土颗粒材料中的复杂网络结构演化分析

Analysis on evolution of complex network structure of soil granular materials

复杂网络分析方法可应用于土颗粒材料在加载过程中的结构演化分析以及搭建土颗粒材料的微细观与宏观尺度上力学参数之间的联系。主要叙述了我们近十年来采用复杂网络方法分析土颗粒材料的结构演化以及细观参数与宏观力学特性之间的相互关系方面的研究成果。首先介绍了复杂网络中的基本概念(平均度、聚类系数、平均路径长度、力圈);然后分析了双轴条件下的土颗粒材料的细观结构演化以及土坡失稳启动与滑动过程的接触网络参数变化规律;再者分析了考虑颗粒形状、中主应力系数、循环加载路径复杂加载条件下的土颗粒材料的细观结构演化规律;最后,把接触网络的细观结构参数与宏观力学特性相关联,建立了状态参数与平均度、细观结构参数与动强度、平均度和最短路径长度与修正剑桥模型的屈服函数、平均度与基础垂直压力之间的关系,并基于最大流修改了统一硬化模型中参数的取值。

Complex network analysis methods can be applied to analyze the structural evolution of granular materials during loading and establish the relationships of mechanical parameters of these materials between micro/meso and macro scales.This articles mainly reviews our research results in recent years on the structural evolution of granular materials and the relationship between microscopic parameters and macroscopic mechanical properties using complex network methods.Firstly,the basic concepts of complex networks(average degree,clustering coefficient,average path length,and force chain)are introduced.Then,the microstructural evolution of granular materials under biaxial conditions and the network contact parameter changes during the initiation and sliding of soil slopes are analyzed.Furthermore,the microstructure evolution of granular materials considering particle shape,intermediate principal stress coefficient,and complex loading paths is discussed.Finally,the mesoscopic structural parameters of the contact network are associated with the macroscopic mechanical properties,and relationships between the state parameters and average degree,the microscopic structural parameters and soil dynamic strength,the average degree as well as shortest path length and yield function of the modified Cam clay model,and the average degree and the ground vertical pressure are established.The parameters in the unified hardening model are modified based on the maximum flow model.