基于宏细观分析的砂土各向异性本构模拟

项目名称： 基于宏细观分析的砂土各向异性本构模拟

项目编号： No.50808159

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 杨仲轩

作者单位： 浙江大学

项目金额： 20万元

中文摘要： 砂土各向异性是其力学行为复杂多变的原因所在。在分析一些与砂土有关的重大工程时，存在着大量的不确定性，这在客观上要求深入了解其复杂的力学行为。本项目拟提出一套实验方法来探明砂土的各向异性，并对其细观结构进行客观的定量化描述。借助试验手段，开展多种应力路径（包括三轴拉伸、压缩、扭剪以及循环荷载）以及各种不同的初始条件（密度和围压）下的试验研究，探究砂土的各向异性力学行为。在此基础上，利用离散元模拟技术，进行数值分析，以校验解释宏观试验结果，并探索细观结构及其发展规律。基于宏细观的研究结果，提出考虑砂土各向异性影响的弹塑性本构方程，用于工程问题的分析。该模型除了能够反映砂土在不同围压和密度条件下的性状，还考虑了材料各向异性和应力各向异性的耦合。研究成果有助于从宏细观两个尺度加深对砂土各向异性本质的认识，在连续介质力学和临界土压力理论的框架下，进一步完善砂土的本构理论。

中文关键词： 各向异性；本构方程；细观分析；离散元模拟；砂土

英文摘要： The mechanical behavior of granular soils is very complex due to its anisotropic nature, thus lots of uncertainties are existed when dealing with some important construction pojects relevant to granular soils. Naturally, it requires an in-depth understanding on the engineering behavior of granular soils udner varoius loading conditions. This project is aimed to develop an experimental procedure to investigate the anisotropy and quantify the microstructure of the granular soils. A series of laboratory tests will be conducted to explore the anisotropic effects of granular soils, under various loading paths, including triaxial compression/extension, torsional shear and cyclic loadings, with different initial testing conditions, such as densities, pressures, and anisotropy intersities resulting from different sample formation methods.Discrete element method (DEM) based numerical simulations are also carried out to verify the macroscopic results obtained from above laboratory tests, and further to study the evolutions of the microstructure and anisotropy during the loading process. Based on the two scales investigations, an anisotropic elasto-plastic constitutive model will be proposed and be applied to the analysis of engineering problems. The model is expected to reflect the behaviors of the granular soils with different confining pressures and initial densities, and also to couple the material fabric anisotropy and stress anisotropy. The major findings resulting from this project may improve our understandings on the granular soil behavior on two scales, and promote the establishment of the constitutive theory of the granular soils in the framework of the continuum mechanics and critical state soil mechanics.

英文关键词： fabric anisotropy;constitutive equations; microscale analysis; discrete element moedlling; granular soils