An increased global supply of minerals is essential to meet the needs and expectations of a rapidly rising world population. This implies extraction from greater depths. Autonomous mining systems, developed through su...An increased global supply of minerals is essential to meet the needs and expectations of a rapidly rising world population. This implies extraction from greater depths. Autonomous mining systems, developed through sustained R＆D by equipment suppliers, reduce miner exposure to hostile work environments and increase safety. This places increased focus on ＂ground control＂ and on rock mechanics to define the depth to which minerals may be extracted economically. Although significant efforts have been made since the end of World War II to apply mechanics to mine design, there have been both technological and organizational obstacles. Rock in situ is a more complex engineering material than is typically encountered in most other engineering disciplines. Mining engineering has relied heavily on empirical procedures in design for thousands of years. These are no longer adequate to address the challenges of the 21st century, as mines venture to increasingly greater depths. The development of the synthetic rock mass （SRM） in 2008 provides researchers with the ability to analyze the deformational behavior of rock masses that are anisotropic and discontinuous-attributes that were described as the defining characteristics of in situ rock by Leopold Mfiller, the president and founder of the International Society for Rock Mechanics （ISRM）, in 1966. Recent developments in the numerical modeling of large-scale mining operations （e.g., caving） using the SRM reveal unanticipated deformational behavior of the rock. The application of massive parallelization and cloud computational techniques offers major opportunities： for example, to assess uncertainties in numerical predictions： to establish the mechanics basis for the empirical rules now used in rock engineering and their validity for the prediction of rock mass behavior beyond current experience： and to use the discrete element method （DEM） in the optimization of deep mine design. For the first time, mining-and rock engineering-will have its own mech展开更多
The post-peak characteristics of coal serve as a direct reflection of its failure process and are essential parameters for evaluating brittleness and bursting liability.Understanding the significant factors that influ...The post-peak characteristics of coal serve as a direct reflection of its failure process and are essential parameters for evaluating brittleness and bursting liability.Understanding the significant factors that influence post-peak characteristics can offer valuable insights for the prevention of coal bursts.In this study,the Synthetic Rock Mass method is employed to establish a numerical model,and the factors affecting coal post-peak characteristics are analyzed from four perspectives:coal matrix mechanical parameters,structural weak surface properties,height-to-width ratio,and loading rate.The research identifies four significant influencing factors:deformation modulus,density of discrete fracture networks,height-to-width ratio,and loading rate.The response and sensitivity of post-peak characteristics to single-factor and multi-factor interactions are assessed.The result suggested that feasible prevention and control measures for coal bursts can be formulated through four approaches:weakening the mechanical properties of coal pillars,increasing the number of structural weak surfaces in coal pillars,reducing the width of coal pillars,and optimizing mining and excavation speed.The efficacy of measures aimed at weakening the mechanical properties of coal is successfully demonstrated through a case study on coal burst prevention using large-diameter borehole drilling.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
Accurate estimation of the triaxial compression behavior of jointed coal is essential for coal mining.Few studies addressed the triaxial compression behavior of large-scale rock mass,especially with real joint geometr...Accurate estimation of the triaxial compression behavior of jointed coal is essential for coal mining.Few studies addressed the triaxial compression behavior of large-scale rock mass,especially with real joint geometry.We employed a numerical synthetic rock mass(SRM)method to study the triaxial compression behavior of jointed coal.Jointed-coal specimens were constructed based on in-situ joint measurements and microparameter calibration against laboratory experiments.A series of triaxial compression tests under different loading orientations and confining pressures were numerically performed to obtain joint and confining-pressure effects on the triaxial compression behavior and reveal the failure mechanism of jointed coal.Results suggest that the triaxial compression behavior of the jointed coal has strong joint and confining-pressure effects.Joints weaken the strength and elastic modulus,reduce the lateral deformation,and affect the geometries of the shear-rupture surface.An increase in the confining pressure causes the peak and residual strength increase significantly.With an increase in the confining pressure,the elastic modulus increases sharply at low confining pressure,the mechanical behavior transitions from brittleness to ductility,the failure mode transitions from shear-rupture surface to plastic flow,and the joint effect diminishes and even disappears.The jointed coal fails by means of a shear-rupture surface under triaxial compression loading with a confining pressure(which is not too high),and the geometries of the shear-rupture surface vary with the distribution of joints.展开更多
The main objective of this paper is to examine the influence of the applied confining stress on the rock mass modulus of moderately jointed rocks（well interlocked undisturbed rock mass with blocks formed by three or ...The main objective of this paper is to examine the influence of the applied confining stress on the rock mass modulus of moderately jointed rocks（well interlocked undisturbed rock mass with blocks formed by three or less intersecting joints）. A synthetic rock mass modelling（SRM） approach is employed to determine the mechanical properties of the rock mass. In this approach, the intact body of rock is represented by the discrete element method（DEM）-Voronoi grains with the ability of simulating the initiation and propagation of microcracks within the intact part of the model. The geometry of the preexisting joints is generated by employing discrete fracture network（DFN） modelling based on field joint data collected from the Brockville Tunnel using LiDAR scanning. The geometrical characteristics of the simulated joints at a representative sample size are first validated against the field data, and then used to measure the rock quality designation（RQD）, joint spacing, areal fracture intensity（P21）, and block volumes. These geometrical quantities are used to quantitatively determine a representative range of the geological strength index（GSI）. The results show that estimating the GSI using the RQD tends to make a closer estimate of the degree of blockiness that leads to GSI values corresponding to those obtained from direct visual observations of the rock mass conditions in the field. The use of joint spacing and block volume in order to quantify the GSI value range for the studied rock mass suggests a lower range compared to that evaluated in situ. Based on numerical modelling results and laboratory data of rock testing reported in the literature, a semi-empirical equation is proposed that relates the rock mass modulus to confinement as a function of the areal fracture intensity and joint stiffness.展开更多
裂隙岩质高边坡稳定性的变形破坏模式实际上取决于其岩体结构特征所控制的潜在路径形式。在复杂裂隙岩体结构边坡中,不同类型和规模的陡缓结构面交切组合将其破坏路径更加不确定化。复合岩体技术(synthetic rock mass,SRM)可有效实现受...裂隙岩质高边坡稳定性的变形破坏模式实际上取决于其岩体结构特征所控制的潜在路径形式。在复杂裂隙岩体结构边坡中,不同类型和规模的陡缓结构面交切组合将其破坏路径更加不确定化。复合岩体技术(synthetic rock mass,SRM)可有效实现受结构控制的滑移破坏。遵循该理念指导,以西南某水电工程复杂裂隙岩质高边坡为例,采用颗粒离散元PFC软件平台研发的SRM技术,解决了利用均质区划分为基础的非均匀分布的规模不同的陡缓结构面复杂网络模型构建、考虑颗粒尺寸效应范围的不同工程地质性状岩石材料模型构建、以及结合重度增加法计算复合岩体模拟裂隙岩质高边坡潜在失稳路径的技术难题,收效颇丰。模拟结果表明:该边坡潜在失稳的主要路径为陡倾的断层、岩脉与倾向坡外的长大中缓倾角裂隙组合形成阶梯状形式,其潜在失稳路径以浅表局部的剪切–拉张失稳模式为主,为该工程后续的边坡设计提供了可靠的边界范围和指导意义。本项研究方法和结论具有可观的推广价值和普适性。展开更多
文摘An increased global supply of minerals is essential to meet the needs and expectations of a rapidly rising world population. This implies extraction from greater depths. Autonomous mining systems, developed through sustained R＆D by equipment suppliers, reduce miner exposure to hostile work environments and increase safety. This places increased focus on ＂ground control＂ and on rock mechanics to define the depth to which minerals may be extracted economically. Although significant efforts have been made since the end of World War II to apply mechanics to mine design, there have been both technological and organizational obstacles. Rock in situ is a more complex engineering material than is typically encountered in most other engineering disciplines. Mining engineering has relied heavily on empirical procedures in design for thousands of years. These are no longer adequate to address the challenges of the 21st century, as mines venture to increasingly greater depths. The development of the synthetic rock mass （SRM） in 2008 provides researchers with the ability to analyze the deformational behavior of rock masses that are anisotropic and discontinuous-attributes that were described as the defining characteristics of in situ rock by Leopold Mfiller, the president and founder of the International Society for Rock Mechanics （ISRM）, in 1966. Recent developments in the numerical modeling of large-scale mining operations （e.g., caving） using the SRM reveal unanticipated deformational behavior of the rock. The application of massive parallelization and cloud computational techniques offers major opportunities： for example, to assess uncertainties in numerical predictions： to establish the mechanics basis for the empirical rules now used in rock engineering and their validity for the prediction of rock mass behavior beyond current experience： and to use the discrete element method （DEM） in the optimization of deep mine design. For the first time, mining-and rock engineering-will have its own mech
基金National NaturalScience Foundation of China(52074151,52274085,52274123)Tiandi Science and Technology Co.,Ltd.Science and Technology Innovation Venture Capital Special Project(TDKC-2022-MS-01,TDKC-2022-QN-01,TDKC-2022-QN-02).
文摘The post-peak characteristics of coal serve as a direct reflection of its failure process and are essential parameters for evaluating brittleness and bursting liability.Understanding the significant factors that influence post-peak characteristics can offer valuable insights for the prevention of coal bursts.In this study,the Synthetic Rock Mass method is employed to establish a numerical model,and the factors affecting coal post-peak characteristics are analyzed from four perspectives:coal matrix mechanical parameters,structural weak surface properties,height-to-width ratio,and loading rate.The research identifies four significant influencing factors:deformation modulus,density of discrete fracture networks,height-to-width ratio,and loading rate.The response and sensitivity of post-peak characteristics to single-factor and multi-factor interactions are assessed.The result suggested that feasible prevention and control measures for coal bursts can be formulated through four approaches:weakening the mechanical properties of coal pillars,increasing the number of structural weak surfaces in coal pillars,reducing the width of coal pillars,and optimizing mining and excavation speed.The efficacy of measures aimed at weakening the mechanical properties of coal is successfully demonstrated through a case study on coal burst prevention using large-diameter borehole drilling.
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supported by the National Nature Science Foundation of China(51904153)funding of Tiandi Science&Technology Co Ltd(2022-2-TD-QN008,KJ2019-TDKCSYS-01).
文摘Accurate estimation of the triaxial compression behavior of jointed coal is essential for coal mining.Few studies addressed the triaxial compression behavior of large-scale rock mass,especially with real joint geometry.We employed a numerical synthetic rock mass(SRM)method to study the triaxial compression behavior of jointed coal.Jointed-coal specimens were constructed based on in-situ joint measurements and microparameter calibration against laboratory experiments.A series of triaxial compression tests under different loading orientations and confining pressures were numerically performed to obtain joint and confining-pressure effects on the triaxial compression behavior and reveal the failure mechanism of jointed coal.Results suggest that the triaxial compression behavior of the jointed coal has strong joint and confining-pressure effects.Joints weaken the strength and elastic modulus,reduce the lateral deformation,and affect the geometries of the shear-rupture surface.An increase in the confining pressure causes the peak and residual strength increase significantly.With an increase in the confining pressure,the elastic modulus increases sharply at low confining pressure,the mechanical behavior transitions from brittleness to ductility,the failure mode transitions from shear-rupture surface to plastic flow,and the joint effect diminishes and even disappears.The jointed coal fails by means of a shear-rupture surface under triaxial compression loading with a confining pressure(which is not too high),and the geometries of the shear-rupture surface vary with the distribution of joints.
基金the Nuclear Waste Management Organization (NWMO) of Canadathe National Science and Engineering Research Council (NSERC)+1 种基金the Canadian Ministry of National Defence (DND)the RMC Green Team for funding this research
文摘The main objective of this paper is to examine the influence of the applied confining stress on the rock mass modulus of moderately jointed rocks（well interlocked undisturbed rock mass with blocks formed by three or less intersecting joints）. A synthetic rock mass modelling（SRM） approach is employed to determine the mechanical properties of the rock mass. In this approach, the intact body of rock is represented by the discrete element method（DEM）-Voronoi grains with the ability of simulating the initiation and propagation of microcracks within the intact part of the model. The geometry of the preexisting joints is generated by employing discrete fracture network（DFN） modelling based on field joint data collected from the Brockville Tunnel using LiDAR scanning. The geometrical characteristics of the simulated joints at a representative sample size are first validated against the field data, and then used to measure the rock quality designation（RQD）, joint spacing, areal fracture intensity（P21）, and block volumes. These geometrical quantities are used to quantitatively determine a representative range of the geological strength index（GSI）. The results show that estimating the GSI using the RQD tends to make a closer estimate of the degree of blockiness that leads to GSI values corresponding to those obtained from direct visual observations of the rock mass conditions in the field. The use of joint spacing and block volume in order to quantify the GSI value range for the studied rock mass suggests a lower range compared to that evaluated in situ. Based on numerical modelling results and laboratory data of rock testing reported in the literature, a semi-empirical equation is proposed that relates the rock mass modulus to confinement as a function of the areal fracture intensity and joint stiffness.
文摘裂隙岩质高边坡稳定性的变形破坏模式实际上取决于其岩体结构特征所控制的潜在路径形式。在复杂裂隙岩体结构边坡中,不同类型和规模的陡缓结构面交切组合将其破坏路径更加不确定化。复合岩体技术(synthetic rock mass,SRM)可有效实现受结构控制的滑移破坏。遵循该理念指导,以西南某水电工程复杂裂隙岩质高边坡为例,采用颗粒离散元PFC软件平台研发的SRM技术,解决了利用均质区划分为基础的非均匀分布的规模不同的陡缓结构面复杂网络模型构建、考虑颗粒尺寸效应范围的不同工程地质性状岩石材料模型构建、以及结合重度增加法计算复合岩体模拟裂隙岩质高边坡潜在失稳路径的技术难题,收效颇丰。模拟结果表明:该边坡潜在失稳的主要路径为陡倾的断层、岩脉与倾向坡外的长大中缓倾角裂隙组合形成阶梯状形式,其潜在失稳路径以浅表局部的剪切–拉张失稳模式为主,为该工程后续的边坡设计提供了可靠的边界范围和指导意义。本项研究方法和结论具有可观的推广价值和普适性。
