The analysis on presplitting blasting to improve permeability draining rate in heading excavation
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Abstract:
Aiming at the problem of low excavation speed and high risk of coal and gas outburst because of low gas draining rate in heading excavation,and taking an excavation heading of a mine for example,the test of deephole presplitting blasting is processed.The amount of gas draining after presplitting is compared with the amount of direct draining,and the effective radius of draining is surveyed.The test result shows that the draining rate of K1 coal seam reaches 37.13 %,which reduces the draining time by 60%,10 days after presplitting,and the gas desorption index exceeds the standards until the fifth blasting.The draining rate of K4 needs 12 days to reach 34.28 %,which reduces the draining time by 60%,and the gas desorption index exceeds the standards when the third blasting processes.Obviously,the effect of gas draining is improved by presplitting blasting.The effective draining radius of K1 and K4 are 4.5 and 5.2 m respectively after presplitting blasting.The research can provide reference for the fieldwork of presplitting blasting.
