Evaluation of spatial water enrichment of ultra-thick bedrockaquifer in coal seam roof

The aquifer of the coal seam roof in the Jurassic coalfield is highly heterogeneous in western China and has large differences in water richness. When the depth of the water-conducting fissure zone affects the aquifer is different, the amount of water inflow from the working face is different, and the threat of water damage is different.In order to scientifically describe the difference in the water inrush of the mine due to the difference of the vertical water yield property of the aquifer, the aquifer is simplified into a multi-layered structure, and an expression model for the spatial water rich structure of the aquifer is generalized. Taking Luohe Formation aquifer in the coal seam roof of the Tingnan coal mine in Binchang mining area as an example, the three main controlling factors affecting the water yield property of the aquifer were proposed: aquifer system, flow system and geological structure, the seven main controlling factors of aquifer thickness, flushing fluid consumption, core extraction rate, proportion of medium-coarse sandstone, stratum burial depth, water chemical salinity, and fold structure were determined, and the weights of each factor were determined by AHP analytic method. Finally, a mathematical model for evaluating the water-rich aquifer is formed.In this paper, the information of the main control factors of different vertical horizons is unified to normalized, using the multi-source information fusion technology to superimpose and establish a water yield property evaluation model for aquifer.The evaluation results show that the upper section of Luohe Formation aquifer can be divided into 3 zones: strong, relatively strong, and medium, and the lower sectioncan be divided into 5 zones: strong, relatively strong, medium, relatively weak, and weak. The comparison shows that the upper section has better water richness than the lower section, and it is verified by fitting the results through the pumping tests of aquifers in different intervals JP3within the range of the well field.It can be concluded that the model can fully reflect the difference of water yield property of different spatial positions (horizontal and vertical) of the aquifer, and it can guide the evaluation of the water hazard risk of the roof under the condition that the water-flowing fractured zone only affects the partial layer of the aquifer.