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Numerical Crack Analysis of Blunt Rock Indenters by an Indirect Boundary Element Method

Geomaterials 2013年第4期3卷 132-137页

作者： narges sadat tayarani Mohammad Fatehi Marji Faculty of Mining and Metallurgy Yazd University Yazd Iran Mine Exploitation Engineering Department Faculty of Mining and Metallurgy Yazd University Yazd Iran

Linear elastic fracture mechanics principles are widely applied for the analysis of crack problems in rock fracture mechanics. Rock indentation is an important and complicated problem among rock engineering issues. In this paper, in addition to the fracture criterion of maximum tangential stress adjacent to crack tip, the higher order displacement discontinuity method (which is a version of the indirect boundary element method) has been used for modeling the crack propagation mechanism under blunt indenters. In order to achieve more accurate results, higher order boundary elements i.e. quadratic elements, has been used to calculate displacement discontinuities and also to reduce the singularities of stress and displacement fields near the crack tip, the special crack tip elements has been used to calculate the stress intensity factors (SIF) at the crack tips. In this modeling, the effect of crack angle on stress intensity factors has been investigated. The numerical results of stress intensity factors obtained from some example problems were compared to the theoretical and experimental results cited in the literature which always show a percentage error less than one percent. The simulated results may pave the way for increasing the efficiency of mining and drilling by improving the design of tools and indentation equipments.

关键词： Numerical Modeling Boundary Element Method Rock Indentation Linear Elastic Fracture Mechanics (LEFM)

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Application of artificial neural networks to the prediction of tunnel boring machine penetration rate

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Mining Science and Technology 2010年第5期20卷 727-733页

作者： JAVAD Gholamnejad narges tayarani Department of Mining and Metallurgical Engineering Yazd University Mining & Metallurgical Engineering Yazd University

Rate of penetration of a Tunnel Boring Machine(TBM) in a rock environment is generally a key parameter for the successful accomplishment of a tunneling *** paper presents the results of a study into the application of an Artificial Neural Network(ANN) technique for modeling the penetration rate of tunnel boring machines.A database,including actual,measured TBM penetration rates,uniaxial compressive strengths of the rock,the distance between planes of weakness in the rock mass and rock quality designation was *** collected from three different TBM projects(the Queens Water Tunnel,USA,the Karaj-Tehran water transfer tunnel,Iran,and the Gilgel Gibe II hydroelectric project,Ethiopia).A five-layer ANN was found to be optimum,with an architecture of three neurons in the input layer,9,7 and 3 neurons in the first,second and third hidden layers,respectively,and one neuron in the output *** correlation coefficient determined for penetration rate predicted by the ANN was 0.94.

关键词： artificial neural networks TBM tunneling penetration rate modeling

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