Progress of water-preserved coal mining under water in China

According to the theories and practices in water-preserved coal mining under water in China，research progress on the evolution law of mining-induced water conducted zone in overburden and on the basis of which the water-preserved mining countermeasures or solutions formatted has been summarized in the paper，as well as the outlooks.The research indicate that the destruction of the underground aquifer and groundwater loss have are rooted in the mining-induced fracture.The dynamic development of the fracture is controlled by the breaking movement of the key strata (KS).In this aspect，the height of the water-flowing fractured zone can be determined by the occurrence of KS in overburden under the specific mining condition.Accordingly，the water-preserved mining methods can be draw up scientifically.In terms of the four levels of connotation，the progress of water-preserved mining technology has been summarized in four aspects: prevention of water inrush disaster in roof，in-situ protection of underground aquifer，regeneration of the mining-destroyed aquifer，and the storage of the mining-lost groundwater and its recycle utilization.Based on the above，three main projects that should be studied in future have been summarized.