摘要
黄土的宏观力学行为受其微观结构影响显著,为探究非饱和重塑与结构性黄土在平面应变条件下的宏微观力学性质,采用考虑粒间吸引力与化学胶结的非饱和结构性黄土胶结接触模型,开展了非饱和重塑与结构性黄土常含水率条件下的平面应变三维离散元模拟。分析了平面应变条件下不同有效围压对黄土宏观力学行为的影响,并探究其微观机理。模拟结果表明:有效围压对非饱和重塑黄土与结构性黄土应力应变响应影响存在较大差异。非饱和重塑黄土在较小有效围压时呈应变硬化,随有效围压的增大逐步过渡为应变软化,而结构性黄土在不同有效围压下均表现为应变软化,且围压越小,应变软化越显著。在微观尺度上,胶结达到轴向应变2%时开始持续破坏,对于结构性土的峰值应力影响显著;胶结同时会阻碍结构性土各向异性发展。
The macro mechanical behaviors of loess can be dramatically affected by its complex micro properties.In this study,we focused on the unsaturated structural and remolded loesses.Several simulation tests were conducted by distinct element method(DEM).First,a practicable three-dimensional contact model was employed for unsaturated structural loess by considering the effects of adhesive force and chemical cementation,and was then introduced into DEM to simulate the mechanical behavior of loess particulates.Second,a series of plain strain tests were conducted under different confining pressures and constant water content.The effects of confining pressure on the unsaturated remolded and structural loesses were then analyzed in link with macroscopic and microscopic scales.The results show that a strain hardening behavior was demonstrated on the stress-strain relationship of remolded loess at the confining pressure of 100 kPa,and then gradually changes to strain softening with the increase of confining pressure.Whereas the strain softening behavior was demonstrated on the structural loess under all confining pressures,and it becomes more significant with the decrease of confining pressure.At the microscopic scale,the bond breakage continually occurred at the threshold value of 2%axial strain.The peak deviatoric stress is significantly affected by bond breakage.In addition,the chemical cementation is capable of hindering the anisotropic evolution of structural loess.
作者
蒋明镜
王优群
卢国文
张鹏
JIANG Mingjing;WANG Youqun;LU Guowen;ZHANG Peng(Department of Civil Engineering,School of Civil Engineering,Tianjin University,Tianjin 300072,China;State Key Laboratory of Hydraulic Engineering Simulation and Safety,Tianjin University,Tianjin 300072,China;State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China)
出处
《水利与建筑工程学报》
2021年第2期1-5,18,共6页
Journal of Water Resources and Architectural Engineering
基金
国家自然科学基金重点项目(51639008)
国家自然科学基金项目(51579178
51809193)。
