Study on the Hydrogeological Characteristics of the Roof Limestone Aquifer After Mining Damage in Karst Mining Areas

To study the phenomenon of abnormal water inrush in deep working faces during the process of coal production from coal mines in mining areas in karst landforms in Guizhou Province, project researchers collected data from 348 boreholes in the Xinhua mining area, Jinsha County, Guizhou Province, during the period of production in the mine. Aboveground and underground drilling, geophysical exploration techniques, empirical formulas, indoor simulations, and other methods were used to study the hydrogeological characteristics and water inrush channels of the Changxing Formation limestone in the mining In order to study the phenomenon of abnormal water burst in deep working faces during the production process of coal mines in karst landform mining regions in Guizhou Province, project researchers collected hydrogeological data from the explora-tion and production period of the Xinhua mining region in Jinsha County, Guizhou Province. Using ground and underground drilling, geophysical exploration techniques, empirical formulas, indoor material simulations methods, the hydrogeological evolution characteristics of the Changxing Formation limestone in the mining region after the mining damage of the 9# coal bed were studied. The research results indicate that the ra-tio of the height of the roof failure fracture zone measured by numerical simulation and ground borehole to the mining height is greater than 25.78 times, far greater than the empirical formula calculation value of 13.0-15.8. After the mining the underlying 9# coal bed, abnormal water rich area developed in the Changxing Formation limestone, and the mining damage fractures connected the original dissolution fissures and karst caves within the limestone, resulting in the weak water rich (permeable) aquifer of the Changxing Formation limestone becoming a strong water rich (permeable) aquifer, which became the water source for mine water burst. Furthermore, Over time, the voids in the Changxing Formation limestone after mining damage are gradually filled with various substances, resulting in a decrease in water storage space and connectivity, the specific yield decreases with the increase of water burst time and the interval between the cessation of mining in the supply area, and the correlation coefficient R is 0.964, in-dicating a high degree of correlation between the two.