Research on roof control of water conservation mining in shallow seam

The core idea of the shallow buried coal seams in Western China is to protect the ecological water level. The theoretical basis of the strata control in water conservation mining is the stability of the water resisting layer. According to simulation model tests and mining surface cracks observation,it reveals that the cracks of overburden strata induced by mining are mainly composed of “upwards cracks” and “downward cracks”. The water resisting property of overbur- den aquifer layer depends on the interpenetration of mining cracks band. The calculation formulas of the height of up- ward crack zone and the developing depth of downward crack zone are set up. Based on the thickness of the water re- sisting strata to the mining height,so-called resisting-mining thickness ratio,the water resisting criterion is established, and the classification method of water conservation mining is also put forward. Based on the overburden condition of Yushenfu mining area,the classification index range for the water conservation mining in shallow buried coal seam is suggested.