Application of Roof Pre-cracking Technology in Gas Control in Initial Mining Stage on Working Face

The hard roof caved in extensively of a coal mine with a high content of gas will cause a large quantity of gas to gush out suddenly, it will inevitably lead to gas accumulation in the upper corner of the working face and gas content over limit in the return air flow. In order to study the effect of roof pre-cracking technology on gas control in the initial mining stage on working face, taking S5202 fully mechanized working face of Yuwu Coal Industry as the background, analyze the reasons of gas accumulation and gas content over limit in the upper corner caused by the hard roof caved in extensively, the layout of blasting hole and blasting time and mode were optimized, after the implementation of roof pre-cracking technology, the trend and dip pressure distribution curves of the working face were drawn. The results show that after the roof pre-cracking, the hard roof will collapse as soon as possible to form a caving crack, the mining and pre-split cracks will connect the high drainage roadway in time. In the process of working face advance, the pressure relief gas of this coal seam and adjacent strata is drained by the high drainage roadway, gas emission is greatly reduced in the initial mining stage, and gas control effect is obvious. There is no gas accumulation in the upper corner or gas content over limit in the return air flow.