Belgorod State University, Belgorod, Russia

V. N. Tyupin, Doctor of Engineering Sciences, Professor, tyupinvn@mail.ru

VIOGEM, Belgorod, Russia
E. B. Yanitsky, Deputy CEO, Candidate of Geographical Sciences

Experience of contour blasting in dry dock granite gneiss shows that when using the same parameters (linear mass of explosive charge, distance between contour wells), they are effective in jointed rocks with a block size de = 0.5–1.5 m. In rock mass with de = 0.1–0.5 m, rocks constituting the blasting perimeter get damaged and collapsed, which leads to the need to develop blast designs for rock masses with varying degrees of fracturing. The review of literature sources shows that contour blast designs miss some effective parameters. The formulas for calculating the contour blasting parameters and the size of the damage zone (roof breaks) depending on the strength of rocks, jointing degree, as well on the detonation and geometry parameters of explosives charges are given. The contour blasting parameters and the size of the zone of roof breaks are calculated for dry dock granite gneiss rock mass of varying jointing degree. Taking into account the fact of disturbance caused by contour blasting to jointed rock mass, in order to ensure safety, in the upper and less critical part of the dry dock pit, in rocks of jointing categories I–II, the long-term stability is ensured by rock bolting and mesh reinforcement. In the lower and most critical part of the dry dock rock mass, regardless of the jointing category, the lining of slopes is made using monolithic reinforced concrete with a thickness of 500 mm. It is necessary to conduct further industrial tests of contour blasting in rock masses with varying degrees of jointing.

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