Numerical simulation on parameters optimization of deep-hole pre-splitting blasting of hard roof

Deep-hole pre-splitting blasting is an effective way to weaken the hard roof, but the selection of pre-splitting blasting parameters has a great influence on the roof weakening effect.A fully mechanized top coal caving face with hard roof in 22205 thick coal seam of a coal mine in Shanxi province is selected the specific research background.An equivalent continuous mechanical parameters estimation method of rock mass after pre-splitting blasting is proposed based on Hoek-Brown strength criterion, and a three-dimensional numerical model of deep-hole pre-splitting blasting of hard roof is established by using FLAC^3D software.The effects of key parameters such as the distance between the blasting hole and the cutting hole and the depth of the blasting hole on the first roof weighting interval of the hard roof are studied.On this basis, the deep-hole pre-splitting blasting schemes and parameters of the hard roof of 22205 fully mechanized top-coal caving face are reasonably proposed and optimized, and the field engineering practice is carried out.The in-site mine pressure monitoring results showed that after adopting the deep-hole pre-splitting blasting technology, the first roof weighting interval of the hard roof is reduced by about 20 m, which significantly improves the safety condition during the hard roof pressure and ensures the normal and safe production of the working face.