Кафедра Галузеве машинобудування ДМетІ (з 2022 р. утворилась шляхом з'єднання кафедри Колісних і гусеничних транспортних засобів та кафедри Машини та агрегати металургійного виробництва)

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http://crust.ust.edu.ua/handle/123456789/16490

ENG: Faculty of Machine Design and Environmental Protection Dnipro Metallurgical Institute

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Fracture Diagrams of Prismatic Specimens with an Improved Contact Stress Distribution Law
(IOP Publishing Ltd, 2022) Vasyliev, Leonid; Vasyliev, Dmytro; Malich, Mykola H.; Zhuravkov, Mikhail; Katan, Volodymyr
ENG: The authors have previously improved the principles of distribution of contact normal and tangential stresses at the moment of destruction of the specimen on the basis of L. Prandtl's method as applied to rocks. The article presents further development of the method for constructing out-of-limit curves of "stress - longitudinal deformation" diagrams of rocks. A comparative assessment of the proposed method for calculating diagrams in comparison with diagrams has been constructed by E.P.Unksov method. It has been found that the parameters of the diagrams differ in numerical values in direction of increasing the reliability. Comparison of the calculated diagrams "stress - ordinate of the crack tip" and "stress - deformation" according to the improved method and the method of E.P. Unksov testifies that the level of the current strength values decreases with the development of two cracks at small angles of internal friction. The proposed method allows to determine the ultimate strength and residual strength of rock samples using their shear strength, internal, and contact friction coefficients, elastic modulus, which by simple methods can be established experimentally in laboratories of mining enterprises. The results can be used to control the state of the rock mass and effective destruction during disintegration.
Improving a Technique to Calculate Strength of Cylindrical Rock Samples in Terms of Uniaxial Compression
(Dnipro University of Technology, Dnipro, Ukraine, 2023) Vasyliev, Leonid; Malich, Mykola G.; Vasyliev, Dmytro; Katan, Volodymyr; Rizo, Zahar
ENG: Purpose is to improve analytical technique to calculate strength of cylindrical rock samples taking into consideration standard horizontal stresses. Methods. Mathematical modeling of cylindrical rock sample breakage under the truncated-wedge destruction was performed taking into consideration the standard horizontal stresses using four experimental characteristics (i.e. k being shear strength; fс and μ being contact and internal friction coefficients; and Е being elasticity modulus) as well as comparing the design strength with experimental data obtained in the process of uniaxial compression. Findings. The technique makes it possible to identify both maximum strength and residual strength of cylindrical rock samples using four indicators of properties which can be simply defined by experiment. Comparison of the analytical strength limits and experimental data, obtained in terms of uniaxial compression, supports the idea of high efficiency of the proposed technique. Originality. For the first time, analytical modeling of cylindrical rock sample breakage has been performed in terms of the truncated-wedge destruction taking into consideration the standard horizontal stresses as well as contact and internal friction parameters. Practical implications. The technique advantage is to apply promptly the calculation results in the context of industrial enterprises since their environment helps apply simple procedures to define indices of physiсomechanical characteristics of rocks for determination of stability of underground structures and reduction of energy consumption while disintegrating in open pits and mining and processing complexes.

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