Stress State of Rocks Surrounding Excavation under Variable Young Modulus
M. V. KURLENYA, V. E. MIRENKOV, A. A. KRASNOVSKY
Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Krasnyi pr. 4, Novosibirsk, 630091 Russia
Keywords: выработка, порода, большая глубина, физические эффекты, модуль Юнга, граничные условия, аналитическое решение, система сингулярных интегральных уравнений, excavation, rock, great depth, physical effects, Young modulus, boundary conditions, analytical solution, singular integral equations system
Abstract
Deep-level mining needs extra data on physical behavior of rocks at great depths (under high stresses). Without such data, any computations for deep-level technologies based on analogy with shallow-depth technologies are non-diagnostic. Elastic moduli of rocks may depend on the accumulated plastic deformation and their reduction is considerable in the known tests of metals. It seems interesting to study the influence of this property of rocks on distribution of residual stresses and displacements. Elastic transformation of an excavation after drivage (relief of stresses) largely affects surrounding rock mass and results in origination of a transition layer around the excavation. A local drop of deformation energy takes place in the surrounding rocks, which reduces stress concentration. The problem is studied based on an analytical solution obtained for a deep round excavation subjected to constant value compressive stresses at infinity and a solution taking into account the Young modulus. The article offers an algorithm for geomechanical condition of tocks and determines ranges for stresses and displacements in the zone of influence of excavation. Examples of calculations are given, and the results are discussed.
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