Rockburst Hazard of Rock Mass during Mining under Open Pit Bottom at Sayak-1 Deposit
S. N. Shaposhnik1, Yu. N. Shaposhnik2, P. A. Tsoi2, A. A. A. A. Neverov2
1Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
2East Kazakhstan Technical University, Ust-Kamenogorsk, Kazakhstan
Keywords: Rock mass, strength and deformation characteristics, stresses, rockburst hazard
Abstract
Rockburst hazard of mining operations under an open pit bottom at Sayak-1 deposit is assessed. Mining practices use the room-and-pillar system down to a depth of 295 m below the pit bottom. At the present time, pit bottom rock mass of the Central Sayak deposit holds reserves mostly in ore pillars. Single events of dynamic behavior due to the action of rock pressure were recorded in the course of mining. The strength and deformation characteristics of rocks are determined in a laboratory environment. It is found that core samples are prone to rockburst hazard. The natural stresses at the deposit are measured using the hydraulic fracturing method. RQD index of rock mass is determined. The rock mass is of fair and good quality. The average uniaxial compression strength of rocks is 95.85 MPa. By Kaiser’s criterion, rockburst hazard is absent at the deposit and dynamic failure events are unlikely as a consequence. For all rockburst-hazardous types of rocks at the deposit to the depth of 295 m, the coefficient K characterizing rockburst hazard is lower than the critical value. The level of the maximal stresses induced by mining operations is insufficient to provoke dynamic events in rock mass.
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