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On the accuracy of higher order displacement discontinuity method(HODDM) in the solution of linear elastic fracture mechanics problems

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Journal of Central South University 2016年第11期23卷 2941-2950页

作者： Abolfazl Abdollahipour Mohammad Fatehi Marji Alireza Yarahmadi Bafghi javad gholamnejad Faculty of Mining and Metallurgical Engineering Yazd University

The higher order displacement discontinuity method(HODDM) utilizing special crack tip elements has been used in the solution of linear elastic fracture mechanics(LEFM) problems. The paper has selected several example problems from the fracture mechanics literature(with available analytical solutions) including center slant crack in an infinite and finite body, single and double edge cracks, cracks emanating from a circular hole. The numerical values of Mode Ⅰ and Mode Ⅱ SIFs for these problems using HODDM are in excellent agreement with analytical results(reaching up to 0.001% deviation from their analytical results). The HODDM is also compared with the XFEM and a modified XFEM results. The results show that the HODDM needs a considerably lower computational effort(with less than 400 nodes) than the XFEM and the modified XFEM(which needs more than 10000 nodes) to reach a much higher accuracy. The proposed HODDM offers higher accuracy and lower computation effort for a wide range of problems in LEFM.

关键词： accuracy higher order displacement discontinuity method LEFM mode Ⅰ stress intensity factor mode Ⅱ stress intensity factor

Reserve estimation of the high phosphorous stockpile at the Choghart iron mine of Iran using geostatistical modeling

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Mining Science and Technology 2010年第6期20卷 855-860页

作者： KASMAEE Sara gholamnejad javad YARAHMADI Alireza MOJTAHEDZADEH Hosein Department of Mining and Metallurgical Engineering Yazd University

An attempt to estimate the reserves in the High Phosphorous stockpile （HP） at the Choghart Iron mine of Iran was carded out using geostatistical modeling. Grade and tonnage estimates of ore stockpiles can help convert them into a valuable ore reserve. This is valuable in consideration of increasing metal demand, and the depletion of in situ ore reserves, around the world. Estimation of reserves in stockpiles is difficult partly because of geological and grade discontinuities created during the dumping of the ore piles. Data input for the HP stockpile at Choghart was performed based upon pre-existing information gathered during extraction from the various mining benches. After establishing the input data files the reserve estimates were found using geostatistical methods aided by the international mining software SURPAC. The stockpile was divided in to three domains and the reserves in each domain were estimated separately. A grade block model was used to compute the reserve. Fe% and P% were estimated using the Ordinary Kriging method. The results showed that the total tonnage of the HP stockpile is 4.5 million tons with an average zrade of 55% Fe and 1.03% P.

关键词： stockpile reserve estimation geostatistics Ordinary Kriging

DEM simulation of confining pressure effects on crack opening displacement in hydraulic fracturing

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International Journal of Mining Science and Technology 2016年第4期26卷 557-561页

作者： Abdollahipour Abolfazl Fatehi Marji Mohammad Yarahmadi Bafghi Alireza gholamnejad javad Faculty of Mining and Metallurgical Engineering Yazd University

Hydraulic fracture is one of the key methods in well stimulation to increase production of oil and *** Opening Displacement(COD) is of great importance in this method since it is in direct relation with permeability and production *** this paper COD is measured by a distinct element model which has been validated by an exact solution.A comprehensive study has been performed on confining pressure effect on COD which is neglected in the analytical *** results showed that confining pressure considerably affects COD.A multi-parameter regression(considering effect of confining pressure,rock mass properties and fluid pressure) was performed on numerical results which resulted in an *** proposed equation considers the effect of confining pressure and its results are in good agreement with numerical results.

关键词： Hydraulic lracture COD Numerical analysis Confining pressure Regression