基于非共轴本构模型的砂土真三轴试验分叉分析  

Bifurcation analysis in true traxial tests on sands based on non-coaxial elasto-plasticity model

作　　者：吕玺琳[1] 黄茂松[2] 钱建固[1] 

机构地区：[1]同济大学岩土与地下工程教育部重点实验室,上海200092 [2]同济大学地下建筑与工程系,上海200092

出　　处：《岩土工程学报》2008年第5期646-651,共6页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金资助项目(10402029);国家自然科学基金资助项目(50679090)

摘　　要：现有的弹塑性本构模型多数是基于共轴理论建立的,且只在三轴压缩应力条件下得到验证,因而不能合理描述真三轴状态下砂土的力学特性。为此,改进三维本构模型屈服函数的π面形态,运用非共轴分叉理论对真三轴状态下砂土的分叉强度与分叉前的应力应变关系进行分析。理论分析表明,真三轴条件下中主应力对分叉前应力应变曲线及分叉特性有着显著的影响,其中中主应力比超过0.2时应变局部化产生并决定了土体的峰值强度。真三轴试验结果与传统的共轴分叉理论的预测结果进行对比分析,验证了非共轴分叉理论预测的合理性。For numerous constitutive models are established based on the coaxial theory and validated only under triaxial compression condition, the soil behavior is inaccurately described under the true triaxial condition. A 3D non-coaxial elasto-plasticity model with a novel-surface shape was proposed to simulate stress-strain curves before bifurcation and to predict the bifurcation strength. It was shown that both the pre-bifurcation deformation and the bifurcation strength were strongly affected by the intermediate principal stress, and the peak failure stemmed from the onset of strain localization when the ratio of intermediate principal stress was beyond 0.2. It was shown by comparisons between the predicted and experimental results on dense sands that the 3D non-coaxial model was more reasonable to be used to predict the bifurcation strength than the coaxial one under the true triaxial condition.

关 键 词：真三轴试验 非共轴 弹塑性本构模型 分又 应变局部化 

分 类 号：TU411[建筑科学—岩土工程]