| Guizhou is rich in energy and mineral resources,with extensive mining methods in some mines.During production,a large number of tailings,industrial waste,production wastewater and other wastewater are produced in the mine,which brings about pollution risk to groundwater.A large number of mines are shut down due to rectification and resource exhaustion,and the operation of tunnel maintenance,suction and drainage is stopped.Goafs and tunnels have become the natural reaction environment of minerals,causing serious groundwater pollution.The karst aquifer in Guizhou is well developed and the distribution of underground river channel is not clear.The pollution path of karst groundwater is unclear,the source is complex and the prevention and control is difficult.This paper chooses two different groundwater pollution systems of Baishahe closed pit coal mine and SWK gold mine in karst mountainous area of Guizhou Province for pollution control research.The main research contents and conclusions are as follows.(1)Through surface investigation,comprehensive geophysical prospecting,drilling and connection test,the groundwater pollution and goaf characteristics of Baishahe closed pit coal mine are investigated.Through field surface reconnaissance,the pollution and collapse status of each spring point in the mining area are counted,and the geological points such as spring point and collapse are precisely positioned by surface aerial survey,which provides data support for later three-dimensional highprecision surface model.The comprehensive geophysical exploration method is used to detect the goaf,assisted by borehole verification to conjecture the goaf,obtaining comprehensive distribution map of data goaf and detection goaf;Contamination point traceability is carried out by combining charging method and borehole connection test.(2)Due to the lack of modeling data such as borehole data and geological profile data in closed pit mines,the goaf is characterized by comprehensive geophysical interpretation.Comprehensive drilling data,geological profile extraction of virtual drilling,surface aerial survey data to establish a three-dimensional stratigraphic model of the mining area;Extracting section coal seam information for depth constraints,and planar constraints on the goaf range to obtain a goaf model;Based on the field survey and statistics of multi-source geological data,a three-dimensional model for the fusion of multi-source data such as terrain,strata,mined out areas,and pollution points in the Baishahe closed pit mine is established through EVS,and a hydrogeological conceptual model for the southern and northern polluted areas of the mining area is constructed.Numerical simulation of groundwater was carried out on typical sections to clarify the characteristics of groundwater recharge,runoff,and drainage,and the suitability of treatment methods such as plugging connecting roadways and continuous alkali production infiltration curtain walls was analyzed.In general,a three-dimensional geological model construction and groundwater geophysical exploration and prevention analysis method for closed pit mines with insufficient data have been developed to address the issue of groundwater pollution prevention.(3)Surface reconnaissance,unmanned aerial vehicle measurement,water inflow point measurement,surface penetration coefficient measurement,various geophysical prospecting and connection test are carried out for SWK metal mines being produced.Through detailed surface reconnaissance and surface aerial survey,the geological conditions such as karst and structural surface development,mountain crevices,interception and drainage works in the mining area and its surrounding areas are determined.Flow test of underground middle section and surface underground river outlet has been carried out.The results show that surface rainfall recharge is obvious in the middle section of underground first,second and third mining and lateral stratum recharge is not strong.The degree of groundwater recharged by surface rainfall is quantified by surface infiltration coefficient test.The distribution characteristics of faults and underground rivers in the mining area have been explored by means of geophysical prospecting.Based on various geophysical prospecting,tracing test and flow test,it is proved that the karst outlet in the first and middle section of the well is related to the K20 falling water tunnel.Atmospheric rainfall is discharged from the karst outlet in the first and middle section of the well through the K20 falling water tunnel.(4)Faults and folds are well developed in SWK metal mines with complex geological conditions.However,the mine has modeling data such as intensive exploration borehole data and exploration line profile,which provide support for precise characterization of strata in complex structural zones in the mine area.The complicated problem of constructing complex structural three-dimensional geological model by EVS is solved by partition and zoning modeling.The suitability of various modeling software for fine modeling of different geological conditions is compared,and topographic and surface image maps,geophysical data,ore body,tunnel,goaf,goaf and so on are formed.Fault network model and construction method of 3-D geological model based on multi-source data fusion of strata.Based on the fine three-dimensional geological model constructed by intensive exploration boreholes,the geophysical inversion anomaly is developed from the traditional plane analysis method to the spatial analysis method based on the fine three-dimensional geological model,the spatial distribution of fault fracture zone and limestone strata in the mining area is identified,and the correlation between K20 falling water tunnel and karst outlet in the middle section is confirmed.Based on geophysical inversion data,accurate extrapolation of T1y2 limestone formation model and construction of underground river pipeline model are carried out,and fine three-dimensional geological model of mining area-fine interpretation and modeling method of mutual feed of geophysical exploration results is established.(5)The groundwater movement in SWK production mine was simulated by numerical simulation.Groundwater simulation is carried out under the condition that surface rainfall in production mines recharges groundwater through karst pipelines and the mine is continuously pumped and drained and overall dried.The simulation shows that the response of mine water inflow to atmospheric rainfall is obvious,while the atmospheric rainfall collected in the depression recharges groundwater through the K20 Falling Tunnel.The analysis shows that the daily average sewage treatment capacity of1300m3 can be reduced by setting interception and drainage works to divert the lowlying catchment water to the outside of the mining area through source blocking control. |
