The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Deguang Meng - One of the best experts on this subject based on the ideXlab platform.
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Experimental and Numerical Investigation of Hard Rock Breakage by Indenter Impact
Shock and Vibration, 2020Co-Authors: Hongxiang Jiang, Cai Zhiyuan, Wang Ouguo, Deguang MengAbstract:To investigate the effect of indenter shape, impact energy, and impact velocity on the Rock Breakage performance, a test device for Rock fragmentation by indenter impact was developed to obtain the Rock Breakage volume, depth, and area under different impact conditions. By comparing the Rock Breakage volume, depth, area, and specific energy consumption, the results show that indenter shape has a greater influence on the Rock Breakage performance than that of the impact velocity with the same impact energy, and impact energy plays a decisive role in Rock Breakage performance with an identical indenter shape and impact velocity. For the lowest to highest specific energy consumption, the order of indenter shape is cusp-conical, warhead, hemispherical, spherical-arc, and flat-top under the same impact energy and velocity, but the cusp-conical indenter is damaged after several impacts. The Rock Breakage volume, depth, and area all increase with the increase in impact energy, but the effect of the impact velocity could be ignored under the same impact energy. In addition, the Rock Breakage features of the numerical simulation and experiments are similar, which show that the crushing zone close to the indenter impact point is mainly caused by the high compressive stress, and then radial cracks are caused by the accumulative energy release. The findings of this study will contribute to progress in the performance and efficiency for percussive Rock drilling.
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Numerical investigation of hard Rock Breakage by high-pressure water jet assisted indenter impact using the coupled SPH/FEM method
Powder Technology, 2020Co-Authors: Hongxiang Jiang, Wang Ouguo, Zhao Huihe, Kuidong Gao, Wang Yongxin, Deguang MengAbstract:Abstract To investigate the effect of high-pressure water jet assistance on hard Rock Breakage by mechanical impact, a rate-dependent constitutive model was adopted to describe the mechanical behavior of the Rock. Then, a numerical model of Rock Breakage was developed using the coupled smoothed particle hydrodynamics (SPH) and finite element method (FEM). The indenter and Rock stress and Rock Breakage features were used to evaluate the assisted effect of the high-pressure water jet. The Rock stress perturbation by water jet assistance was more intense than that by indenter impact alone, which could result in more microscopic damage in the hard Rock. For the normal indenter and water jet impact velocities, the peak indenter stress could be reduced by more than 30%. As the distance between the indenter and water jet impact points increased from 0 to 12.5 mm, the peak indenter stress decreased accordingly from 71.6% to 14.7% compared with the indenter stress without water jet assistance, and it decreased with increasing distance. The influence rule of the bilateral water jets on Rock Breakage and indenter stress is analogous to the unilateral condition, but the enhanced degree of Breakage performance with bilateral water jets is better than that of the unilateral water jet. The inclined angle of the water jet also has an important effect on the Rock Breakage performance, and the inclined angle in the range of 80° ~ 90° is better for hard Rock Breakage. The allowable intersection angle between the impact directions of the water jet and indenter is important and significant for retaining the structural integrity of the indenter.
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Experimental Research on the Specific Energy Consumption of Rock Breakage Using Different Waterjet-Assisted Cutting Heads
Advances in Materials Science and Engineering, 2018Co-Authors: Hongxiang Jiang, Deguang MengAbstract:To investigate the specific energy consumption (SE) of Rock Breakage by cutting heads assisted by different types of waterjet and to identify optimal waterjet parameters and assistance types, Rock cutting with and without waterjets was carried on a Rock fragmentation test bed. SE is a comprehensive evaluation index and was developed according to the applied load on cutting head, and the SE under different cutting conditions was compared and analyzed. The results show that the SE of Rock Breakage without waterjet assistance increased with the increasing of Rock compressive strength (RCS) but that the limited drilling depth decreased. The effect of the waterjet pressure on the SE of Rock Breakage by the cutting head I was marked, and SE decreased by 30∼40% when the ratio between RCS and waterjet pressure was less than 1. However, the function of the waterjet assistance was poor; therefore, a ratio of 1 could be used to distinguish the Rock Breakage effect of cutting head I. For cutting head II, the Rock damage from the waterjet impact was limited due to the large waterjet standoff distance; thus the Rock Breakage performance of cutting head II was also limited. The waterjet impacting at the tip of the conical pick using cutting head III could enter into the cracks caused by the mechanical pick and fracture the Rock. Therefore, the Rock Breakage performance of cutting head III was better than that of cutting head II.
Hongxiang Jiang - One of the best experts on this subject based on the ideXlab platform.
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Experimental and Numerical Investigation of Hard Rock Breakage by Indenter Impact
Shock and Vibration, 2020Co-Authors: Hongxiang Jiang, Cai Zhiyuan, Wang Ouguo, Deguang MengAbstract:To investigate the effect of indenter shape, impact energy, and impact velocity on the Rock Breakage performance, a test device for Rock fragmentation by indenter impact was developed to obtain the Rock Breakage volume, depth, and area under different impact conditions. By comparing the Rock Breakage volume, depth, area, and specific energy consumption, the results show that indenter shape has a greater influence on the Rock Breakage performance than that of the impact velocity with the same impact energy, and impact energy plays a decisive role in Rock Breakage performance with an identical indenter shape and impact velocity. For the lowest to highest specific energy consumption, the order of indenter shape is cusp-conical, warhead, hemispherical, spherical-arc, and flat-top under the same impact energy and velocity, but the cusp-conical indenter is damaged after several impacts. The Rock Breakage volume, depth, and area all increase with the increase in impact energy, but the effect of the impact velocity could be ignored under the same impact energy. In addition, the Rock Breakage features of the numerical simulation and experiments are similar, which show that the crushing zone close to the indenter impact point is mainly caused by the high compressive stress, and then radial cracks are caused by the accumulative energy release. The findings of this study will contribute to progress in the performance and efficiency for percussive Rock drilling.
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Numerical investigation of hard Rock Breakage by high-pressure water jet assisted indenter impact using the coupled SPH/FEM method
Powder Technology, 2020Co-Authors: Hongxiang Jiang, Wang Ouguo, Zhao Huihe, Kuidong Gao, Wang Yongxin, Deguang MengAbstract:Abstract To investigate the effect of high-pressure water jet assistance on hard Rock Breakage by mechanical impact, a rate-dependent constitutive model was adopted to describe the mechanical behavior of the Rock. Then, a numerical model of Rock Breakage was developed using the coupled smoothed particle hydrodynamics (SPH) and finite element method (FEM). The indenter and Rock stress and Rock Breakage features were used to evaluate the assisted effect of the high-pressure water jet. The Rock stress perturbation by water jet assistance was more intense than that by indenter impact alone, which could result in more microscopic damage in the hard Rock. For the normal indenter and water jet impact velocities, the peak indenter stress could be reduced by more than 30%. As the distance between the indenter and water jet impact points increased from 0 to 12.5 mm, the peak indenter stress decreased accordingly from 71.6% to 14.7% compared with the indenter stress without water jet assistance, and it decreased with increasing distance. The influence rule of the bilateral water jets on Rock Breakage and indenter stress is analogous to the unilateral condition, but the enhanced degree of Breakage performance with bilateral water jets is better than that of the unilateral water jet. The inclined angle of the water jet also has an important effect on the Rock Breakage performance, and the inclined angle in the range of 80° ~ 90° is better for hard Rock Breakage. The allowable intersection angle between the impact directions of the water jet and indenter is important and significant for retaining the structural integrity of the indenter.
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Numerical study of hard Rock Breakage under indenter impact by the hybrid FDEM
Engineering Fracture Mechanics, 2020Co-Authors: Hongxiang Jiang, Zhiyuan Cai, Zhao HuiheAbstract:Abstract Achieving efficient crushing of hard Rocks has always been an urgent problem in mining and tunneling. A novel numerical model of Rock fragmentation was developed by the hybrid FDEM (finite and discrete element method) to investigate the mechanism of hard Rock Breakage produced by indenter impact. Zero-thickness discrete elements embedded into the finite model were used to describe the micromechanics of the Rock microscopic cementation via the mixed-mode cohesive traction response. The Breakage patterns could be well reproduced by the developed numerical model, which was consistent with the experimental results. The Rock Breakage features, such as impact crater, crushing zone, small debris, large fragments, symmetrical cracks and lateral cracks, were closely related to the variation in the contact force. The element deletion rate at the crushing stage was larger than that of the relatively stable stage and unloading stage, with the lowest rate of element deletion. The formation mechanisms of the crushing zone, small debris, large fragments, and symmetrical cracks were different. The crushing zone formation related to the cohesive element failure in shear action; the cohesive element failure for small debris formation was caused by the combination of tensile and shear action; the symmetrical and lateral crack formations were both caused by the tensile action on the failed cohesive element, but the tensile stress that produced the cohesive element failure in the lateral crack path was from the compression stress reflected in the boundary.
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Experimental Research on the Specific Energy Consumption of Rock Breakage Using Different Waterjet-Assisted Cutting Heads
Advances in Materials Science and Engineering, 2018Co-Authors: Hongxiang Jiang, Deguang MengAbstract:To investigate the specific energy consumption (SE) of Rock Breakage by cutting heads assisted by different types of waterjet and to identify optimal waterjet parameters and assistance types, Rock cutting with and without waterjets was carried on a Rock fragmentation test bed. SE is a comprehensive evaluation index and was developed according to the applied load on cutting head, and the SE under different cutting conditions was compared and analyzed. The results show that the SE of Rock Breakage without waterjet assistance increased with the increasing of Rock compressive strength (RCS) but that the limited drilling depth decreased. The effect of the waterjet pressure on the SE of Rock Breakage by the cutting head I was marked, and SE decreased by 30∼40% when the ratio between RCS and waterjet pressure was less than 1. However, the function of the waterjet assistance was poor; therefore, a ratio of 1 could be used to distinguish the Rock Breakage effect of cutting head I. For cutting head II, the Rock damage from the waterjet impact was limited due to the large waterjet standoff distance; thus the Rock Breakage performance of cutting head II was also limited. The waterjet impacting at the tip of the conical pick using cutting head III could enter into the cracks caused by the mechanical pick and fracture the Rock. Therefore, the Rock Breakage performance of cutting head III was better than that of cutting head II.
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Theoretical Modeling of Rock Breakage by Hydraulic and Mechanical Tool
Mathematical Problems in Engineering, 2014Co-Authors: Hongxiang Jiang, Songyong Liu, Liping WangAbstract:Rock Breakage by coupled mechanical and hydraulic action has been developed over the past several decades, but theoretical study on Rock fragmentation by mechanical tool with water pressure assistance was still lacking. The theoretical model of Rock Breakage by mechanical tool was developed based on the Rock fracture mechanics and the solution of Boussinesq’s problem, and it could explain the process of Rock fragmentation as well as predicating the peak reacting force. The theoretical model of Rock Breakage by coupled mechanical and hydraulic action was developed according to the superposition principle of intensity factors at the crack tip, and the reacting force of mechanical tool assisted by hydraulic action could be reduced obviously if the crack with a critical length could be produced by mechanical or hydraulic impact. The experimental results indicated that the peak reacting force could be reduced about 15% assisted by medium water pressure, and quick reduction of reacting force after peak value decreased the specific energy consumption of Rock fragmentation by mechanical tool. The crack formation by mechanical or hydraulic impact was the prerequisite to improvement of the ability of combined Breakage.
Ferri Hassani - One of the best experts on this subject based on the ideXlab platform.
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A REVIEW OF EXPLOSIVE-FREE Rock Breakage (EFRB) TECHNOLOGIES IN MINING INDUSTRY
2020Co-Authors: Ferri Hassani, Hamed Rafezi, Samir M DeyapAbstract:A REVIEW OF EXPLOSIVE-FREE Rock Breakage (EFRB) TECHNOLOGIES IN MINING INDUSTRY Abstract There are strategic drivers within the mining industry which are making explosive-free Rock Breakage approaches an option that is being reconsidered for the excavation of Rock masses. A comprehensive review of the performance and related aspects of explosive-free Rock breaking (EFRB) technologies is necessary to assess and demonstrate their applicability in the mining industry, particularly in continuous operations and autonomous mining. Additionally, it would facilitate a clear path of research and development. A comprehensive review of Rock Breakage technologies and expert projects would also provide sufficient understanding from available information and expert opinions of the advantages, limitations, and broad performance specifications of existing and promising EFRB methods for open pit and underground mining applications. The main EFRB technologies include mechanical cutting, microwave, laser, fluid, thermal and electrical applications. Finally, the application of microwave irradiation of Rocks has been conducted successfully in the laboratory as a high potential concept. The approach can be expanded to full-scale field implementation as a pre-conditioning tool to facilitate the mechanical breakdown of Rock in a continuous fashion as well as possible destressing of Rock under high stress. A reduction in mechanical strength of Rocks as a result of microwave irradiation could improve the performance of Rock excavation equipment such as a tunnel boring machine. This will be increasing the rate of penetration and reducing operation time. Keywords: Mining, Rock Breakage, Fragmentation, Explosive-free, Excavation
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Twenty years of experimental and numerical studies on microwave-assisted Breakage of Rocks and minerals-a review.
arXiv: Applied Physics, 2020Co-Authors: Khashayar Teimoori, Ferri HassaniAbstract:Microwaves have been used for a variety of applications in the past two decades. However, there has been a significant and growing interest in the applications of microwaves in hard Rock Breakage and mineral processing industries. The purpose of this review paper is to focus on these applications and to present a careful review of the state-of-the-art experimental and numerical modeling techniques introduced in the literature from 2000 to 2020. The challenges involved in this research area are surveyed, and the efforts that should be made regarding the potential practical implementation of microwaves in industry are discussed.
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Experimental Investigations of Microwave Effects on Rock Breakage Using SEM Analysis
Proceedings 17th International Conference on Microwave and High Frequency Heating, 2019Co-Authors: Khashayar Teimoori, Ferri Hassani, Agus P. Sasmito, Ali MadisehAbstract:Financial support for this work from the Natural Sciences and Engineering Research Council of Canada (NSERC), De Beers Group, Argex, Metso and the McGill Engineering Doctoral Award (MEDA) Award is gratefully acknowledged.
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Numerical investigation on the effects of single-mode microwave treatment on Rock Breakage system
Proceedings 17th International Conference on Microwave and High Frequency Heating, 2019Co-Authors: Khashayar Teimoori, Ferri Hassani, Agus P. Sasmito, Ali MadisehAbstract:Financial support for this work from the Natural Sciences and Engineering Research Council (NSERC) of Canada, the McGill Engineering Doctoral Award (MEDA) Award is gratefully acknowledged.
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Experimental Investigation on the Effects of Microwave Treatment on Basalt Heating, Mechanical Strength, and Fragmentation
Rock Mechanics and Rock Engineering, 2019Co-Authors: Lu Gaoming, Ferri Hassani, Xia-ting Feng, Li Yuanhui, Xiwei ZhangAbstract:Microwave energy can be used to assist mechanical Rock Breakage for civil and mining engineering operations. To assess the industrial applicability of this technology, microwave heating of basalt specimens in a multi-mode cavity (a microwave chamber) at different power levels was followed by conventional mechanical strength and fragmentation effect tests in the laboratory. X-ray diffraction and scanning electron microscopy/energy-dispersive X-ray spectroscopy were used to determine the mineral composition and distribution of the basalt, to aid interpretation of crack propagation patterns and the associated strength reduction mechanism. These analyses demonstrated that cracks mainly occurred around olivine grains, primarily as intergranular cracks between olivine and plagioclase grains and intragranular cracks within olivine grains. Strength reduction during microwave fracturing of basalt is driven by heat from enstatite (a microwave-sensitive mineral) and volumetric expansion of olivine (a thermally expansive mineral). Uniaxial compressive, Brazilian tensile, and point load strengths all decreased with increasing microwave irradiation time at rates that were positively related to the power level. For a given power level, mechanical strength reduction can be estimated from linear relationships with irradiation time. On the other hand, a power function best described burst time (the irradiation time at which the specimen burst into fragments) vs. power level (for a given specimen size) and burst time vs. specimen size (for a given power level) relationships. Microwave-induced hard Rock fracturing can be an integral part of new methods for Rock Breakage and tunnel excavation.
Ting Ren - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the Stress Wave Effect During Rock Breakage by Pulsating Jets
Rock Mechanics and Rock Engineering, 2015Co-Authors: Yong Liu, Jianping Wei, Ting RenAbstract:Formation, propagation and attenuation of stress waves during Rock Breakage by pulsating jets are simulated by introducing the Johnson–Holmquist-Concrete nonlinear constitutive model, and using the smoothed particle hydrodynamics approach. The curve of stress over time at different locations of the Rock surface under the action of high-velocity pulsating jets is obtained, as well as relationship curve between amplitude of stress wave and distance to jet action spot. Based on the computational results, Breakage behavior of Rocks under stress wave effect, and impacts of jet velocity and Rock properties on stress wave effect are analyzed. The results show that the stress wave effect of pulsating jets is rather strongly localized, and the amplitude of stress wave decreases sharply with increasing distance to jet action spot. The intensity and effect range of stress wave are in direct proportion to jet velocity; besides, there is a threshold velocity regarding macroscopic failure of Rocks. Rocks of different lithologies have somewhat different failure modes under stress wave action of pulsating jets; failure mode of low strength Rocks like sandstone is mainly crack propagation under tensile stress during Rock loading and unloading processes, whereas the failure mode of hard brittle Rocks such as limestone and granite is mainly longitudinal failure caused by stress concentration.
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Experimental study of flow field structure of interrupted pulsed water jet and Breakage of hard Rock
International Journal of Rock Mechanics and Mining Sciences, 2015Co-Authors: Yong Liu, Jianping Wei, Ting RenAbstract:Abstract Interrupted pulsed water jet has great potential for application in hard Rock Breakage as it can be easily generated and controlled. The sharp nature of the head and tail of the jet significantly influences on water hammer pressure of the jet and efficiency of hard Rock Breakage. In this paper, the evolution of a single pulse was captured using high-speed photography and analyzed by numerical simulation. It was found that the velocity of the jet head was slower than the jet velocity at the nozzle exit, but the former still had high turbulent kinetic energy. A U-shaped structure was formed after the jet head made contact with the target, and it in turn affects the peak and duration of the water hammer pressure, as well as its distribution on target. The effect of stress wave propagation on Rock Breakage during erosion of granite by interrupted pulsed water jet was investigated by ultrasonic testing. Results showed that there were two modes of Rock Breakage, namely macroscopic fracture of Rock blocks, and fixed-depth erosion hole formation. These were caused by the combined effects of the impact stress wave and the pulsating water wedge pressure. The effects of jet diameter, pulsation frequency and jet power on erosion rate and specific erosion energy were analyzed.
Dongya Han - One of the best experts on this subject based on the ideXlab platform.
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Sequential Indentation Tests to Investigate the Influence of Confining Stress on Rock Breakage by Tunnel Boring Machine Cutter in a Biaxial State
Rock Mechanics and Rock Engineering, 2015Co-Authors: Jie Liu, Ping Cao, Dongya HanAbstract:The influence of confining stress on Rock Breakage by a tunnel boring machine cutter was investigated by conducting sequential indentation tests in a biaxial state. Combined with morphology measurements of breaking grooves and an analysis of surface and internal crack propagation between nicks, the effects of maximum confining stress and minimum stress on indentation efficiency, crack propagation and chip formation were investigated. Indentation tests and morphology measurements show that increasing a maximum confining stress will result in increased consumed energy in indentations, enlarged groove volumes and promoted indentation efficiency when the corresponding minimum confining stress is fixed. The energy consumed in indentations will increase with increase in minimum confining stress, however, because of the decreased groove volumes as the minimum confining stress increases, the efficiency will decrease. Observations of surface crack propagation show that more intensive fractures will be induced as the maximum confining stress increases, whereas the opposite occurs for an increase of minimum confining stress. An observation of the middle section, cracks and chips shows that as the maximum confining stress increases, chips tend to form in deeper parts when the minimum confining stress is fixed, whereas they tend to formed in shallower parts as the minimum confining stress increases when the maximum confining stress is fixed.
