The mechanical characteristics and acoustic behavior of rock masses are greatly influenced by stochastic joints.In this study,numerical models of rock masses incorporating intermittent joints with different numbers an...The mechanical characteristics and acoustic behavior of rock masses are greatly influenced by stochastic joints.In this study,numerical models of rock masses incorporating intermittent joints with different numbers and dip angles were produced using the finite element method(FEM)with the intrinsic cohesive zone model(ICZM).Then,the uniaxial compressive and wave propagation simulations were performed.The results indicate that the joint number and dip angle can affect the mechanical and acoustic properties of the models.The uniaxial compressive strength(UCS)and wave velocity of rock masses decrease monotonically as the joint number increases.However,the wave velocity grows monotonically as the joint dip angle increases.When the joint dip angle is 45°–60°,the UCS of the rock mass is lower than that of other dip angles.The wave velocity parallel to the joints is greater than that perpendicular to the joints.When the dip angle of joints remains unchanged,the UCS and wave velocity are positively related.When the joint dip angle increases,the variation amplitude of the UCS regarding the wave velocity increases.To reveal the effect of the joint distribution on the velocity,a theoretical model was also proposed.According to the theoretical wave velocity,the change in wave velocity of models with various joint numbers and dip angles was consistent with the simulation results.Furthermore,a theoretical indicator(i.e.fabric tensor)was adopted to analyze the variation of the wave velocity and UCS.展开更多
It has been well recognized that, due to anisotropic packing structure of granular material, the true stress in a specimen is different from the applied stress. However, very few research efforts have been focused on ...It has been well recognized that, due to anisotropic packing structure of granular material, the true stress in a specimen is different from the applied stress. However, very few research efforts have been focused on quantifying the relationship between the true stress and applied stress. In this paper, we derive an explicit relationship among applied stress tensor, material-fabric tensor, and force-fabric tensor; and we propose a relationship between the true stress tensor and the applied stress tensor. The validity of this derived relationship is examined by using the discrete element simulation results for granular material under biaxial and triaxial loading con- ditions.展开更多
颗粒材料的宏观力学行为与接触网络的组构各向异性密切相关,根据接触点的滑动与否、转动与否和强弱力情况,可以将颗粒间的接触系统分为不同的子接触网络.一般而言,不同的子接触网络在颗粒体系中的传力机制不同,对宏观力学响应的贡献也...颗粒材料的宏观力学行为与接触网络的组构各向异性密切相关,根据接触点的滑动与否、转动与否和强弱力情况,可以将颗粒间的接触系统分为不同的子接触网络.一般而言,不同的子接触网络在颗粒体系中的传力机制不同,对宏观力学响应的贡献也有不同.采用离散单元法(discrete element method,DEM)模拟了不同抗转动系数μ_(r)下颗粒材料三轴剪切试验,分析了剪切过程中不同子接触网络的组构张量的演变规律,并探究了颗粒抗转动效应对子接触网络各向异性指标演变规律的影响.研究发现:剪切过程中转动、非转动接触的组构张量变化不是独立的,受到颗粒间滑动与否的影响;非滑动、强接触网络是颗粒间的主要传力结构,非滑动接触网络的接触法向和法向接触力各向异性均随μ_(r)的增大而增大,其对宏观应力的贡献程度随μ_(r)的增大而减小;强接触网络的接触法向各向异性随μ_(r)的增大而增大,但法向接触力各向异性随μ_(r)的增大无明显变化,强接触网络对宏观应力的贡献程度在不同μ_(r)情况下均相同.展开更多
基金financial support from the National Key R&D Program of China(Grant No.2020YFA0711802).
文摘The mechanical characteristics and acoustic behavior of rock masses are greatly influenced by stochastic joints.In this study,numerical models of rock masses incorporating intermittent joints with different numbers and dip angles were produced using the finite element method(FEM)with the intrinsic cohesive zone model(ICZM).Then,the uniaxial compressive and wave propagation simulations were performed.The results indicate that the joint number and dip angle can affect the mechanical and acoustic properties of the models.The uniaxial compressive strength(UCS)and wave velocity of rock masses decrease monotonically as the joint number increases.However,the wave velocity grows monotonically as the joint dip angle increases.When the joint dip angle is 45°–60°,the UCS of the rock mass is lower than that of other dip angles.The wave velocity parallel to the joints is greater than that perpendicular to the joints.When the dip angle of joints remains unchanged,the UCS and wave velocity are positively related.When the joint dip angle increases,the variation amplitude of the UCS regarding the wave velocity increases.To reveal the effect of the joint distribution on the velocity,a theoretical model was also proposed.According to the theoretical wave velocity,the change in wave velocity of models with various joint numbers and dip angles was consistent with the simulation results.Furthermore,a theoretical indicator(i.e.fabric tensor)was adopted to analyze the variation of the wave velocity and UCS.
基金the financial support of the National Natural Science Foundation of China(51178044)Program for New Century Excellent Talents in University (NCET-11-0579)
文摘It has been well recognized that, due to anisotropic packing structure of granular material, the true stress in a specimen is different from the applied stress. However, very few research efforts have been focused on quantifying the relationship between the true stress and applied stress. In this paper, we derive an explicit relationship among applied stress tensor, material-fabric tensor, and force-fabric tensor; and we propose a relationship between the true stress tensor and the applied stress tensor. The validity of this derived relationship is examined by using the discrete element simulation results for granular material under biaxial and triaxial loading con- ditions.
文摘颗粒材料的宏观力学行为与接触网络的组构各向异性密切相关,根据接触点的滑动与否、转动与否和强弱力情况,可以将颗粒间的接触系统分为不同的子接触网络.一般而言,不同的子接触网络在颗粒体系中的传力机制不同,对宏观力学响应的贡献也有不同.采用离散单元法(discrete element method,DEM)模拟了不同抗转动系数μ_(r)下颗粒材料三轴剪切试验,分析了剪切过程中不同子接触网络的组构张量的演变规律,并探究了颗粒抗转动效应对子接触网络各向异性指标演变规律的影响.研究发现:剪切过程中转动、非转动接触的组构张量变化不是独立的,受到颗粒间滑动与否的影响;非滑动、强接触网络是颗粒间的主要传力结构,非滑动接触网络的接触法向和法向接触力各向异性均随μ_(r)的增大而增大,其对宏观应力的贡献程度随μ_(r)的增大而减小;强接触网络的接触法向各向异性随μ_(r)的增大而增大,但法向接触力各向异性随μ_(r)的增大无明显变化,强接触网络对宏观应力的贡献程度在不同μ_(r)情况下均相同.
