Study On The Law Of Fracture Evolution And The Permeability Analysis In Overlying Strata Influenced By Mining

Along with the coal mining depth and mining intensity increasing, and the caving method of roof-controlmethods gradually populairzing, coal production is increasing, at the same time,the threat of gas is alsogradually increasing.The controlling of coal mine surrounding rock and high eiffciency and safe production arefacing the severe test.On the basis of the rock crack evolution and gas drainage engineering studies at home and abroad,basedon coal Mining science, coal mine gas prevention and control theory and engineering application, seepagetheory and numerical simulation,some explorations were carired out:①Descirbed the overburden crackevolution qualitatively and quantitatively. Through counting fixed area angle numbers,overlying rockmining-affected is divided into four areas.And the crack evolution is descirbed with crack area and the fractalvalue of crack number in the four areas.②According to the similarity simulation seepage data,it is concludedthat the high angle transition zone is the high permeability and high conduction area,and is the key area toimplement surrounding rock gas treatment project.?Through the research of overburden rock by the mininginlfuence,a relationship between stress and seepage is concluded： permeability can be expressed by theexponential function of vertical stress. Through the similarity simulation experiment,it is qualitatively“concluded that there is an rched b"eam permeability lower area in the middle of the stope to the highs.④Using numerical simulation,it is concluded that coal and rock mass layered storage is a major factor causingpermeability change.