Cas Control Technology With Deep Hole Pre-splitting Blasting Controlled Caving On1123(1) Working Face In Guqiao Coalmine

Hard roof problem has been a big factor in coal mine safety production. As the high strength of hard roof, the crack is not development. It is easy to form large overhang and accumulate a large amount of gas when the coal was mining. When large areas of suspension of the roof collapse suddenly, the strong storm with high levels of gas spewing out, it is not only destory roadway of support equipment but also cause a series of gas outburst and explosion accidents to personnel and immeasurable loss. This paper is on the background of guqiao coalmine, in view of the hard roof thickness is big of1123(1) working face may cause large overhang and the suspension of the roof reduces the effect of bottom plate extraction roadway in1123(3) working face. So, the paper may use the theoretical research, numerical simulation, field test methods for deep hole pre-splitting blasting forced caving to weaken the hard roof, in order to improve the efficiency of gas extraction and provide security for1123(1) working face smooth recovery.This article through the discussion of hard roof in fully mechanized face strata mechanics model and the moving rule, calculating the first caving step distance of51.8m in1123(1) working face. On the base of hard roof softening method analysis and study of blasting crack law of development, it is concluded that the1123(1) can use the deep hole pre-splitting blasting to weaken the hard roof. By using numerical simulation discrete element software state UDEC known that the first caving step distance is48m before caving roof and the first caving step distance shortened to20m after deep hole pre-splitting blasting to cut off the roof, so the deep hole pre-splitting blasting caving effect is apparent, it is can carry out field test. By the site after blasting caving mine pressure monitoring data, the six extension basic are about27.3m in the low pressure, it is clear that the roof caving at27.3m. By the site after deep hole pre-splitting blasting gas extraction data shows that it is mainly on bedding and wind to control the gas hole before the roof pressure relief. The bottom plate extraction amount in50m3/min and the gas extraction concentration at around30%after the roof pressure relief. Absolute gas emission began to increase at the distance of33m of the cut. Because of the deep hole pre-splitting blasting the roof caving in advance to make the roof pressure relief, the amount and concentration of gas are greatly increased.