Theoretical analysis and Numerical Simulation Study on failure depth of coal seams floor caused by mining under pressure

With mining depth increased, most coal mine will face high pressure groundwater threat. Bearing mining has already became a coal mining method universally employed in deep mine of China, one of key problems in coal mining above confined aquifer is how to determine the depth of destroyed floor due to mining influence, but the conventional method of mining failure depth from coal seam floor in coal mining above confined aquifer possesses high cost and study cycle long and other shortcomings. In the paper, taking mining No.5 Coal Seam of Cheng-He Mining Area as an example,this paper analyzes a method which combines the numerical simulation with theoretical calculation is brought forward, while the testing data are compared with those from the in situ measurement, drawing detailed reliable actual information can ensure safety in mining, it can be dynamically reproduced that the development and failure process of the whole floor strata during mining advance.The numerical simulation results educes the 12~13m failure depth of the coal seam floor of mining working face, meanwhile, the results may be used to guide practice with similar water prevention work of a working face of bearing mining and design of the water control method, and also provide scientific basis.