Occurrence Of 'Mining-dewatering Induced' Water Cycle Of Concealed Karst Aquifers At Chensilou Coal Mine

As the shallow coal seams are depleted,most of the mines in the eastern mining areas in China have gradually entered the stage of deep mining.As a major measure for the prevention and treatment of deep karst water,the floor grouting technology is widely used.However,for a long time,the effect of hole deviation in the grouting holes on the groundwater circulation in the mining area has not attracted the attention of scholars.Taking the Chensilou mine in Yongcheng city,Henan province as an example,for 15 years since the floor grouting operation was implemented,the concealed karst aquifers at Chensilou coal mine has formed the “Mining-dewatering induced" water cycle under the mining disturbance.Hydrological observation hole,grouting hole exposing water level and hydrochemical and isotopic analysis show that the background of low upper and lower upper lower and weak hydraulic contact of each layer under the long-term mining disturbance has changed into the reverse "Mining-dewatering induced" water cycle,which is recharged from the east to the West.Kong Xie and lithology analysis indicate that the "hard and soft" lithologic combination of the bottom plate is the main reason for the depth error of the grouting hole to reach 30.9m.Grouting hole under the effect of hole inclination of taiyuan formation in the strong hydrophobic effect,and the integrity of floor strata damage,combined with the interlaminar fracture between karst limestone and water-resisting layer,along with mining disturbance under the error of grouting hole,finally forms the bottom-up guide water channel,deep aquifer in turn supply the upper aquifer,forming " Mining-dewatering induced " water cycle.Visual MODFLOW is used to simulate in three stages according to the actual mining process.Different pumping wells and permeability coefficients are set in different stages to simulate different mining conditions.The comparison and analysis of the simulation results at each stage shows that the formation process of the water cycle of concealed karst aquifers at coal mine is divided into three stages,that is during the period of construction and blasting,a small amount of dredging and grouting in the face of the working face slab were strongly staged during the early stage of the grouting of the upper part of the Taiyuan Formation and in the later stage of the bottom grouting transformation..The study shows that a large number of grouting holes have an important role in the deep karst water cycle.Combined with different hydrogeological backgrounds,the analysis of the specific hydrogeological effects is of great significance to the safe mining of mines.