Study On Groundwater Drainage Technology Of Baotashan Sandstone Aquifer In New Shanghai No.1 Coal Mine

Ningdong coalfield mainly develops Jurassic coal seams,and the aquifer of Baotashan sandstone of Yan'an formation is the main water filling source affecting the mining of the lower coal formation.New Shanghai No.1 coal mine locats in shanghaimiao mining area of Ningdong coalfield in the western margin of Ordos Basin,which is subordinate to Otog Front Banner of Ordos City.The No:18 coal seam is threatened by the aquifer of Baotashan sandstone.The aquifer of Baotashan sandstone has strong water yield and abundant static reserves.Due to the thin aquifuge and high pressure between the No:18 coal seam and the aquifer of Baotashan sandstoner,the water inrush coefficient of the No.18 coal mine seam is greater than0.1MPa/m,which shows that there is a danger of floor water inrush in all working faces of the No.18 coal mine seam.Owing to the water inrush accident by the aquifer of Baotashan sandstone in new Shanghai No.1 coal mine,it is decided to carry out the special research on the aquifer of Baotashan sandstone to ensure the safe mining of No.18 coal mine seam.This paper,took the new Shanghai No.1 Coal Mine as the research area,based on the hydrogeological conditions of the aquifer of Baotashan sandstone and underground water drainage test,focused on the study of hydrogeological characteristics,through the construction of groundwater flow numerical model to demonstrate the feasibility of drainage of the aquifer of Baotashan sandstone,and established the drainage optimization management model.Finally,the optimal draining management scheme was proposed.The main achievements were as follows:1)Based on the geological and hydrogeological conditions of new Shanghai No.1coal mine,the characteristics of lithology structure,pore structure,aquifer thickness and disintegration resistance of Baotashan sandstone aquifer were studied.The hydraulic connection between Baotashan sandstone aquifer and other aquifers,fault hydraulic conductivity,groundwater recharge,runoff and drainage conditions,water yield and hydrochemical characteristics were analyzed.It was considered that the aquifer was characterized by the complex sedimentary environment,strong water yield and abundant static reserves,high water head and limited recharge.2)Based on the analysis of hydrogeological characteristics combined with water discharge test as the basic conditions and data,a three-dimensional numerical model of groundwater was established by GMS.Through the model identification and verification,the calculated flow field had a high fitting with the measured flow field at the end time,the hydrogeological parameters were more accurate,which provided a good foundation for the next research.3)The feasibility of drainage of the aquifer of Baotashan sandstone was evaluated based on the hydrogeological conditions,the results of drainage test,pumping test and numerical simulation.It was concluded that the static reserve of the aquifer of Baotashan sandstone was large,the external supply was limited,and it belonged to the relatively closed hydrogeological block.The method of the drainage was feasible.4)Based on the simulation model,took the minimum amount of drainage and draininging time as the goal,and the safe mining water level,single hole drainage and the maximum drainage capacity of the mine as the constraint conditions,the optimal management model of groundwater drainage of the aquifer of Baotashan sandstone in Frist division of No:18 coal mine seam was established.Combined with the mining plan and drainage capacity of new Shanghai No.1 coal mine,a variety of optimized management schemes for groundwater drainage in Baotashan sandstone aquifer were designed.The results of optimization calculation showed that 12 drilling holes and180 days drainage were the most effective drainage measure.