Belgorod National Research University, Belgorod, Russia:

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

The article informs on dynamic events due to rock pressure in mines of Priargun Mining and Chemical Association, and on their types. These dynamic events mostly take places in granite basal complex at a depth more than 500 m below ground surface. It is pointed at higher horizontal stresses induced by tectonics of the Indian and Eurasian Platforms. Antei granite deposit is cut by north-eastward orebearing faults into narrow north-eastward tectonic blocks. Dynamic events due to rock pressure occur most frequently when mining is carried out top-down, in blocks divided into two sublevels, with cemented backfill. The interchamber pillars less than 12–15 m high are rockburst-hazardous. Dynamic events take place in such pillars in the form of bumps. This study aims to develop safe and efficient method to unload interchamber pillars using blast energy. A blast influences stress state in fractured rock mass in three ways: relief of rocks near explosive charge and in-between the charge and exposure, loading in the direction from the charge into the depth of rock mass and initiation of dynamic events due to rock pressure in high-stress areas at the exposure. Physically, relaxation of rockburst-hazardous pillars at active faults by blasting consists in displacement of the foot wall of a fault relative to its hanging wall by means of short-delayed blasting. Concurrently, crumpling (squeezing) of rigid contacts at the fault edges takes place. The theoretical formulas to find blast hole spacing and delay intervals are proposed. The application of the method of rockburst-hazardous pillar unloading has proved its efficiency in terms of mine safety (22 pillars with a general area of 22 thou m² relieved). With this method, the cost of rock mass relaxation by drilling-and-blasting is cut down.

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