Predictions Of Height Of Water Flowing Fractured Zone And Water Inflow Under Fully Mechanized Top-Coal Caving Of Shilawusu Coal Mine

With the gradual westward shift of China's coal mining strategy,Erdos energy base has become an important production base for coal development in recent years.The Shilawusu coal mine is located in the northern part of the Ordos Basin.It belongs to the typical deep mine.The thickness of the coal seam is large and the buried depth is deep.The thickness of roof aquifer is large,and the water content of sandstone fractured aquifer is not uniform.It seriously threatens the safety production at the working face.The surrounding mine has not been large-scale mining activities,and lack of mature experience for reference.Therefore,it is necessary to study the basic law of the deformation and failure of overlying rock and evaluate the risk of the roof water damage.The paper takes Shilawusu coal mine as the study area,based on previous research achievements of Jurassic deep coal seam mining,the geological and hydrogeological data of the study area were systematically collected,and the hydrogeological conditions and structural characteristics of the aquifer were analyzed.On the basis of collecting the measured value of the height of water flowing fractured zone with the similar condition of the Jurassic coal field,the development characteristics of the height of water flowing fractured zone are analyzed and the predicted formula suitable for the height of water flowing fractured zone in the study area is fitted,it is calculated that the height of water flowing fractured zone in the fully mechanized caving area is between 232-297 m.According to the geological conditions of the first mining face in the fully mechanized caving area,the dynamic characteristics of overburden failure are simulated by FLAC3 D software.The simulation results show that the height of water flowing fractured zone is about 240 m when the thickness of coal seam mining is 10 m.Research based on the height of water flowing fractured zone,the factors affecting the roof water damage in fully mechanized topcoal caving are analyzed,the thickness of direct water filled aquifer,the thickness of indirect water filled aquifer,the rate of core collection,the ratio of hard rock,and the thickness of the residual aquifers,and the analytic hierarchy process are applied to evaluate the risk degree of roof water hazard in the fully mechanized top-coal caving area.The water inflow of first mining face in fully mechanized caving area is 383 m3/h,based on the difference of the height of fully mechanized topcoal caving and fully mechanized mining.Considering the leakage of Zhidan group,the prediction value of the normal water inflow of the first working face is 575 m3/h.Due to the possibility of the existence of the separation water,the maximum water gushing amount is 2 times as much as 1150 m3/h of the normal water flow.Through the analysis of the actual water inflow during the mining period,the prediction value of the water gushing amount is basically consistent with the actual situation.The research results will promote the development of safe and efficient green mining technology in Dongsheng coalfield,and provide guidance and reference for the safe mining of the thick sandstone aquifer,which has important theoretical and practical value.