The Application On The Effect Of Mining Height And Key Layer In Rock Mining Fissure Evolutionary

The pre-degasification effect is less in China, because most of coal-bed methane existing"three high-low" features. It is an important tackling methane direction that using movinginfluence and mining-induced fracture evolution features of mining overburden rock to degas.The paper systematically summarized and reviewed plenty of achievements of rock stratamovement, it can get that the effection of mining height and the key layer on the evolution ofthe mining overburden rock fissure, which are the study key points for the paper.By the means of physical analog simulation experiment, observing the overburdensubsidence, fracture density, maximum quantity of abscission layer, the hulking coefficient,fracture height and caving height, to research the effect of mining height and the key layer onthe evolution of the mining overburden rock fissure. The research results show that it issimilar on the mining strata movement, fracture development, evolution characteristics underdifferent mining height and different key layer, it fo rm a mining fissure zone in the miningoverburden strata, as the working face continue promoting, the influence range continuousexpanding, along the working face advancing, crack evolution is characterized by three phasecharacteristic; under the different mining height, with the increasing of mining height,overburden subsidence, fracture density, the largest amount of abscission layer, the hulkingcoefficient, fracture height and caving height increases; under the different the key layer, withthe increasing of K2from coal seam roof key stratum, the overburden subsidence, fracturedensity, the largest amount of abscission layer, the hulking coefficient, fracture height andcaving height increase.Through the study on the evolution of strata mining-induced fracture, Based on the effectof mining height and key layers on mining overburden rock fracture, by theoretical analysis, itis concluded the height of caving and determined the reasonable horizon high drainageroadway, it is applied to Tianchi301working face, assuring the safety and high effectiveproduct in301working face.