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.
Highlights
Blasting is generally the initial stage of rock breakage in mines, quarries, or geotechnical constructions, and its outcome plays a strong role in all downstream operations, such as loading, hauling, and crushing [1,2,3,4]
The mathematics and mechanics analysis and the experimental results both indicate that the detonator location plays an important role in the distribution of explosion energy and blast stress field
For the top detonator case, the damage preferentially develops to the hole bottom, so the damage profile looks like an inverted funnel (see Figure 17(a)). e downwards transmitting explosion energy under top detonator location is beneficial to the rock fragmentation at the hole bottom, but weakens the rock breakage at the top zone, Figure 16: Numerical model of the multihole blasting
Summary
Blasting is generally the initial stage of rock breakage in mines, quarries, or geotechnical constructions, and its outcome plays a strong role in all downstream operations, such as loading, hauling, and crushing [1,2,3,4]. E previous studies related to the detonator location mainly focused on the rock fragmentation and blast stress field. Liu et al [17] studied the effect of detonator location on boulders and rock toes in bench blasting via the numerical simulation and blasting practice. By considering the acting time of gaseous products, most previous researchers recommended the bottom detonator location [14] They ignored the effect of detonator location on the spatial distribution of explosion energy transmitted into the surrounding rock mass. The effect of detonator location was analyzed both mathematically and mechanically from the point of the distribution of explosion energy and blast stress field of a cylindrical charge. Location was proposed based on the idea of combining the merits of top and bottom detonator locations. is study is of interest to improve the efficiency and profit in mining
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