Law of mining induced water conduction fissure in arid mining area and its significance in water-preserved coal mining

With the focus on the gradual westward shifting of coal resources development in China,the western region has become the main production areas. In general,the ecological environment is relatively weak due to the low precipi-tation and high evaporation. Taking the Dananhumining area in Hami coalfield,Xinjiang,as an example,in view of the late diagenesis time,low physical intensity and easily muddy disintegration of Jurassic coal-rich strata in this area,sim-ilar material simulation and numerical simulation are used. Based on the field observation and comparison of the neigh-boring coalmines,several significant rules are studied including the development and evolution process,the develop-ment height and morphological characteristics,the permeability evolution law in roof water flowing fractured zone and the water protection during coal mining (water-preserved mining). The results shows that in the Jurassic coal-rich stra-ta,the development ratio of water flowing fractured fissure is generally between 13. 09 and 15. 67,and the overall morphology is characterized by “terrace-type”. Fracture and permeability coefficient evolution in the range of mining im-pacts reflect the characteristics of “ stable increase-fluctuation-recovery stability”,and the permeability coefficient of aquifer increases obviously reaching 3-5 times within the influence range of the height of water flowing fractured zone. The main coal seam roof in the study area has the “high aquifuge under multi-aquifer structure” structural characteris-tics,which possess the basic hydro-geological preconditions for water retention. Combined with the protection seam’ stability,the upper aquifer of iii-1 static reserves,the development potential and the comprehensive evaluation of the water-preserved mining feasibility in the research area,and the significance of water protection during coal mining in arid mining area are discussed.