THE VARIANTS OF ADVANCED UNLOADING ZONE CREATION ON THE DEEP LEVELS OF THE KUKISVUMCHORR DEPOSIT
The results of geomechanical assessment of mining on the deep levels of the Kukisvum- chorr apatite-nepheline deposit are presented in the paper. The deposit is developed by underground induced block and sublevel caving. Mining operations are carried out in highly stressed rock mass which leads to dynamic manifestations of rock pressure. Due to geological and mining conditions block ore reserves are separated into 3 technological zones: in the hanging wall, in the middle part and in the hanging wall of the ore body. The block ore reserves are supposed to be mined with advance in the hanging wall. This mining sequence allows decreasing the rockburst hazard level in other technological zones. The ore body area in the hanging wall is a zone of increased rock pressure. That is why the optimal choice of a mining method for this zone determines mining safety and efficiency in all block. The study has analyzed both the block and sublevel caving. The authors have used a numerical modeling method for predictive assessing the rock mass stress state. The set of finite element models has been developed which allows accounting both the regional particularities in stress distribution and parameters of mining technology elements in two mining methods. Sigma GT software developed in Mining Institute KSC RAS was used for studying the rock mass stress-strain state. As follows from the analysis of numerical modelling results the sublevel caving method is the most optimal method for mining in the hanging wall of the Kukisvumchorr deposit.