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. Beydin, Senior Lecturer

Underground mineral mining uses technologies that may result in caving of host rocks or dirt fill, or ore in a mined-out void (mining with shrinkage, underground block leaching). In this respect, it is important to know deformation characteristics of broken rocks and influence of these characteristics on stress state of surrounding rock mass. Computer-aided mathematical modeling of stress state of rocks involves different deformation characteristics. The accuracy requirements imposed on the determination of indexes included in these characteristics are raised. One of the most critical deformation characteristics of rocks is Poisson’s ratio that characterizes cross-deformation of a medium, in particular, crushed ore. There are merely a few studies into Poisson’s ratio of crushed hard rocks. This is associated with the inadaptability of Poisson’s ratio procedures developed for dispersed soil, in the majority of cases, and with the technical difficulties. The aim of this study is the determination of Poisson’s ratio in crushed hard rocks of various grain-size composition using the method of belt. In the proposed modified method, a steel belt fixed horizontally or vertically relative to ore in a ring under load was kept immovable, the ring with ore was forced to move horizontally, and the force initiating the movement was measured. This approach allowed higher accuracy of the measurement. The results were used to determine the lateral earth pressure coefficient and Poisson’s ratio. The article reports experimental results on the determination of the lateral earth pressure coefficient and Poisson’s ratio of crushed hard rocks of various grain-size composition, which should be included in the modeling of rock mass stresses.
This study has been supported by the Ministry of Education and Science of the Russian Federation within the Project on Integrated Geotechnology for Low-Grade Economic Uranium Ore Reserves.

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