非均匀颗粒材料的特征长度与相关力学行为的多尺度研究

项目名称： 非均匀颗粒材料的特征长度与相关力学行为的多尺度研究

项目编号： No.11472196

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 楚锡华

作者单位： 武汉大学

项目金额： 80万元

中文摘要： 针对天然砂砾料及人工堆石料等非均匀颗粒材料，系统研究非均匀性对其不同尺度上变形模式与破坏等力学行为的影响。细观上基于离散颗粒模型调查颗粒级配、孔隙分布等对颗粒材料的变形模式、弹性模量及剪切强度的表征元存在性与尺寸的影响，建立剪切带宽度、表征元尺寸等特征长度与平均颗粒直径、颗粒级配及孔隙分布非均匀性之间的联系。宏观上应用均匀化方法发展包含颗粒级配及孔隙分布信息的梯度增强Cosserat连续体模型及有限元数值方案。建立模型中特征长度、表征元尺寸与平均颗粒直径、非均匀度等量的联系，并数值调查特征长度对强度与变形模式的影响。在上述基础上发展基于离散颗粒模型-梯度增强Cosserat连续体模型的两尺度模型及离散元-有限元两尺度数值求解系统。研究结果一方面对颗粒材料多尺度模拟时表征元尺寸的选择提供依据，一方面可加深对尺寸效应机理的认识，为堆石料缩尺条件下实验结果分析和应用提供借鉴。

中文关键词： 颗粒材料；特征长度；尺寸效应；表征元；多尺度模拟

英文摘要： This research project focuses on the effects of heterogeneity of granular materials such as the natural gravel and artificial rockfill materials, on its deformation and failure at different scales. On microscopic level, Discrete Element Method will be used to investigate systematically the effects of particle size distribution (PSD) and local void distribution on deformation patterns, the existence and size of representative volume element (RVE) of different macro phyical properties. The objective of microscopic numerical investigation is to establish the link between PSD, local void distribution and the intrinsic length such as thickness of shear band, size of RVE, of granular materials. In addition, other important issues, such as the dilatancy and vortex structure in shear band related to non-uniform deformations phenomena for granular materials, will be addressed. In the macroscopic framework, gradient enhanced cosserat model which can reflect the micromechanically heterogeneous characters and size effects, and the corresponding numerical scheme based on finite element method (FEM) will be developed. The link between the characteristic length, size of RVE of proposed model and PSD, local void distribution of granular materials will be addressed from theoretical approach. Based on the aforementioned microscopic and macroscopic study work. Two-scale (micro-macro) model based on discrete particle model and the gradient enhanced cosserat model and DEM-FEM two-scale numerical solution will be developed. The results of the proposed project will provide a guide to choice the size of RVE in two-scale simulation, and improve the understanding on size effects of granular materials.

英文关键词： granular materials;intrinsic length scales;size effects;representative volume element;mutiscale modeling