Numerical Study on an Innovative Shaped Charge Approach of Rock Blasting and the Timing Sequence Effect in Microsecond Magnitude

Directional fracture controlled blasting technology plays a significant role in rock blasting engineering, in which the shaped charge forms are usually utilized. The energy-gathering form of shaped blasting still has no unified and strict standard currently, which can be optimized to save charge materials and improve blasting efficiency by a further study. In this paper, the breaking mechanism of rock blasting using the general cylindrical Bilateral-Groove (the groove is in “V” shape) Shaped Charge (BGSC) approach was analyzed theoretically. Several cases with different energy-gathering forms using rock drilling and blasting method were tested by numerical modeling, and then an innovative approach of BGSC was determined through comprehensive comparative analyses. It was found that the optimal blasting effect, which has the longest directional cracks, few non-directional cracks and light damage to the surrounding rock, can be achieved by decoupling Bilateral–Groove-Slot Shaped Charge (BGSSC) blasting. Then the decoupling BGSSC approach was adopted to study the timing sequence effect in microsecond magnitude for double-borehole rock blasting. The results of the numerical tests indicated that acceptable blasting effect with a good through crack and less damage in surrounding rock could be captured when the delay time is located in 0–40 μs and 600–800 μs, which have a consistent changing tendency of the effective stress and lower oscillation range than the other delay schemes. This study can provide important theoretical bases for the development of blasting engineering technology on the aspects of shaped charge form and short time delay blasting scheme.