Research Of The Effects On Outburst Elimination Of The Hydraulic Flushing In Xin'an Coalfield

Xin'an coalfield is typical of"three soft"coal seam structure,and is famous for high Coalbed gas content,usually in the 10m3/t to 13m3/t, the maximum numeric up to 26.22m3/t. Xin'an coalfield has a poor condition in mining covering layer,due to the special coal bed storage,it has a problem in construction and the control effect for coal and gas outburst to adopt conventional measures of Pre-drainage of coal-bed methane:it is difficult to construction hole,and easy to induce coal and gas outburst;it is because of low gas permeability coefficien and rheological character that it is easy to produce slumping of hole,influence drainage effect;The drainage radius of influence is small,and that decides more holes.It is crossing hole hydraulic flushing technology that avoids these problems above.It adopts rock gangway as safety barrier pillar,uses high pressure water jet,out of a certain number of coal and emit partial gas,makes coal gas release potential;what's more,it can enhance seam shrinkage deformation,the stress decreased,increases gas permeability according to drainage after flushing,finally reachs the purpose of eliminating coal and gas outburst.Papers reviewed and fixed punching process and technical standards adaptation to"three soft"coal seam of xin'an coal field by ways of tests in Xin'an and Yian coal mine.It fixed that the crtitical effective pressure of punching.is equal to between 13f and 16f.the nozzle model adopted is 2*Φ5mm.and the punching order is from outside to inside,the emphasis is setted at common border of coal rock.According to numerical imitation of stress distributed after punching,we get a conclusion that it can avoid stress focusing when distance between adjacent two points of crossing coal is 8m, on the precondition of a standard of no less than 5t haplopore and 1t per s coal hole.These optimize to the hole arranging.To aim at the otherness in ocurrence of gas of test point of Yian coal mine,papers made a division of gas geology unit.It can work out its own specially adapted punching measures,and this can increase the anti-conflict effects with effect.By way of effect research and evaluation,papers get a conclusion that the face will get a good improving permeability and relieving pressure when the coal punched can reach to make up 1% of the total of controlled range,and that give a big previous guide to punching job,also get a conclusion that proportion of the coal punched can replace expansion deformation as evaluation index of outburst elimination.What 's more,these give a help to correct and sound the punching process and the technical standard system,Better to improve their anti-conflict effects.test results approve that hydraulic punching technology is suitable to Xin'an coal bed storage features,avoid the problem and shortcoming conventional pre-drainage,not only can cancel face 's dange quickly,tunneling speed is also increased by 100%,reach the safe and fast requirements of tunneling.