| Floor water inrush is one of the main disasters in coal mines,which is very common in China's coal mines and has great influence on mine safety production.Therefore,it is of great significance to study the hydrogeology conditions and the feasibility evaluation of draining depressurization of the aquifer under the coal seam.Taking Xinshanghai No.1 Coal Mine in Inner Mongolia as an example,the hydrogeology conditions of sandstone aquifer in Baota Mountain under coal seam are studied.Through the single hole and multi hole underground dewatering tests,the hydraulic connection between each aquifer is analyzed,and the hydrogeological parameters of Baotashan sandstone aquifer are calculated.Through the establishment of three-dimensional groundwater flow numerical model,the feasibility of draining depressurization of underlying sandstone aquifer is quantitatively evaluated.In this paper,two dewatering tests of single hole and multi hole are carried out in Baotashan sandstone aquifer,and the law of water level change with time in each aquifer observation hole is obtained.According to the water level dynamic analysis of the observation data of the dewatering tests,there are observation holes in the Cretaceous,Zhiluo Formation and coal measure aquifers in the mine field,which have a good response to the dewatering tests,indicating that there is a certain degree of hydraulic connection among the Cretaceous,Zhiluo Formation,coal measure aquifers and the Baotashan sandstone aquifer.Based on the hydrochemical data of previous supplementary exploration and this dewatering test,the water chemical types,mineralization degree and p H value of each aquifer are analyzed,and clarified the relationship among recharge,runoff and discharge and the rule of groundwater migration;According to the water level data of the four observation holes nearest to the drainage hole in the single hole dewatering test,the hydrogeological parameters of Baotashan sandstone aquifer,such as hydraulic conductivity and water storage rate,are calculated by using the wiring method,linear graphic method and water level recovery test method.The hydraulic conductivity ranges from 0.90 to 1.76 m/d,and the water storage rate ranges from 1.9×10-6to 1.6×10-4m-1.Based on the analysis of the data of this dewatering test and the previous hydrological supplementary exploration pumping test,it is considered that the recharge of the sandstone aquifer in Baotashan is weak and easy to be drained;Using the MODFLOW module of GMS software to establish a three-dimensional groundwater numerical model of the study area,through generalizing the correct boundary conditions,setting and adjusting reasonable hydrogeological parameters,identifying the dewatering test data,the final value of the simulation calculation is basically consistent with the measured water level of each aquifer,which shows that the model can accurately describe the hydrogeological conditions of the actual study area.Using the established model,the existing drainage holes are used for pre drainage,and the drainage law of the study area is obtained.After that,six drainage schemes with 9?16drainage holes and water volume of 22500 m3/d?40000 m3/d were set up,and the predicted drainage time was>700 d?130 d.It is found that increasing the number of drainage wells all the time can accelerate the decline of groundwater level,but the drainage effect has not been increased equally.Therefore,the factors such as the amount of drainage,the number of drainage wells and the time of drainage should be taken into account in the actual drainage work. |
PDF Full Text Request