Quantitative estimation of scale effect is a complex problem which contained many uncertainties a... more Quantitative estimation of scale effect is a complex problem which contained many uncertainties and should be solved using probability calculus and statistical approach. This paper aims to derive the structural factor according statistical strength theory involving discontinuity surface conditions account to estimate the design rock mass strength. A short review of scale effect estimation techniques based on statistical strength theory is given. A new method of structural factor evaluation is proposed. This technique allows accounting discontinuity conditions by changing the variation of tested specimen random sample. A function that describes the decreasing of strength due to poor discontinuity surface quality is introduced to correct the initial and central statistical moments of strength random distribution. The evaluation of the joints condition function based on analysis of the results of uniaxial compressive strength tests and petrographic structure of specimens is shown. Impr...
Purpose. Creating a generalized algorithm to account for factors (coal seam thickness, enclosed r... more Purpose. Creating a generalized algorithm to account for factors (coal seam thickness, enclosed rock mechanical properties, the dimension and bearing capacity of artificial support patterns) causing a gateroad state under the effect of longwall face and goaf. Methods. The assessment of the gateroad stability is based on numerical simulation of the rock stress-strain state (SSS). The finite element method is used to find out the changes in the SSS of surrounding rocks at various stages of longwall mining. The elastic-plastic constitutive model and Hoek-Brown failure criterion implemented in codes RS2 and RS3 (Rocscience) are applied to determine rock displacements dependently on the coal seam thickness, enclosed rock strength, width and strength of artificial support (a packwall comprised of hardening mixture “BI-lining”). To specify the mechanical properties of the packwall material a series of experimental tests were conducted. A computational experiment dealing with 81 combination...
Purpose. To develop techniques for estimating the pit wall stability in terms of occurring of a z... more Purpose. To develop techniques for estimating the pit wall stability in terms of occurring of a zone of heavily jointed rock mass during ore mining at the Akzhal deposit (Kazakhstan), to work out measures to strengthen the rock opening and to verify the effectiveness of the developed measures. Methodology. The finite element analysis of the rock stress-strain state is implemented on the basis of the elastic-plastic model and the generalized Hoek-Brown failure criterion. The rock mass quality was assessed using the RMR and GSI rating classifications. This made it possible to simulate a zone of intense fracturing by changing the characteristics of the jointed surface. The shear strength reduction procedure was used to determine the safety factor for the quarry wall. Findings. The strain distributions in the rock mass forming the quarry wall have been obtained in terms of the Akzhal polymetallic ore deposit (Kazakhstan). The case of creating a zone of heavily jointed rocks in the area ...
Purpose. To identify development regularities related to a stress-strain state and stability of t... more Purpose. To identify development regularities related to a stress-strain state and stability of the open pit walls while mining the steeply inclined iron-ore body at various stages of mining considering deterministic and stochastic components of the rock mass structural heterogeneity. Methodology. Numerical 3D simulation of the rock stress-strain state; application of the strength reduction procedure to determine a safety factor, taking into account the rock mass heterogeneity based on a stochastic model. Findings. The distribution of maximum shear deformations and displacements within the rock mass, making up the pit wall, has been obtained. Potential slide surfaces and safety factors have been determined at various stages of the inclined ore body mining. The effect of the rock mass structure on the pit wall stability has been estimated. A comparison of calculations based on the 3D and 2D models has been carried out. The correction coefficient has been obtained, which allows using ...
References 1. Gajdaj O. Development technogenic deposits by the technology production of composit... more References 1. Gajdaj O. Development technogenic deposits by the technology production of composite fuel / O. Gajdaj, V. Ruskyh // Materials of the International Scientific & Practical Conference «Energy Efficiency and Energy Saving 2017» (Program of reports) Матеріали міжнародної науково-практичної конференції «Енергоефективність та енергозбереження 2017» (програма виступів); November 16–17, 2017, Ministry of Educ. & Science of Ukraine, National Mining University. – Dnipro: NMU, 2017. – P. 17–18. 2. Gayday O. Researches of structural-mechanical properties of coal tailings as disperse systems / O. Gayday // Annual Scientific-Technical Collection. Leiden, The Netherland. – Press/Balkema, 2013. – Р. 327–331. 3. Ruskyh, V.V., Gayday, A.A. (2013). O primenenii programmnogo obespechenija “MineModeler” v uslovijah shaht PAO DTEK «Pavlogradugol'». Sbornik nauchnyh trudov Visnyk Natsionalnoho Hirnychoho Universytetu, (41), 98-102. 4. Гайдай А. А., Сулаев В. И. Технология адгезионо-химиче...
Purpose. A methodology development for predicting the geomechanical situation when mining an ore ... more Purpose. A methodology development for predicting the geomechanical situation when mining an ore deposit with steep-dipping layers, taking into account the uncertainty in determining the rock properties, which is a consequence of the rock mass heterogeneity. Methods. The assessment of the open-pit wall stability is based on a combination of numerical simulation of the rock stress-strain state (SSS) and probabilistic analysis. The finite element method is used to determine the changes in the SSS that occur at various stages of mining operations due to design changes in the overall open-pit slope angle. The elastic-plastic model of the medium and the Mohr-Coulomb failure criterion are implemented in the codes of the 3D finite element analysis program RS3 (Rocscience). Stochastic simulation is used to assess random risks associated with natural object state variations. Findings. The distribution of maximum shear strains, which localizes the real or potential sliding surfaces in the ope...
This publication delves into geomechanical processes encountered during sequential longwall minin... more This publication delves into geomechanical processes encountered during sequential longwall mining of coal seams, with a unique focus on reusing the conveyor track of the prior longwall as the ventilation pathway for the subsequent longwall. An in-depth geomechanical rationale is provided for the reuse of excavations within jointed rock formations. To ascertain the critical roles played by various support and protective elements at each distinct mining stage, a comprehensive analysis is performed using finite element techniques to delineate the three-dimensional stress-strain characteristics of the rock mass. Employing an innovative methodology integrating multifactorial analysis, contemporary structural identification algorithms, and a neuroheuristic approach for predictive mathematical modeling, an integral stability metric for reusable mining excavations is introduced. Specifically, this metric quantifies the relative preservation of the excavation's cross-sectional area following its connection to the second longwall. Furthermore, the study tackles the challenge of nonlinear optimization through the application of the generalized reduced gradient method (Frank-Wolfe), ultimately deriving the optimal combination of factors that maximizes the preservation of the crosssectional area for these reusable excavations.
Quantitative estimation of scale effect is a complex problem which contained many uncertainties a... more Quantitative estimation of scale effect is a complex problem which contained many uncertainties and should be solved using probability calculus and statistical approach. This paper aims to derive the structural factor according statistical strength theory involving discontinuity surface conditions account to estimate the design rock mass strength. A short review of scale effect estimation techniques based on statistical strength theory is given. A new method of structural factor evaluation is proposed. This technique allows accounting discontinuity conditions by changing the variation of tested specimen random sample. A function that describes the decreasing of strength due to poor discontinuity surface quality is introduced to correct the initial and central statistical moments of strength random distribution. The evaluation of the joints condition function based on analysis of the results of uniaxial compressive strength tests and petrographic structure of specimens is shown. Impr...
Purpose. Creating a generalized algorithm to account for factors (coal seam thickness, enclosed r... more Purpose. Creating a generalized algorithm to account for factors (coal seam thickness, enclosed rock mechanical properties, the dimension and bearing capacity of artificial support patterns) causing a gateroad state under the effect of longwall face and goaf. Methods. The assessment of the gateroad stability is based on numerical simulation of the rock stress-strain state (SSS). The finite element method is used to find out the changes in the SSS of surrounding rocks at various stages of longwall mining. The elastic-plastic constitutive model and Hoek-Brown failure criterion implemented in codes RS2 and RS3 (Rocscience) are applied to determine rock displacements dependently on the coal seam thickness, enclosed rock strength, width and strength of artificial support (a packwall comprised of hardening mixture “BI-lining”). To specify the mechanical properties of the packwall material a series of experimental tests were conducted. A computational experiment dealing with 81 combination...
Purpose. To develop techniques for estimating the pit wall stability in terms of occurring of a z... more Purpose. To develop techniques for estimating the pit wall stability in terms of occurring of a zone of heavily jointed rock mass during ore mining at the Akzhal deposit (Kazakhstan), to work out measures to strengthen the rock opening and to verify the effectiveness of the developed measures. Methodology. The finite element analysis of the rock stress-strain state is implemented on the basis of the elastic-plastic model and the generalized Hoek-Brown failure criterion. The rock mass quality was assessed using the RMR and GSI rating classifications. This made it possible to simulate a zone of intense fracturing by changing the characteristics of the jointed surface. The shear strength reduction procedure was used to determine the safety factor for the quarry wall. Findings. The strain distributions in the rock mass forming the quarry wall have been obtained in terms of the Akzhal polymetallic ore deposit (Kazakhstan). The case of creating a zone of heavily jointed rocks in the area ...
Purpose. To identify development regularities related to a stress-strain state and stability of t... more Purpose. To identify development regularities related to a stress-strain state and stability of the open pit walls while mining the steeply inclined iron-ore body at various stages of mining considering deterministic and stochastic components of the rock mass structural heterogeneity. Methodology. Numerical 3D simulation of the rock stress-strain state; application of the strength reduction procedure to determine a safety factor, taking into account the rock mass heterogeneity based on a stochastic model. Findings. The distribution of maximum shear deformations and displacements within the rock mass, making up the pit wall, has been obtained. Potential slide surfaces and safety factors have been determined at various stages of the inclined ore body mining. The effect of the rock mass structure on the pit wall stability has been estimated. A comparison of calculations based on the 3D and 2D models has been carried out. The correction coefficient has been obtained, which allows using ...
References 1. Gajdaj O. Development technogenic deposits by the technology production of composit... more References 1. Gajdaj O. Development technogenic deposits by the technology production of composite fuel / O. Gajdaj, V. Ruskyh // Materials of the International Scientific & Practical Conference «Energy Efficiency and Energy Saving 2017» (Program of reports) Матеріали міжнародної науково-практичної конференції «Енергоефективність та енергозбереження 2017» (програма виступів); November 16–17, 2017, Ministry of Educ. & Science of Ukraine, National Mining University. – Dnipro: NMU, 2017. – P. 17–18. 2. Gayday O. Researches of structural-mechanical properties of coal tailings as disperse systems / O. Gayday // Annual Scientific-Technical Collection. Leiden, The Netherland. – Press/Balkema, 2013. – Р. 327–331. 3. Ruskyh, V.V., Gayday, A.A. (2013). O primenenii programmnogo obespechenija “MineModeler” v uslovijah shaht PAO DTEK «Pavlogradugol'». Sbornik nauchnyh trudov Visnyk Natsionalnoho Hirnychoho Universytetu, (41), 98-102. 4. Гайдай А. А., Сулаев В. И. Технология адгезионо-химиче...
Purpose. A methodology development for predicting the geomechanical situation when mining an ore ... more Purpose. A methodology development for predicting the geomechanical situation when mining an ore deposit with steep-dipping layers, taking into account the uncertainty in determining the rock properties, which is a consequence of the rock mass heterogeneity. Methods. The assessment of the open-pit wall stability is based on a combination of numerical simulation of the rock stress-strain state (SSS) and probabilistic analysis. The finite element method is used to determine the changes in the SSS that occur at various stages of mining operations due to design changes in the overall open-pit slope angle. The elastic-plastic model of the medium and the Mohr-Coulomb failure criterion are implemented in the codes of the 3D finite element analysis program RS3 (Rocscience). Stochastic simulation is used to assess random risks associated with natural object state variations. Findings. The distribution of maximum shear strains, which localizes the real or potential sliding surfaces in the ope...
This publication delves into geomechanical processes encountered during sequential longwall minin... more This publication delves into geomechanical processes encountered during sequential longwall mining of coal seams, with a unique focus on reusing the conveyor track of the prior longwall as the ventilation pathway for the subsequent longwall. An in-depth geomechanical rationale is provided for the reuse of excavations within jointed rock formations. To ascertain the critical roles played by various support and protective elements at each distinct mining stage, a comprehensive analysis is performed using finite element techniques to delineate the three-dimensional stress-strain characteristics of the rock mass. Employing an innovative methodology integrating multifactorial analysis, contemporary structural identification algorithms, and a neuroheuristic approach for predictive mathematical modeling, an integral stability metric for reusable mining excavations is introduced. Specifically, this metric quantifies the relative preservation of the excavation's cross-sectional area following its connection to the second longwall. Furthermore, the study tackles the challenge of nonlinear optimization through the application of the generalized reduced gradient method (Frank-Wolfe), ultimately deriving the optimal combination of factors that maximizes the preservation of the crosssectional area for these reusable excavations.
Uploads
Papers by Dmytro Babets