Development on basic theory of water protection during coal mining in northwest of China

In terms of the key scientific problems in the research of basic theory on water resources protection during mining on coal seam in northwest China,this paper introduces the following research developments:the stratigraphic structural characteristics of northwest coalfield,the space-time evolution laws on the stabilities of the overlying strata structure and aquiclude,and the mechanism and control theory of water-protection coal mining. The geometrical struc- ture model of ecology-water-coal measure rock strata was established based on different eco-geological types in north- west mining area. Distribution characteristics and water cycle migration regularity of the shallow water resources were analyzed. The expression and reconstruction method of overlying rock fracture was proposed. The coordinated variation model and the gradual variation model on the relationship among upper aquiclude,medium barrier strata and lower main roof were built. A classification system on water-protection mining technology referred to virginal / repeated mining was constructed. A new type of shortwall mining with water protection was explored. The above works lay a foundation for scientific coal mining method on water protection in northwest of China.