Yakutniproalmaz Institute, ALROSA, Mirny, Russia:

I. B. Bokiy, Head of Laboratory, Associate Professor, Candidate of Physico-Mathematical Sciences, bokiyib@alrosa.ru
O. V. Zoteev, Chief Researcher, Professor, Doctor of Engineering Sciences
V. V. Pul, Leading Production Design Engineer

The geological structure of the Aikhal kimberlite pipe mined by ALROSA is characterized. The mining system of the deposit is described, where the upper block of the pipe is mined using open pit method and the deep-lying reserves are extracted by underground method with backfilling. Previously, the upper levels of the ore body were mined by open stoping with blind entry drifts, and further on, the transition to the room-and-pillar method was executed. The transition zone between the open stoping and room-and-pillar areas was mined out completely. The authors performed mathematical modeling of the stress–strain behavior in the fill mass in the transition zone. The modeling was carried out by the finite element method using Phase 2 software. The modeling shows the admissible range of the stability criterion and vertical subsidence in stopes during rock backfilling. However, the data analysis points at the necessity to take into account incomplete backfill, which can contribute to joining of caving zones in adjacent chambers. In this regard, the relevant recommendations for safe mining operations are made.

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