The dynamic effect of shaped charge blasting and its
application
in coal seam permeability enhancement have been investigated. Comparative
experiments of shaped charge blasting and conventional blasting to
fracture the concrete are carried out. Then, the propagation characteristics
of explosion stress waves under shaped charge blasting and conventional
blasting are analyzed by ANSYS/LS-DYNA. Finally, the fracture mechanical
model of shaped charge blasting is established. The experimental results
show that the width of the four main cracks formed after conventional
blasting is 0.3 cm, while the width of the cracks in the energy accumulation
direction after shaped charge blasting is 1.1 cm and the width of
that in the vertical energy accumulation direction is 0.4 cm. The
numerical simulation results show that the crushing area after shaped
charge blasting is “dumbbell type”, and the area is
smaller than that of conventional blasting. However, the cracking
area is “spindle type”, and the development of the fracture
degree is better than that of conventional blasting. In addition,
shaped charge blasting is used to improve the permeability of coal
seams. The results show that shaped charge blasting effectively improves
the permeability and gas extraction rate of coal seams.