ON MECHANISM AND DEGREE OF IMPACT OF THE INTERMEDIATE MAIN STRESS ON THE STRENGTH OF ROCKS

Abstract

The paper describes one of the oldest and primary tasks of geomechanics and rock mechanics — determining the mechanism of influence of the intermediate main stress on the rock strength at shear in the volume unequalcomponent stress state. To date, there is only an approximate estimate of this influence (0 — 15%), but the mechanism of this influence is unknown. At the same time,
understanding of the physics of the process of increasing
the strength in the nipped medium (intermediate main
stress) will allow to calculate more correctly the stability
of the nipped slopes or the slopes of open-pit mine sides in
tectonically stressed rock masses, as well to predict the
parameters of the shear process, etc. In the vast majority
of cases, when justifying the limit parameters of elements
of underground mining systems, the action of intermediate
main stress is also not considered, which is also connected
with lack of mathematical models of its accounting. The
mentioned factors determine the relevance of the research
topic and the necessity of their conduct as a practice. The
aim of the work is to determine the physical bases and
quantitative estimates of the influence of the intermediate
main stress on the rock shear strength. By means of generalized Guk law and the results of previously performed studies as well as experimental data the paper proposes the analytical dependences determining the
degre of rock strengthening from the action of the intermediate main stress. The paper has justified the
maximum value of the strength increase from the action of
the intermediate stress. The given results are mostly theoretical, although they show correct results in the first
approximation. They are therefore subject to further
adjustment and refinement in comparison with the
experimental data.