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

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Analytical Method for Calculating Parameters of Destruction Diagrams of Cylindrical Rock Samples with Their Wedge Form of Destruction
(Wroclaw University of Technology, Wroclaw, Poland, 2025) Vasyliev, Leonid; Rizo, Zakhar; Vasyliev, Dmytro; Kress, Denys; Krasovskyi, Ihor; Katan, Volodymyr; Malich, Mykola H.
ENG: This study aims to develop an analytical method for calculating the parameters of destruction diagrams of cylindrical rock samples experiencing wedge-shaped fractures, facilitating the effective disintegration of rocks. The method employs analytical modeling to simulate the destruction process of cylindrical rock samples, leveraging experimental values of four key rock properties: shear resistance limit, internal friction coefficient, external friction coefficient, and elastic modulus. The proposed method accurately determines the limit and residual strength of the rock samples using these four indicators, which can be experimentally obtained through straightforward procedures in mining enterprises. This research marks the first instance of analytically modeling the destruction of cylindrical rock samples with wedge-shaped fractures while accounting for both internal and external friction. The practical application of this method allows for the rapid assessment of stress-strain parameters in rock samples, thereby enhancing the efficiency of rock disintegration processes in mining operations.
Fracture Diagrams of Prismatic Specimens with a Refined Contact Stress Distribution Law
(M.S. Poliakov Institute of Geotechnical Mechanics of the National Academy of Sciences of Ukraine, Dnipro, 2025) Malich, Mykola H.; Katan, Volodymyr; Laikov, Dmytro V.; Kravchenko, Kostiantin
ENG: The extraction and further processing of minerals are associated with the improvement of existing and development of new resource-saving technological solutions for underground and open-cycle operationsThe most costly technology for processing mineral raw materials is destruction itself, which accounts for about 20% of total electricity production and up to 50% of total capital and operating costs. To determine the stability of the rock mass in an ultimate state, a stress-strain diagram of rock is used. To analyse these diagrams, it is necessary to know the distribution of contact normal and tangential stresses. According to classical solutions to this problem, the stress distribution was determined using the methods of L. Prandtl and E.P. Unksov. However, these methods did not account for the occurrence of stresses perpendicular to the compression vector. The article provides further development of the method for refining the distribution of contact stresses and constructing a “normal stress-longitudinal deformation” diagram and limit curves, taking into account contact friction under load. A comparative assessment of the proposed method with diagrams constructed using the classical method is carried out. The proposed method allows determining the strength limit and residual strength of rock samples based on parameters that can be easily established experimentally in the laboratories of mining enterprises. The results can be used to monitor the condition of the rock mass and ensure effective rock destruction. Therefore, an improved method for determining the distribution of contact normal and tangential stresses in prismatic samples of brittle, relatively homogeneous rocks under stress is proposed, which takes into account stresses perpendicular to the load vector and allows for a more accurate assessment of the stress-deformed state of the samples taking into account contact. It has been established that, especially at small angles of internal friction, the level of current stresses according to the proposed method is lower than that obtained using classical solutions. The developed approach allows avoiding the influence of the scale effect and transferring the results of laboratory studies to real, undamaged and relatively homogeneous arrays. The results are of practical importance for assessing the stability of rock masses and improving the efficiency of rock destruction during the extraction and processing of solid minerals.
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.