Drilling for detonations
is a technique most commonly used in mining, quarries, roads construction, tunneling and dams construction. The purpose is to induce fractures in the internal geology of the surrounding rock and facilitate further drilling or other related activity. After constructing numerous boreholes made into the surface of the rock, an explosive is placed, after which the rock is detonated. The result of rock blasting is often known as a rock cutting. The boreholes are spaced to require a minimum amount of explosive per volume of broken rock (called the dust factor). Most blasthole models are based on the fact that fragmentation is most uniform if the exploding charge is a certain distance from the exposed rock surface. To break up a large mass of rock, the charges are placed in a series of boreholes drilled so that when the holes are blasted, those nearest the exposed surface, their blasts create new exposed surfaces at the proper distances from the next series of boreholes, in which the detonation of the charges is slightly delayed. The boreholes are detonated in a predetermined order, at intervals of only thousandths of a second.