Abstract
Shaped charge blasting (SCB)—a directional fracture blasting technology—has the disadvantages of low safety, harmful gas, and dust emissions. This study proposes a new type of directional rock-breaking technology called shaped charge hydraulic blasting (SCHB) that uses water as the blasting medium instead of air. To verify the effectiveness of the new method, we performed a theoretical analysis. Twelve groups of on-site directional roof-cutting tests were carried out on SCB and SCHB for comparison in a coal mine. The results showed that, although both blasting methods achieved the goal of directional roof cutting for noncoal pillar mining, SCHB had greater blasting power and produced 8% higher crack rate than SCB for the same charge amount. SCHB required 12.5% less charge than SCB when the crack rate was basically the same. SCHB effectively reduced the concentration of CO. The maximum concentration of CO was reduced by 22–62% compared with SCB. The maximum concentration decreased parabolically with the monitoring distance. In addition, water can absorb high temperature and inhibit sparks from blasting, so SCHB can prevent gas explosions. Therefore, SCHB is an environmental, safe, and economical method of directional roof cutting, which has wide applications in mining and geotechnical engineering.
Highlights
Noncoal pillar mining does not need to manually or mechanically dig into the roadway
The cracks generated by Shaped charge blasting (SCB) and shaped charge hydraulic blasting (SCHB) after the blast are shown in Figures 11(a) and 11(b), respectively
This was because, whether it was SCB or SCHB, the orientation effect was achieved by the directional slit tube
Summary
Noncoal pillar mining does not need to manually or mechanically dig into the roadway. Directional rock-breaking methods include soundless chemical demolition agents, water jets, directional hydraulic fracturing, slot hydraulic blasting, and shaped charge blasting (SCB). The directional roof-cutting technology applied to noncoal pillar mining with roadway formed automatically is mainly SCB [11,12,13]. This method emits toxic and harmful gases [14, 15], large dust [16, 17], and other explosive substances. The technology can generate cracks in a directional way, reduce the amount of toxic gas, and save the explosive charge It is a green, safe, and economical method of directional rock breaking. The directional roof-cutting effect, crack rate, explosive dosage, and CO concentration of the two methods were compared
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
