Reducing the impact of mass explosions on the contour array of the quarry

Abstract

The increase in the depth of the quarries revealed an important problem of maintaining the stability of the sides of the quarries due to changes in the structure of the rock mass under the influence of industrial mass explosions both directly in the fracture zone, revealing closed cracks, and by wave influence in the pre-collapse zone at a considerable distance, where new cracks and prerequisites for the creation of crack nuclei are generated. Blasting operations near slope structures without taking into account these changes in the massif often causes a violation of their stability, the occurrence of landslides, up to catastrophic. It is proved that with explosive masses on underground blocks up to tens of tons, the effect of their explosions on the array can be traced to at least 50 m, with intensive decompression up to 20 m. Consequently, in quarries with explosive masses on blocks of hundreds and even thousands of tons of explosives, even greater “long-range” distances should be expected. In most cases, the protection of the sides of quarries from the effects of mass explosions is carried out by mowing down the sides of the quarry, preceding a mass explosion in the instrument area. The paper proposes a new technology for conducting mass explosions with downhole detonation along the work front and the start of the explosion from the side of the quarry to the slope of the ledge, due to the constant deep clamping of exploding charges by an array of rocks of the untouched part of the block. Its main advantage is a threefold reduction in the effects of stress waves in the direction of the side of the quarry. Ten years of experience in using such technology has made it possible to form a stable side of the quarry on the limit contour without the use of additional measures to mow the side.