GENERALIZEDCRITERION OF CRACKINITIATION IN TERMS OF OSCILLAIONS IN STRESS STRAINROCK MASS
Journal Title: Вісник Кременчуцького національного університету імені Михайла Остроградського - Year 2017, Vol 1, Issue 102
Abstract
Purpose. To develop a generalized criterion of the crack initiation in terms of oscillations, which are distributed in the rock mass. To study the influence exerted on the cracks development in terms of oscillatory processes in stress strainrock mass. Methodology. The methodological basis of the solution of the problem is the space-time criterion used in the theory of brittle fracture. Results. We have derived a generalized criterion of the crack initiation at changing the parameters are in this criterion. The crack is influenced by a harmonic oscillating stresses. We have investigated the function of the length of the crack, which initiated (the critical length), from the stress parameters and characteristics of the rock mass. We have shown the ability and analyzed the conditions of a jump of the critical crack length. Such con- ditions in the case of the rock stress can be regarded as the rapid development of the rock breaking. We have proposed a generalized criterion of the crack initiation, which takes into account the physical characteristics of the rock mass and the stress parameters, in order to evaluate the possibility of such a situation. Originality. The theoretical basis for the transition criterion of rock mass in a critical state is not sufficiently developed in terms of the danger of dynamic phe- nomena (sudden outburst of the coal and gas, rock burst). Earlier we have investigated the possibility of the crack initia- tion at tensile load (2014). In this paper, we have proposed a generalized criterion of the crack initiation at any load in the rock mass. Practical value. The results obtained in the study of a criterion of the crack initiation, can be used to improve the acoustic forecast of the gas-dynamic phenomena on the amplitude-frequency characteristics. For this pur- pose, we have defined ranges frequencies of the harmonic oscillation for some rocks (grained sandstone, limestone, aleurolite, coal) in which there is the initiating of "short" cracks. Also we have defined the real conditions (for coal), in which a slight change in the oscillation amplitude in the rock mass leads to the effect of changes in the lengths of the cracks in the form of jump.
Authors and Affiliations
Yu. Golovko, E. Sdvyzhkova, D. Klymenko
Keywords
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