Demand is growing for explosive-free rock breakage systems for civil and mining engineering, and space industry applications. This paper highlights the work being undertaken in the Geomechanics Laboratory of Mc Gill U...Demand is growing for explosive-free rock breakage systems for civil and mining engineering, and space industry applications. This paper highlights the work being undertaken in the Geomechanics Laboratory of Mc Gill University to make a real application of microwave-assisted mechanical rock breakage to fullface tunneling machines and drilling. Comprehensive laboratory tests investigated the effect of microwave radiation on temperature profiles and strength reduction in hard rocks(norite, granite, and basalt)for a range of exposure times and microwave power levels. The heating rate on the surface of the rock specimens linearly decreased with distance between the sample and the microwave antenna, regardless of microwave power level and exposure time. Tensile and uniaxial compressive strengths were reduced with increasing exposure time and power level. Scanning electron micrographs(SEMs) highlighted fracture development in treated basalt. It was concluded that the microwave power level has a strong positive influence on the amount of heat damage induced to the rock surface. Numerical simulations of electric field intensity and wave propagation conducted with COMSOL Multiphysics~ software generated temperature profiles that were in close agreement with experimental results.展开更多
This paper examines the stability condition of a jointed rock slope in the south western region of Saudi Arabia using deterministic and probabilistic approaches,under both dry and wet conditions.The study area is char...This paper examines the stability condition of a jointed rock slope in the south western region of Saudi Arabia using deterministic and probabilistic approaches,under both dry and wet conditions.The study area is characterized by complex geology in rugged terrains.The stability analysis is carried out using the code FLAC3D to generate a 3-dimensional,ubiquitous joint model,to determine the influence of the dominant,unfavourable discontinuity orientation with respect to the slope face.The deterministic analysis is first implemented using the mean values of the selected random variables,namely the dip,dip direction and friction angle of the dominant discontinuity set,and the stability condition is assessed with a factor of safety based on the classical frictional joint constitutive model.A Box-Behnken design(BBD)approach is then adopted to create the surface response function as a second order polynomial for the factor of safety.To do so,fifteen FLAC3D models are generated in accordance with the BBD.Based on this,10,000 simulations of different slope realizations are carried out using Monte-Carlo simulation technique,and the probability of unsatisfactory of performance of the rock slope is assessed.It is shown that the probabilistic approach provides more insight and confidence in the stability condition of the rock slope,both under dry and steady state heavy rainfall conditions.A discussion is presented on the significance of accepting lower safety factors when heavy rainfall conditions are encountered.展开更多
The method of drilling and blasting with explosives is widely used in rock fragmentation applications in the mining industry for mine development and ore production.However,the use of explosives is associated with rig...The method of drilling and blasting with explosives is widely used in rock fragmentation applications in the mining industry for mine development and ore production.However,the use of explosives is associated with rigorous safety and environmental constraints as blasting creates toxic fumes,ground vibrations,and dust.This study is focused on the use of Soundless Chemical Demolition Agents(SCDA)as a more environmentally friendly method for rock breakage and a potential replacement of explosives.In this paper,the results of a series of experimental tests are reported to identify the efect of SCDA on hard rock breakage under no load and under uniaxial loading conditions.Stanstead granite prismatic specimens of 152.4 mm(6″)×152.4–203.2 mm(6–8″)×406.4 mm(16″)are used to test the infuence of borehole size on the time to fracturing with SCDA borehole size of 25.4 mm(1″),31.75 mm(1.25″)and 38.1 mm(1.5″).It is shown that the fracturing time decreases with increasing borehole size.It is also shown that specimens subjected to uniaxial compression of 5 MPa fracture as early as 7 h after SCDA mixing.A borehole spacing to borehole diameter ratio of 12.8 to 14.6 is suggested for practical applications.展开更多
This study investigates the technique of variational calculus applied to estimate the slope stability considering the mechanism of planar failure.The critical plane failure surface should be determined because it theo...This study investigates the technique of variational calculus applied to estimate the slope stability considering the mechanism of planar failure.The critical plane failure surface should be determined because it theoretically indicates the most unfavorable plane to be considered when stabilizing a slope to rectify the instability generated by several statistically possible planes.This generates integrals that can be solved by numerical methods,such as the Newton Cotes and the finite differences methods.Additionally,a system of nonlinear equations is obtained and solved.The surface of the critical planar failure is determined by applying the condition of transversality in mobile boundaries,for which various examples are provided.The number of slices is varied in one of the examples,while the surface of the critical planar failure is determined in the others.Results are compared using analytical methods through axis rotations.All the results obtained by considering normal stress,safety factors,and critical planar failure are nearly the same;however,in this research,a study is carried out for“n”number of slices using programming methods.Sub-routines are important because they can be applied in slopes with different geometry,surcharge,interstitial pressure,and pseudo-static load.展开更多
基金the Natural Sciences and Engineering Research Council of Canada(NSERC)with the collaboration of IAMGold,Glencore,and Vale Canada,who generously contributed financially to this research project
文摘Demand is growing for explosive-free rock breakage systems for civil and mining engineering, and space industry applications. This paper highlights the work being undertaken in the Geomechanics Laboratory of Mc Gill University to make a real application of microwave-assisted mechanical rock breakage to fullface tunneling machines and drilling. Comprehensive laboratory tests investigated the effect of microwave radiation on temperature profiles and strength reduction in hard rocks(norite, granite, and basalt)for a range of exposure times and microwave power levels. The heating rate on the surface of the rock specimens linearly decreased with distance between the sample and the microwave antenna, regardless of microwave power level and exposure time. Tensile and uniaxial compressive strengths were reduced with increasing exposure time and power level. Scanning electron micrographs(SEMs) highlighted fracture development in treated basalt. It was concluded that the microwave power level has a strong positive influence on the amount of heat damage induced to the rock surface. Numerical simulations of electric field intensity and wave propagation conducted with COMSOL Multiphysics~ software generated temperature profiles that were in close agreement with experimental results.
基金financially supported by the Saudi Geological Survey through a doctoral fellowship at McGill University
文摘This paper examines the stability condition of a jointed rock slope in the south western region of Saudi Arabia using deterministic and probabilistic approaches,under both dry and wet conditions.The study area is characterized by complex geology in rugged terrains.The stability analysis is carried out using the code FLAC3D to generate a 3-dimensional,ubiquitous joint model,to determine the influence of the dominant,unfavourable discontinuity orientation with respect to the slope face.The deterministic analysis is first implemented using the mean values of the selected random variables,namely the dip,dip direction and friction angle of the dominant discontinuity set,and the stability condition is assessed with a factor of safety based on the classical frictional joint constitutive model.A Box-Behnken design(BBD)approach is then adopted to create the surface response function as a second order polynomial for the factor of safety.To do so,fifteen FLAC3D models are generated in accordance with the BBD.Based on this,10,000 simulations of different slope realizations are carried out using Monte-Carlo simulation technique,and the probability of unsatisfactory of performance of the rock slope is assessed.It is shown that the probabilistic approach provides more insight and confidence in the stability condition of the rock slope,both under dry and steady state heavy rainfall conditions.A discussion is presented on the significance of accepting lower safety factors when heavy rainfall conditions are encountered.
基金supported by a research grant from Natural Resources Canada,Clean Growth Program,Grant No.CGP-17-1003 and industry partner Newmont Corporation。
文摘The method of drilling and blasting with explosives is widely used in rock fragmentation applications in the mining industry for mine development and ore production.However,the use of explosives is associated with rigorous safety and environmental constraints as blasting creates toxic fumes,ground vibrations,and dust.This study is focused on the use of Soundless Chemical Demolition Agents(SCDA)as a more environmentally friendly method for rock breakage and a potential replacement of explosives.In this paper,the results of a series of experimental tests are reported to identify the efect of SCDA on hard rock breakage under no load and under uniaxial loading conditions.Stanstead granite prismatic specimens of 152.4 mm(6″)×152.4–203.2 mm(6–8″)×406.4 mm(16″)are used to test the infuence of borehole size on the time to fracturing with SCDA borehole size of 25.4 mm(1″),31.75 mm(1.25″)and 38.1 mm(1.5″).It is shown that the fracturing time decreases with increasing borehole size.It is also shown that specimens subjected to uniaxial compression of 5 MPa fracture as early as 7 h after SCDA mixing.A borehole spacing to borehole diameter ratio of 12.8 to 14.6 is suggested for practical applications.
文摘This study investigates the technique of variational calculus applied to estimate the slope stability considering the mechanism of planar failure.The critical plane failure surface should be determined because it theoretically indicates the most unfavorable plane to be considered when stabilizing a slope to rectify the instability generated by several statistically possible planes.This generates integrals that can be solved by numerical methods,such as the Newton Cotes and the finite differences methods.Additionally,a system of nonlinear equations is obtained and solved.The surface of the critical planar failure is determined by applying the condition of transversality in mobile boundaries,for which various examples are provided.The number of slices is varied in one of the examples,while the surface of the critical planar failure is determined in the others.Results are compared using analytical methods through axis rotations.All the results obtained by considering normal stress,safety factors,and critical planar failure are nearly the same;however,in this research,a study is carried out for“n”number of slices using programming methods.Sub-routines are important because they can be applied in slopes with different geometry,surcharge,interstitial pressure,and pseudo-static load.
