双轴压缩试验中砂土剪切带形成的离散元模拟分析  

DEM simulation of the shear band of sands in biaxial tests

作　　者：蒋明镜[1,2] 李秀梅[1,2] 

机构地区：[1]同济大学土木学院地下建筑与工程系,上海200092 [2]同济大学岩土及地下工程教育部重点实验室,上海200092

出　　处：《山东大学学报（工学版）》2010年第2期52-58,共7页Journal of Shandong University（Engineering Science）

基　　金：国家自然科学基金资助项目(50679057;10972158)

摘　　要：采用离散单元法软件PFC2D模拟了大量砂土试样双轴试验,分析了砂土剪切带形成机理及发展过程,并通过研究试样剪切带内外应力-应变关系及孔隙比、平均接触数及配位数等参数的变化情况,研究了带内外宏微观性质的差异。研究表明:砂土剪切带的形成过程即为试样内部应变局部化过程,也为试样内部平均转动率(aver-aged pure rotation rate,APR)的局部化;剪切带开始形成点也为试样剪缩、剪胀分界点;剪切带内外各宏微观参数变化规律上存在明显的差异,主要表现为近剪切带位置土体及带内土表现为应变软化现象,而距带中心较远土体应力应变关系曲线出现'回滞圈'现象;带内变形量明显大于带外,且带内较带外松散。Many biaxial tests of sands are simulated using PFC2D to study the formation and the development of the shear band.The relationship of stress and strain inside or outside the shear band is studied.Focus is extended to some variables such as the void ratio,the average coordination number and the pure rotation ratio inside and outside the shear band.The results show that the formation of the shear band is characterized with both strain localization and the localization of the averaged pure rotation ratio（APR）.The shear band starts right at the point where the volume strain changes from shrinkage to expansion.The development of these variables are significantly different within or outside of the shear band.Particularly,the stress-strain softening relationship was observed near or within the shear band,while the hysteretic phenomenon takes place outside the shear band.In addition,both the volumetric and deviatoric strains are larger inside than outside the shear band,with the soil being looser in the shear band.

关 键 词：离散元 剪切带 砂土 双轴试验 应变软化 

分 类 号：TU442[建筑科学—岩土工程]