SGER: Experimental Investigation of Stress Rotation Effects in Soils

SGER：土壤应力旋转效应的实验研究

• 批准号: 0355141
• 负责人: Poul Lade
• 金额: --
• 依托单位: Catholic University of America
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-03-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0355141&HistoricalAwards=false
• 关键词: SGER; Experimental; Investigation; Stress; Rotation

Modeling soil behavior during large stress reversals and modeling cross-anisotropic soil behavior have been done in the past by models formulated in terms of stress invariants and incorporating combinations of isotropic and rotational kinematic hardening. This technique seems to capture the soil behavior observed in triaxial compression and cubical triaxial tests with good accuracy. However, incorporation of measured behavior during large stress reversals in torsion shear tests into the kinematic hardening model has proved to be problematic. In fact, the attempt to include effects of stress rotation in the rotational kinematic model has illuminated why this type of model does not capture all aspects of soil behavior, and why the concepts behind the kinematic hardening models, whether translational or rotational, will not be able to correctly predict soil behavior under general stress conditions, as required in a finite element or finite difference setting. In the experimental investigation, the behavior of granular materials during pure stress rotation will be studied. This condition will highlight the shortcomings of existing isotropic and kinematic hardening models. The research will primarily be performed to (a) demonstrate the shortcoming of existing constitutive models, (b) evaluate the magnitude of the missing plastic strains and consequently the severity of the limitations of the constitutive models, (c) initiate data collection that will indicate the direction of new modeling efforts required to capture the missing capability of predicting effects of stress rotation correctly, and (d) formulate a plan for a more extensive experimental program on the basis of the findings from the exploratory experiments proposed here.Experimental results from torsion shear tests with stress rotation will demonstrate and highlight the extent of the limitations of currently existing isotropic, as well as kinematic hardening constitutive models. These limitations consist of their failure to predict soil behavior correctly in most situations that occur in realistic boundary value problems, and for which they purportedly were developed. This work will have the broader impact that renewed efforts will be forthcoming to update or reformulate constitutive models that will be able to include the effects of stress rotation. The proposed research will therefore have major impact on the future of constitutive modeling and it will impact the FEM and the FDM calculations of boundary value problems involving engineering materials.

过去，在大应力逆转和建模跨 - 鼻部的土壤行为中，建模土壤行为是通过用应力不变剂制定的模型进行的，并结合了各向同性和旋转运动学硬化的组合。该技术似乎捕获了在三轴压缩和立方三轴测试中观察到的土壤行为，其精度良好。然而，事实证明，在扭转剪切测试中大型应力逆转过程中的测量行为纳入运动硬化模型已被证明是有问题的。实际上，试图在旋转运动学模型中包括应力旋转的影响已经阐明​​了为什么这种类型的模型不会捕获土壤行为的各个方面，以及为什么在有限元元素或有限差异设置的一般压力条件下，运动硬化模型（无论是翻译还是旋转）的概念（无论是翻译还是旋转）将无法正确预测土壤行为。 在实验研究中，将研究纯应力旋转过程中颗粒材料的行为。这种情况将突出现有的各向同性和运动学硬化模型的缺点。该研究将主要进行（a）证明现有模型的缺点，（b）评估缺失的塑料菌株的大小，因此评估本构模型局限性的严重性，（c）启动数据收集，该数据收集将指示新建模努力的新建模努力，以捕获捕获压力旋转效果的缺失能力所需的（d），以捕获正式效果，以更高的规划，并以（d）的形式进行（d），并以（d）进行了（d）的计划。在此处提出的探索性实验。与应力旋转的扭转剪切测试的实验结果将证明并强调当前现有各向同性的局限性以及运动硬化的本构模型的限制。这些局限性包括它们在现实的边界价值问题中发生的大多数情况下未能正确预测土壤行为，并且据称它们是为此开发的。这项工作将产生更广泛的影响，即更新的努力将采取更新或重新制定本构模型，以包括压力旋转的效果。因此，拟议的研究将对构造建模的未来产生重大影响，它将影响涉及工程材料的边界价值问题的FEM和FDM计算。