the 2201 working face, combined with the sedimentary geological analysis and the delineated range of geophysical anomaly areas, the drainage work of roof water in key areas and layers was carried out to further optimize the design of drilling holes for roof water drainage. According to the water quantity and water pressure of each final hole, the water richness of coal roof aquifer in 2-2 decreased significantly. All these indicate that the proposed method of controlling roof water damage on a large scale by region and coal group, formed a three-dimensional prevention and control technology for roof water damage in deep coal mines in Inner Mongolia and Shaanxi, which is beneficial to the prevention and control of roof water damage in close range coal seams.