The proposed technology allows increasing of pit slope an-gles and minimizes the overburden operations; at the same time, over a twofold decrease in the intensity of damage of the peripheral rock mass is observed; the quality of rock crashing mass improves 1.5 times; and the oversize outcrop is reduced. The technology is based on the geotechnical bench designs offering arrangements of benches in the limiting position and original patterns of multiple row short-delay blasting.
The interval of short-delay time, milliseconds | Bench marks shift (mm) at the distance from the last hole row (m) | Rock mass crushing quality (according to oversize outcrop), % | |||
In the first raw of holes | between the adjacent holes in rows | 13.3-16.6 | 18.8-22.4 | 23.5-27.2 | |
42 | 42 | 293 | 154 | 29 | 2.54 |
100 | 42 | 104 | 92 | 72 | 1.81 |
100 | 67 | 82 | 36 | 14 | 1.65 |
The proposed technology is featured with optimized bench heights and inclination angles, taking into account the physical-mechanical and structural properties of the rock mass. The technology offers the alternation of narrow and wide berms, which results in the working benches to be formed on the limiting contour into high benches of a staggered form.
Optimized order of firing in the explosion block based on the developed design procedure on shortdelay intervals between the hole charges in the first row and between the rows of hole charges makes ensures independent performance of each of the charges and makes it possible to control the direction of the rock mass breaking frontline.