| Wangwa Coal Mine is located in Guyuan City,Ningxia Hui Autonomous Region.When mining Jurassic coal seams,it is threatened by roof Jurassic sandstone water damage.In the past three years,the mining of the mine has gradually entered the area with a large buried depth,showing that the roof Yan’an Formation aquifer and Zhiluo Formation aquifer have relatively good water richness and large water filling intensity.In the 110504 working face recently excavated,the water abundance of the roof is significantly larger than that of the previous working face.The roof aquifer is fully recharged by the runoff of the surrounding high aquifer,and there is a certain head pressure.During the mining period of the working face,the threat of roof water damage is great,especially when the working face is first mined and first drained,the roof collapse will inevitably cause roof water inflow and affect the safe production of the mine.Based on the analysis of the hydrogeological conditions in the study area,this thesis studies the hydrogeological characteristics of the unconfined aquifer of the coal seam roof in the study area by carrying out underground dewatering test,underground geophysical exploration and construction of underground water exploration and drainage boreholes.On this basis,taking 110504 working face as an example,numerical simulation and theoretical calculation are used to study the prediction of water inflow in unconfined aquifer.The research results of this thesis are as follows:(1)In the study area,the maximum development height of the roof water-conducting fracture zone is 246 m when 5 coal is mined.The Yan’an Formation aquifer and Zhiluo Formation aquifer above 5 coal are the main water-filling sources of the roof during mining.Due to the large difference between the previous exploration results of Yan’an Formation aquifer above 5 coal and Zhiluo Formation aquifer and the actual exposed conditions in the underground,in order to realize the safe mining of the working face,the underground dewatering test,geophysical exploration and construction of underground water exploration and drainage boreholes were used to further explore the hydrogeological conditions in the study area.(2)According to the results of hydrogeological exploration,the hydrogeological characteristics of No.5 roof aquifer are studied:1)The water level of Yan’an Formation above 5 coal and the water level of the aquifer in the lower section of Zhiluo Formation are all below the relative aquifuge,which are unconfined aquifers,and the aquifer in the upper section of Zhiluo Formation is not rich in water.2)Based on the data of underground dewatering test,the hydrogeological parameters of Yan’an Formation aquifer above 5 coal,lower Zhiluo Formation aquifer and mixed Yan’an above 5 coal-Zhiluo lower Formation aquifer are solved respectively,and the unit water inflow of aquifer is solved.3)The aquifer of Yan’an Formation above 5 coal is closely related to the aquifer of lower Zhiluo Formation,and the degree of surface recharge is weak.4)When the underground water exploration and drainage borehole is used to drain the aquifer of Yan’an Formation above 5 coal and the lower aquifer of Zhiluo Formation,the water volume and water pressure decrease obviously in the early stage,and then gradually slow down,and the overall drainage effect is good.(3)Based on the research results of hydrogeological characteristics of unconfined aquifer,the groundwater numerical model of unconfined aquifer in the study area is established.The model is identified and verified by using the water level data of long observation hole and the intelligent monitoring data of water pressure in dewatering test.The results show that the numerical model conforms to the actual hydrogeological characteristics of the study area.The model is used to predict the water inflow of110504 working face.(4)Based on the water inflow mode of the direct water-filled aquifer of the coal seam roof,the water inflow model of’dynamic recharge water inflow+static storage release water inflow’of the unconfined aquifer of 5 coal roof is established.The modified’catchment corridor method’is used to calculate the dynamic recharge water inflow of the aquifer,and the static storage release water inflow of the aquifer is calculated in combination with the static storage and static storage drainage time of the roof aquifer,and then the water inflow of the working face is obtained.The theoretical calculation method of water inflow in working face is compared with the predicted results of numerical simulation.The results show that the predicted results of water inflow by the two methods are in good agreement,the water inflow increases gradually after mining,and the maximum water inflow is 371m~3/h.The established theoretical calculation method of water inflow is used to predict the 110105 working face of adjacent Yindonggou Coal Mine.The error between the calculated results and the measured water inflow is small,indicating that the theoretical calculation method is reasonable.The research results of this thesis can provide the basis of water prevention and control for 110504 working face,and provide reference for the mining of subsequent working face and similar working face in other mines.This thesis has 66 figures,28 tables and 79 references. |
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