Geomechanical situation prediction in transition from open to underground mining of steeply dipping ore body by systems with caving

Bozymchak mine in Kyrgyzstan is currently transitioning from open pit to underground mining. The reserves are planned to be extracted within a limited time by sub-level caving systems. Due to the difficult geotechnical situation, there is an urgent need to analyze the geomechanical conditions in order to assess the level of danger of the existing and newly driven underground excavations. During the research, the geological conditions of the deposit and the design solutions of mining were analyzed. It is found that undermining of the pit by caving systems induces displacements and dynamic phenomena caused by the confining pressure. Mining in unstable serpentinite can cause air waves. When waste rocks are by-passed from the bottom of the pit, they are apt to arching. During extraction of the reserves from the temporary level pillar in the center of the deposit, especially on the lower horizons of the mine, there is a hazard of dynamic events generated by the confining pressure. It is found that the most dangerous elements of the geotechnology are the hanging wall, footwall and the temporary level pillar established in the center of the deposit. The recommended measures to ensure safety of mining operations include arrangement of permanent openings outside the displacement zone and implementation of geomechanical monitoring in preparatory, access and exploration drives. The internal dump in the pit can be controlled by remote surveying. When extracting reserves from the level pillar, it is advisable to undertake ground control by visual inspection and using instrumentation, to carry out destress blasting of the pillar, to monitor the lag of the lower sublevel mining front and to extract the reserves from the pillar by a single mine face. In mining operations in unstable rocks, it is recommended to localize voids by partitions made of caved gangue.

Keywords: stability of stopes and pillars, rock caving systems, hybrid geotechnologies, geomechanical monitoring, induced stresses, confining pressure, displacement.
For citation:

Avdeev A. N., Zoteev O. V., Sosnovskaya E. L. Geomechanical situation prediction in transition from open to underground mining of steeply dipping ore body by systems with caving. MIAB. Mining Inf. Anal. Bull. 2021;(5—2):6—15. [In Russ]. DOI: 10.25018/0236_1493_2021_52_0_6.

Acknowledgements:

The paper was prepared within the framework of state assignment № 075— 00581—19—00 on topic № 0405—2019—0007.

Issue number: 5
Year: 2021
Page number: 6-15
ISBN: 0236-1493
UDK: 622.831
DOI: 10.25018/0236_1493_2021_52_0_6
Article receipt date: 15.12.2020
Date of review receipt: 15.02.2021
Date of the editorial board′s decision on the article′s publishing: 10.04.2021
About authors:

Avdeev A. N., Cand. Sci. (Eng.), Senior Research Worker, e-mail: avdeev0706@mail.ru;
Zoteev O. V., Cand. Sci. (Geol. Mineral.), Principal scientist, e-mail: zoteev.o@mail.ru;
Sosnovskaya E. L., Cand. Sci. (Geol. Mineral.), Senior Research Worker;
Institute of Mining of the Ural Division of Russian Academy of Sciences, Ekaterinburg, Russia.

 

For contacts:
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