Problems of ultimate pit limit design

The paper considers the problems of long-term stability of pit wall at the ultimate limits. The recommendations on drilling and blasting at the ultimate pit limits are based on geological studies, field engineering and geological exploration of structure and tectonics of rock mass, detection of unfavorably oriented weakening surfaces and on the pit wall stability estimates. The studies into adjacent rock mass deformation under multi-row short-delay blasting made it possible to develop the methods for improving the fragmentation quality of blasted rock mass by reducing the blast energy transmitted to pit wall rock mass, the calculation procedure of delay intervals between blasts and the blasting patterns for pit wall rock mass which ensured long-term stability of benches as a result of decreased explosive rupture of pit wall rock mass. At ultimate pit limits, the blast load applied to the pit wall rock mass can be reduced by using the diagonal blasting patterns and by increasing the delay intervals. To reduce the probability of pit wall failure, including the zone of permanent access roadways, it is recommended to operate at the ultimate pit limits based on the studies on rock mass structure with mapping the unfavorably oriented cracks and faults, pit wall stability estimates and adjustment of pit wall deign parameters.

Yakovlev A. V., Shimkiv E. S. Problems of ultimate pit limit design. MIAB. Mining Inf. Anal. Bull. 2021;(5—1):105—116. [In Russ]. DOI: 10.25018/0236_1493_2021_51_0_105.

The article is prepared under the State Contract on Methods to Take into Account Transient Technological Processes in Mining Deep-Sated Mineral Deposits of Complex Structure, Topic No. 0405-2019-0005.

Yakovlev A. V., Cand. Sci. (Eng.), Head of Laboratory of Open Geotechnology,
Shimkiv E. S., Researcher;
Institute of Mining, Ural Branch of RAS, Ekaterinburg, Ruusia, lubk_igd@mail.ru.

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