Strainburst is the most frequently encountered type of rockburst in underground mines.Strainburst occurs when the stress near the excavation boundary reaches the peak strength of the rock mass causing it to fail sudde...Strainburst is the most frequently encountered type of rockburst in underground mines.Strainburst occurs when the stress near the excavation boundary reaches the peak strength of the rock mass causing it to fail suddenly and violently.To mitigate strainburst damage risk,effective rock support is needed.In strainburst-prone grounds,it is critical to have rock support components to fulfill the role of rock reinforcement first to prevent rock failure.On the other hand,well-retained and reinforced rock masses may be excessively deformed and fail violently.In such a case,yielding elements are needed in the rock support system to absorb the excess strain energy released due to rock failure.The conventional method to support strainburst-prone grounds is to install rock reinforcement system using rebar and mesh first and then install yielding support system using dynamic rockbolts at a later stage.This two-stage rock support installation process is not effective because it can adversely impact mine production schedule.This paper presents a new,patented dynamic rockbolt,which is called superbolt and is developed for rock support in burst-prone grounds.Laboratory testing confirmed that the superbolt has superb capacity to achieve the goal of reinforcing and holding rock masses.The superbolt is characterized by high dynamic energy absorption capacity,consistent performance,and the ability to withstand repeated dynamic loading.The new rockbolt can be used in a one-pass rock support system to facilitate rapid drift development in underground mines and increase mine safety and productivity.展开更多
The presence of geological structures such as faults, joints, and dykes has been observed near excavation boundaries in many rockburst case histories. In this paper, the role of discontinuities around tunnels in rockb...The presence of geological structures such as faults, joints, and dykes has been observed near excavation boundaries in many rockburst case histories. In this paper, the role of discontinuities around tunnels in rockburst occurrence was studied. For this purpose, the Abaqus explicit code was used to simulate dynamic rock failure in deep tunnels. Material heterogeneity was considered using Python scripting in Abaqus. Rockbursts near fault regions in deep tunnels under static and dynamic loads were studied.Several tunnel models with and without faults were built and static and dynamic loads were used to simulate rock failure. The velocity and the released kinetic energy of failed rocks, the failure zone around the tunnel, and the deformed mesh were studied to identify stable and unstable rock failures. Compared with models without discontinuities, the results showed that the velocity and the released kinetic energy of failed rocks were higher, the failure zone around the tunnel was larger, and the mesh was more deformed in the models with discontinuities, indicating that rock failure in the models with discontinuities was more violent. The modeling results confirm that the presence of geological structures in the vicinity of deep excavations could be one of the major influence factors for the occurrence of rockburst. It can explain localized rockburst occurrence in civil tunnels and mining drifts. The presented methodology in this paper for rockburst analysis can be useful for rockburst anticipation and control during mining and tunneling in highly stressed ground.展开更多
Discontinuity waviness is one of the most important properties that influence shear strength of jointed rock masses,and it should be incorporated into numerical models for slope stability assessment.However,in most ex...Discontinuity waviness is one of the most important properties that influence shear strength of jointed rock masses,and it should be incorporated into numerical models for slope stability assessment.However,in most existing numerical modeling tools,discontinuities are often simplified into planar surfaces.Discrete fracture network modeling tools such as MoFrac allow the simulation of non-planar discontinuities which can be incorporated into lattice-spring-based geomechanical software such as Slope Model for slope stability assessment.In this study,the slope failure of the south wall at Cadia Hill open pit mine is simulated using the lattice-spring-based synthetic rock mass(LS-SRM)modeling approach.First,the slope model is calibrated using field displacement monitoring data,and then the influence of different discontinuity configurations on the stability of the slope is investigated.The modeling results show that the slope with non-planar discontinuities is comparatively more stable than the ones with planar discontinuities.In addition,the slope becomes increasingly unstable with the increases of discontinuity intensity and size.At greater pit depth with higher in situ stress,both the slope models with planar and non-planar discontinuities experience localized failures due to very high stress concentrations,and the slope model with planar discontinuities is more deformable and less stable than that with non-planar discontinuities.展开更多
Cooling energy needs, for mines in Northern Ontario, are mainly driven by the mining depth and its operation. Part I of this research focusses on the thermal energy loads in deep mines as a result of the virgin rock t...Cooling energy needs, for mines in Northern Ontario, are mainly driven by the mining depth and its operation. Part I of this research focusses on the thermal energy loads in deep mines as a result of the virgin rock temperature, mining operations and climatic conditions. A breakdown of the various heat sources is outlined, for an underground mine producing 3500 tonnes per day of broken rock, taking into consideration the latent and sensible portions of that heat to properly assess the wet bulb global temperature. The resulting thermal loads indicate that cooling efforts would be needed both at surface and underground to maintain the temperature underground within the legal threshold. In winter the air might also have to be heated at surface and cooled underground, to ensure that icing does not occur in the inlet ventilation shaft-the main reason why coolin~ cannot be focussed solely at surface.展开更多
Ventilation has always been an integral part of underground mining operations.As surface and shallow deposits are depleting,extracting ores from deeper underground levels is becoming more and more common,and is expect...Ventilation has always been an integral part of underground mining operations.As surface and shallow deposits are depleting,extracting ores from deeper underground levels is becoming more and more common,and is expected to grow in the future[1].Rising environmental awareness,energy cost and implementation of carbon tax in some countries have led the mining industry to look for cleaner alternatives[2].展开更多
Cooling energy needs, for mines in Northern Ontario, are mainly driven by the mining cooling technologies available and the cost to implement them in a 2500 m deep underground mine. The cooling technologies reviewed h...Cooling energy needs, for mines in Northern Ontario, are mainly driven by the mining cooling technologies available and the cost to implement them in a 2500 m deep underground mine. The cooling technologies reviewed herein include mechanical and natural cooling systems, ranging from mechanical chillers to seasonal thermal storages. The economic and operating parameters for each technology were estimated and evaluated according to the mine's energy loads. Including consideration of any combined heat and power benefits of the technology, cooling tower requirements, etc., the resulting cost of implementation for each technology could be ranked. This showed that the natural thermal storage systems and conventional chillers were the most cost-effective, mainly since the natural systems had very low operating cost and the chillers had relatively low capital costs.展开更多
基金financial support from NSERC(No.CRDPJ 461108-13)Mansour Mining Technologies Inc.(MMTI)
文摘Strainburst is the most frequently encountered type of rockburst in underground mines.Strainburst occurs when the stress near the excavation boundary reaches the peak strength of the rock mass causing it to fail suddenly and violently.To mitigate strainburst damage risk,effective rock support is needed.In strainburst-prone grounds,it is critical to have rock support components to fulfill the role of rock reinforcement first to prevent rock failure.On the other hand,well-retained and reinforced rock masses may be excessively deformed and fail violently.In such a case,yielding elements are needed in the rock support system to absorb the excess strain energy released due to rock failure.The conventional method to support strainburst-prone grounds is to install rock reinforcement system using rebar and mesh first and then install yielding support system using dynamic rockbolts at a later stage.This two-stage rock support installation process is not effective because it can adversely impact mine production schedule.This paper presents a new,patented dynamic rockbolt,which is called superbolt and is developed for rock support in burst-prone grounds.Laboratory testing confirmed that the superbolt has superb capacity to achieve the goal of reinforcing and holding rock masses.The superbolt is characterized by high dynamic energy absorption capacity,consistent performance,and the ability to withstand repeated dynamic loading.The new rockbolt can be used in a one-pass rock support system to facilitate rapid drift development in underground mines and increase mine safety and productivity.
基金Financial supports from the Natural Sciences and Engineering Research Council(NSERC)of Canada(CRDPJ 418932-11)Vale,LKAB,CEMI,MIRARCO,and the Open Research Fund of the State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(Grant No.Z015001)for this work are gratefully acknowledged
文摘The presence of geological structures such as faults, joints, and dykes has been observed near excavation boundaries in many rockburst case histories. In this paper, the role of discontinuities around tunnels in rockburst occurrence was studied. For this purpose, the Abaqus explicit code was used to simulate dynamic rock failure in deep tunnels. Material heterogeneity was considered using Python scripting in Abaqus. Rockbursts near fault regions in deep tunnels under static and dynamic loads were studied.Several tunnel models with and without faults were built and static and dynamic loads were used to simulate rock failure. The velocity and the released kinetic energy of failed rocks, the failure zone around the tunnel, and the deformed mesh were studied to identify stable and unstable rock failures. Compared with models without discontinuities, the results showed that the velocity and the released kinetic energy of failed rocks were higher, the failure zone around the tunnel was larger, and the mesh was more deformed in the models with discontinuities, indicating that rock failure in the models with discontinuities was more violent. The modeling results confirm that the presence of geological structures in the vicinity of deep excavations could be one of the major influence factors for the occurrence of rockburst. It can explain localized rockburst occurrence in civil tunnels and mining drifts. The presented methodology in this paper for rockburst analysis can be useful for rockburst anticipation and control during mining and tunneling in highly stressed ground.
基金Ontario Trillium Scholarship for supporting the doctorate program at Laurentian UniversityFinancial supports from the Natural Sciences and Engineering Research Council of Canada(NSERC CRD 470490-14)of Canada+1 种基金Nuclear Waste Management Organization(NWMO)Rio Tinto。
文摘Discontinuity waviness is one of the most important properties that influence shear strength of jointed rock masses,and it should be incorporated into numerical models for slope stability assessment.However,in most existing numerical modeling tools,discontinuities are often simplified into planar surfaces.Discrete fracture network modeling tools such as MoFrac allow the simulation of non-planar discontinuities which can be incorporated into lattice-spring-based geomechanical software such as Slope Model for slope stability assessment.In this study,the slope failure of the south wall at Cadia Hill open pit mine is simulated using the lattice-spring-based synthetic rock mass(LS-SRM)modeling approach.First,the slope model is calibrated using field displacement monitoring data,and then the influence of different discontinuity configurations on the stability of the slope is investigated.The modeling results show that the slope with non-planar discontinuities is comparatively more stable than the ones with planar discontinuities.In addition,the slope becomes increasingly unstable with the increases of discontinuity intensity and size.At greater pit depth with higher in situ stress,both the slope models with planar and non-planar discontinuities experience localized failures due to very high stress concentrations,and the slope model with planar discontinuities is more deformable and less stable than that with non-planar discontinuities.
基金CEMI (Centre for Excellence in Mining Innovation) for their funding to support this research
文摘Cooling energy needs, for mines in Northern Ontario, are mainly driven by the mining depth and its operation. Part I of this research focusses on the thermal energy loads in deep mines as a result of the virgin rock temperature, mining operations and climatic conditions. A breakdown of the various heat sources is outlined, for an underground mine producing 3500 tonnes per day of broken rock, taking into consideration the latent and sensible portions of that heat to properly assess the wet bulb global temperature. The resulting thermal loads indicate that cooling efforts would be needed both at surface and underground to maintain the temperature underground within the legal threshold. In winter the air might also have to be heated at surface and cooled underground, to ensure that icing does not occur in the inlet ventilation shaft-the main reason why coolin~ cannot be focussed solely at surface.
文摘Ventilation has always been an integral part of underground mining operations.As surface and shallow deposits are depleting,extracting ores from deeper underground levels is becoming more and more common,and is expected to grow in the future[1].Rising environmental awareness,energy cost and implementation of carbon tax in some countries have led the mining industry to look for cleaner alternatives[2].
基金CEMI (Centre for Excellence in Mining Innovation) for their funding to support this research
文摘Cooling energy needs, for mines in Northern Ontario, are mainly driven by the mining cooling technologies available and the cost to implement them in a 2500 m deep underground mine. The cooling technologies reviewed herein include mechanical and natural cooling systems, ranging from mechanical chillers to seasonal thermal storages. The economic and operating parameters for each technology were estimated and evaluated according to the mine's energy loads. Including consideration of any combined heat and power benefits of the technology, cooling tower requirements, etc., the resulting cost of implementation for each technology could be ranked. This showed that the natural thermal storage systems and conventional chillers were the most cost-effective, mainly since the natural systems had very low operating cost and the chillers had relatively low capital costs.
