The present study investigates the critical state behaviour of granular assemblies composed of clumped particles under four different drained axisymmetric triaxial stress paths,using the discrete element method(DEM).A...The present study investigates the critical state behaviour of granular assemblies composed of clumped particles under four different drained axisymmetric triaxial stress paths,using the discrete element method(DEM).A series of numerical samples were prepared at initial states with different density indexes(1D)and different initial confining pressures(ρ′0).These samples were sheared to large strains,at which constant stresses and volumes were maintained to reach the critical state.The evolution of stress ratio under the same loading mode(for the same intermediate principal stress ratio,b)is shown to yield an almost identical behaviour independent of stress paths,whereas the stress-strain response depends on the stress paths.Four different axisymmetric stress paths all share the same unique friction angle at critical state,indicating the Mohr-Coulomb failure criterion is the appropriate critical state strength criterion,which is at least true for the axisymmetric stress conditions.A unique coordination number(CN)is achieved at the critical state for a given po,which is independent of the stress path.The critical state CN is found to increase with the increase in po,which could be attributed to the decrease in the critical state void ratio(ec)as mean effective stress(ρ′0)increases.Interestingly,a unique linear functional relationship is found between the critical state values of cN and ec,and a unique polynomial functional relationship is found between the critical state values of CN andρ′.These functional relationships indicate no dependency on the stress paths or loading modes,thus characterizing unique features at critical states at both macroscopic and microscopic levels for a given type of granular material.展开更多
在证明转换规则正确性的基础上,首先利用转换规则对AOE网进行转换,然后从两个方面对转换后的CPN(Colored Petri Nets)模型不合理的地方进行合理性的修改.再利用编写的函数求出从源点到汇点的所有的可达路径,在获得所有可达路径的同时也...在证明转换规则正确性的基础上,首先利用转换规则对AOE网进行转换,然后从两个方面对转换后的CPN(Colored Petri Nets)模型不合理的地方进行合理性的修改.再利用编写的函数求出从源点到汇点的所有的可达路径,在获得所有可达路径的同时也获取了所有可达路径所花费的时间,那么时间最大的就是关键路径.该方法不仅简便直观,而且能够在保证正确性合理性的前提下提高执行效率,减小时间复杂度.展开更多
基金The financial support from Xi'an Jiaotong-Liverpool University(grant Nos.RDF 18-01-23,PGRS1906002 and REF-20-01-01)is gratefully acknowledged。
文摘The present study investigates the critical state behaviour of granular assemblies composed of clumped particles under four different drained axisymmetric triaxial stress paths,using the discrete element method(DEM).A series of numerical samples were prepared at initial states with different density indexes(1D)and different initial confining pressures(ρ′0).These samples were sheared to large strains,at which constant stresses and volumes were maintained to reach the critical state.The evolution of stress ratio under the same loading mode(for the same intermediate principal stress ratio,b)is shown to yield an almost identical behaviour independent of stress paths,whereas the stress-strain response depends on the stress paths.Four different axisymmetric stress paths all share the same unique friction angle at critical state,indicating the Mohr-Coulomb failure criterion is the appropriate critical state strength criterion,which is at least true for the axisymmetric stress conditions.A unique coordination number(CN)is achieved at the critical state for a given po,which is independent of the stress path.The critical state CN is found to increase with the increase in po,which could be attributed to the decrease in the critical state void ratio(ec)as mean effective stress(ρ′0)increases.Interestingly,a unique linear functional relationship is found between the critical state values of cN and ec,and a unique polynomial functional relationship is found between the critical state values of CN andρ′.These functional relationships indicate no dependency on the stress paths or loading modes,thus characterizing unique features at critical states at both macroscopic and microscopic levels for a given type of granular material.
文摘在证明转换规则正确性的基础上,首先利用转换规则对AOE网进行转换,然后从两个方面对转换后的CPN(Colored Petri Nets)模型不合理的地方进行合理性的修改.再利用编写的函数求出从源点到汇点的所有的可达路径,在获得所有可达路径的同时也获取了所有可达路径所花费的时间,那么时间最大的就是关键路径.该方法不仅简便直观,而且能够在保证正确性合理性的前提下提高执行效率,减小时间复杂度.