Basic Characteristics of the Stages of Rock Massif Destruction by Explosive Crushing

摘要

For definition of the most essential characteristics of mechanical interaction of the explosion products with environment it is possible to consider according to the C. I. Petrovsky model three-stage destruction of strong rock mass by explosion of blasthole charges. At the first stage the powerful compression wave, formed by explosion, destroys rock on the contact "charge-environment", from the crushing zone border the zone of radial cracks spreads. In the beginning process differs a little from the phenomena accompanying explosion in the boundless environment, but interaction of compression wave with a free surface leads to more intensive crushing of massif. This stage is short-term, but during this time the most part of energy of explosives is spent During this stage basic destruction of the breaking layer is carried out and inducer cavity of cylindrical form reaches the limited volume. At the second stage owing to a free surface influence axially symmetrical development of cavity is broken. Caseous products of explosion impart to the destroyed part of massif the accelerated movement towards a free surface. Action of the explosion products remained in a cavity is the main defining factor at this stage. The third stage is inertial scattering of rock in the gravity field, formation of disintegration of the broken rock. By our theoretical researches it was defined that the basic physical characteristic of the first stage is the limited radius of the explosive cavity, which take into account end result of explosion action in rock. The main physical characteristic of the second and the third stages is initial speed of movement of the centre of mass of the blown up part as predetermining rocks interposition in disintegration. In the paper the analytical dependences are adduced for definition of the indicated characteristics. They interconnect the sought characteristics with elastic and strength properties of rocks, with the detonation, physical and chemical characteristics of applied explosive and parameters of the charge location in massif.