Mathematical and Mechanical Analysis of the Effect of Detonator Location and Its Improvement in Bench Blasting

Abstract

The outcome of bench blasting significantly affects the downstream operations in mining. In bench blasting, the explosives charged in blastholes are generally cylindrically shaped and fired by the in-hole detonator. As the detonator determines the propagation of the detonation wave in the cylindrical charge, the effect of detonator location can never be ignored. In this paper, the mathematics and mechanics of the effect of detonator location was analyzed from the view of the distribution of explosion energy and blast stress field of a cylindrical charge. Then, a field blasting experiment and two numerical simulations were conducted to further display its effect on blasting outcomes. At last, the appearance of oversize boulders and rock toes in bench blasting was discussed, and an improved scheme of the detonator location was proposed to cope with these problems. Results indicate that the in-hole detonator has the capacity of adjusting the spatial distribution of explosion energy and blast stress field in the surrounding rock mass. The traditional recommendation of the bottom detonator is not always right. The optimized detonator location in bench blasting is available by properly combining the merits of traditional detonator locations. This study is of interest to improve the efficiency and reduce the cost of mining.

Reduction of Fragment Size from Mining to Mineral Processing: A Review

“…Stress wave analysis has demonstrated that if each hole has only one detonator, the best detonator position in sublevel caving rings and bench rounds is the midpoint of the explosive charge length (Zhang 2005a(Zhang , 2016aYlitalo et al 2021). Numerical simulation (Long et al 2012;Menacer et al 2015;Liu et al 2015) and mathematical analysis (Gao et al 2020) yield the same result as the stress wave analysis. Similarly, stress wave and shock wave analysis has shown that for long holes with two detonators, there is an optimum location for them (Zhang 2014).…”

Blasting Vibration Characteristics Calculation Formula considering Cylindrical Charge Delay Time

“…A comparison was conducted on the blasting vibration fields of the cylindrical charge at different initiation positions. Gao et al [30] analyzed the mathematical and mechanical laws of detonator position effects from the perspectives of the explosion energy distribution and the explosion stress field of the cylindrical charge. Based on the spherical cavity source model, Xu and Qi [31] used the superposition method to calculate the seismic wavefield excited by the horizontally distributed charge and revealed the amplitude and frequency characteristics of seismic wave excited by horizontally distributed explosive.…”