Study On The Development Law And Hydrogeological Effection Of The Water Flowing Fractured Zone In The Western Jurassic Strata

In recent years,the focus of China's coal mining has gradually shifted to the west.The main coal-bearing strata in the western mining area are the Xishanyao Formation of the Jurassic Middle System.Because of its special diagenesis geological environment,the coal-bearing strata have the characteristics of late diagenesis,low physical strength,easy weathering and cement disintegration.There are obvious differences between the eastern Carboniferous and Permian system,and the characteristics of water flowing fractured zone are unique.By taking the Dananhu mining area as an example,the development law and the hydrogeological effection of water flowing fractured zone are studied on the basis of a systematic study of the structure,cementation characteristics and aquifer-aquifuge structure.The main achievements in this thesis are as follows:?1?Through the physical mechanics parameter test,scanning electron microscope and related theoretical research,the results show that the Jurassic coal-bearing strata in the study area has the typical weak cementation characteristics,such as low mechanical strength,poor cementation degree?particle contact cementation?,high porosity and loose structure;through the comparison of borehole data,actual disclosure and hydrogeological exploration,the results reveal the aquifer in the roof of main coal seam has the segmental characteristics.?2?Studying the law of development of water flowing fractured zone of the Jurassic coal-bearing strata in western mining by similar material simulation and FLAC^3Dnumerical simulation.Simulation results show that:In terms of the development height,the water flowing fractured zone develops to the bottom of the16 coal aquifuge,and the final height is stable at 46⁴7m.The ratio of the height of caving and fractured zone to the mining height are 3.33 and 15.33¹5.67,The simulation results are close to the measured results by the empirical formula calculation,the comparison of the measured results of the adjacent and the similar strata mine.In terms of the development form,the range of development of the water flowing fractured zone shows the basic characteristics of"ladder"type because of the special rock structural conditions in study area.?3?Revealing the hydrogeological effection of the water flowing fractured zone in study area under the special strati-graphic structure:The water flowing fractured zone forms the water channel,which destroys the structure of the lower aquifer of?-1 and increases the permeability of aquifer;The water level of the aquifer is decreased,and the permeability coefficient is increased from 0.88m/d to2.6⁴.1m/d.Due to the existence of the 16 coal aquifuge,the further development of the water flowing fractured zone is effectively controlled,and it is avoided to reach the strong rich water of the upper aquifer of III-1.The study of this thesis on the height,range of influence and hydrogeological effection of the water flowing fractured zone under the special hydrogeological structure of the Jurassic strata in the western mining area has certain theoretical and practical value for the prevention and control of the roof of mine water disaster.