부산대학교 도서관

Nowadays, the blasting volume and the corresponding explosive demand have been increasing more and more with the continuous growth of open-pit mining projects. There is a substantial waste of explosive energy due to fly-rock and vibration in the blasting process. In order to maximize the utilization of explosive energy, the air-deck stemming structure is generally adopted. However, punching mechanism of the air-deck stemming structure is not revealed yet. In this study, the solution equation of punching height is first obtained to theoretically analyze the movement mechanism of blasthole stemming. Then, the effects of different stemming structures (air-deck stemming and conventional stemming) on the punch height and rock fragmentation are investigated by conducting three field experiments. Finally, the meshless smoothed particle hydrodynamics (SPH) model in ANSYS/AUTODYN module is employed to analyze the velocity of the stemming, the blasting pressure near the hole wall, and the rock fragmentation. The results show that: (1) compared with the conventional stemming structure, the air-deck stemming structure reduces the average punching height by 48–66%, which can mitigate the environmental hazards due to the blasting dust. (2) The size of the rock fragments in the conventional stemming area is significantly higher than the ones in the air-deck stemming area. The volume of the rock fragments with sizes smaller than 100 mm is 60–81% in the air-deck stemming area but only 24–45% in the conventional stemming area. (3) Compared with the conventional stemming, the blasting pressure increases by 1–2 times at the stemming part and decreases by 1.25–2 times at the charging part by using the air-deck stemming. The results show that the explosive energy can be effectively utilized by using the air-deck stemming structure, which provides significant guidance for the drilling blasting in the increasing open-pit mining projects. Highlights: The solution equation of punching height can be deduced by Newton's law of inertia and the conservation of momentum principle through theoretical analysis. Three field experiments are conducted to study the effects of air-deck stemming and conventional stemming on the punching height and the rock fragmentation. The stemming velocity, the blasting pressure, and the rock fragmentation are analyzed using the meshless SPH model in AUTODYN module. [ABSTRACT FROM AUTHOR]