Transbaikal State University, Chita, Russia:
V. M. Lizunkin, Professor, Doctor of Engineering Sciences
V. A. Babello, Professor, Doctor of Engineering Sciences
M. V. Lizunkin, Associate Professor, Candidate of Engineering Sciences, LMV1972@mail.ru
A. V. Beidin, Senior Lecturer

In some underground mining methods, it often happens that caved rocks or backfill made of gangue, or broken ore occur in a mined-out area (e.g. shrinkage stoping, in-situ leaching). Accordingly, it is important to know features of variation in the strength properties of such rocks and their influence on stress state of enclosing rock mass. The computer-aided mathematical modeling of stress/strain state involves various characteristics of mechanical properties of rocks. In this connection, higher requirements are imposed on reliability of determination of characteristics of these properties. Among the most important characteristics of strength of rocks and, in particular, broken ore, there are the internal friction angle and cohesion. At the same time, the research into strength of broken hard rocks is deficient due to complexity and high labor content of the in situ investigations, as a rule. This study aimed to determine characteristics of strength properties of hard broken rocks of various grain-size compositions. A feature of the experimental procedure was the purpose-made large-scale test bench used to eliminate the influence of scale factor on the experimental results. In the tests, the method of solid ore block shear was implemented. The article provides the results of the experimental research into the strength parameters of hard broken rocks of various grain-size compositions. The obtained data should be taken into account in modeling stress state of rocks.

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