On the destruction of rocks during shot drilling

Abstract

Shot drilling is a mechanical method of breaking rocks. Unlike other methods of core drilling, it is characterized by the fact that the material that breaks the rock - shot - is not attached to the crown, but is freely located on the bottom of the well and can be continuously replenished during the drilling process. With the simultaneous action of the rotary motion of the crown and some pressure transmitted by the crown to the bottom, the shot located in the well is set in motion, resulting in the deepening of the well. The force transmitted by the shot to the rock, in places of contact of the shot with the rock causes stresses, the value of which, in order to ensure the destruction of the rock, must be no less than its tensile strength. Under these stresses, violations of the integrity of the monolith in the contact zone with the shot appear, as a result of which the separation of rock particles occurs. In turn, the shot must have sufficiently high mechanical qualities. The minimum consumption of shot must ensure effective destruction of the rock. The efficiency of drilling is largely determined by the quality of the metal of the drill bit. A certain correspondence between the mechanical properties of the crown and the shot is necessary. There is still no single scientifically substantiated opinion on the nature of the work of shot in destroying rock.