A Study On Coupling Effect Between Rock And Water In Coal Floor And Safety Mining Technology Under High Groundwater Pressure

Groundwater inrush into coal mines from coal floor is one of main types of water hazards threatening coal safety in China. Specially, this threatening is more and more severe with the increase of mining depth. To the theoretic and technologic problems in mine groundwater control, the author chose the thesis title as "Study on Coupling Effect of Rock and Groundwater in Coal Floor and Safety Mining Technology above confined aquifer with high groundwater pressure", which is of great theoretical meaning and application value.After a comprehensive and systematic analysis of the state of the art and developing trend on the study of water inrush from coal floor both domestic and abroad, aimed at some key scientific and technologic problems in related research areas, through theory study, lab experiments, site tests and numerical modeling, the thesis analyzed factors related to groundwater inrush from coal floor, rock mass stress and strain distribution characteristics during mining and rules of mining breakage to coal floor, dissertated the coupling mechanism of groundwater flow and rock mass stress; set up the theoretic formulas between groundwater flow and rock mass stress, studied the coupling mechanism between stress field and flow field in different scale before and during mining; systematically studied water deterioration to rock, gained experiment relations between rock mechanic indexes and water saturation, and achieved a conclusion that water deterioration to rock reaches maximum when saturation is around 30%, this is one of creative points of this dissertation; by centrifuge modeling, the dissertation studied the relations of wall rock breakage with opening width, rock strength and wall rock thickness, and obtained the rules of wall rock breakage and distortion with different opening width, different stress acceleration and different wall rock thickness. Centrifudge modeling provides a new method to study mining damage to wall rock under different stress conditons, and this pilot research is another creative points of the dissertation . Applying Water Inrush Index and mining under groundwater pressure theory, the dissertation conducted mining zoning in respected to mining under groundwater pressure in Zhongsan mine, Feicheng coal field, determined lower mining limit. FLAC 3D was used to simulate stress and strain distribution rule, rational ratio of mining and reserve width was given, and finally safety mining technique and methods with thin protective aquiclude and high groundwater pressure and corresponding groundwater control measures were proposed.