Hydrogeology “double exploration and three prediction” technology of burnt rock and ancient gully area in open-pit

The water gushing area at the east end of the first mining area of an open-pit mine in Yulin City is located in the burnt rock and ancient gully area, the water resource reserves are huge, and the water gushing is obvious during the perforation, which brings huge potential safety hazard to the stripping of the mining pit.In order to ensure the safe production of the mining pit, the hydrogeological exploration work is carried out in the east end area.The “double exploration” technology of zonal geophysical exploration and drilling is used to explore the hydrogeological conditions.Combined with the drilling pumping test, the “three prediction” work of permeability coefficient, unit water inflow and regional water inflow is carried out.The results show that according to the geophysical exploration results of the east end of the first mining area of an open pit mine in Yulin City, the low resistance anomaly range of the ancient gully and burnt rock area is the largest, and the anomaly intensity show a very strong to strong trend, it is inferred that there is a water channel, which connects the upper aquifer with the lower aquifer, and the recharge source is rich, the water rich intensity is very strong.For the burnt rock and ancient gully development area, the burnt rock aquifer presents the characteristics of extremely high permeability and high water inflow, which indicates that the lower burnt rock has good connectivity and are of strong water abundance grade; the mixed section presents medium permeability coefficient and high water inflow, which indicates that the connectivity of rock strata in the middle mixed section is general, the water flow is rich, and the mixed section is also of strong water abundance grade.The large well method and water collecting Gallery method are used to predict the water inflow of the east end wall burnt rock area and the 206 m geophysical prospecting strong water rich area in the ancient gully development area, and the estimated water inflow is 6 453.78 m³/d.