The Stress Concentration Belt Distribution Research Of Soft Coal Seam In Front Of Mining Face

The main reason for low rate of our gas extraction is that many highlygassy or outburst coal seam is soft coal and of low permeability. The key to solve the extraction rate question is to increase the permeability of coal seam."Discharging pressure and increasing permeability " is an effective way to improve permeability of soft coal seam whose permeability is very sensitive to the stress.Influenced by mining, the coal seam stress originally in balance distributes again, resulting in the stress discharging and concentration zones in front of the mining face.the permeability of discharging zone increases for the stress is discharged and provides convenient to gas drainage but the range is rather small. However, Within the stress-concentration zone, the permeability becomes lower as a result of stress increasing and the gas extraction difficulty increases.The highlygassy zone is inclined to coal and gas outburst which threats badly the production safety. Low permeability in soft coal seam mining face, clear the stress-concentration zone, front roof-floor belt distribution features, is to adopt effective increase through technology improve the baggage hold pressure gas extraction rate is the basis and important reference.. As for the soft coal seam of low permeability, definiting the distribution features of stress concentration and discharging zone in front of mining face, is the basis and important reference to improve gas extraction rate by means of adopting effective "discharging pressure and increasing permeability " technology.In this paper,the preliminary distribution characteristics of the stress-concentration zone ahead of mining face in soft coal seam.Is got by way of establishing vertical stress numerical mode of mining coal mining in front of mining face as well as calculating and analysising the distribution characteristics of the stress-concentration zone ahead of mining face in soft coal seam whose .sturdiness coefficient (f) is smaller than 0.5. Numerical simulation results coincide with experimental data by contrasting and validating whit practical measurement datas of face 31091 in XinDeng coalmine which shows the rationality and reliability of the numerical model and it,s simulation results ahead of mining face in hard coal seam. Then calculate and analysis similar hard coal seame whose sturdiness coefficient (f) is bigger than 0.5 and get the distribution characteristics of the stress-concentration zone ahead of mining face in hard coal seam. confirmed a soft coal seam mining coal gateways ahead the stress-concentration zone regularity of distribution. Basing on comprehensive comparison and analysis of the difference between the result of two types of coal, get finally the distribution regularity of stress-concentration zone ahead of mining face in coal seam.