A STUDY ON DETERIORATION OF DEFORMATION AND STRENGTH CHARACTERISTICS OF SATURATED CLAYS SUBJECTED TO CYCLIC LOADING BASED ON DAMEGE MECHANICS

基于损伤力学的饱和粘土循环荷载变形劣化及强度特性研究

• 批准号: 60550352
• 负责人: MATSUI Tamotsu
• 金额: $ 1.22万
• 依托单位: OSAKA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1986
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60550352/
• 关键词: Cyclic loading; Saturated clay; Deformation strength; 劣化現象

In this research, investigated was the deterioration of strength and deformation characteristics of saturated clays subjected to cyclic loading, being based on the concept in damage mechanics. For two-year periods of project, a series of undrained cyclic triaxial tests was carried out for normally consolidated clays and over-consolidated clays. In the first year, the deteriorative characteristics of mechanical properties of saturated clays subjected to cyclic loading were investigated through experimental results of normally consolidated clays, and the characteristics of deterioration were formulated in term of an index of deterioration (damage variable). In the second year, undrained cyclic triaxial tests for over-consolidated clays were performed, and the applicability of the proposed method to the cases of over-consolidated clays was examined.The main conclusions in this research are summerized as follows:(1) The deformation characteristics of saturated clays deteriorate most remark … More ably during and after cyclic loading. Therefore, it is reasonable to choose the coefficient of deformation as an index of deterioration for saturated clays.(2) The deterioration of deformation characteristics of saturated clays is influenced significantly by the strain rate on cyclic loading.(3) The undrained strengths of the clay subjected to cyclic loading and the over-consolidated clay with static stress history are the same if they are in the same effective stress state. Therefore, the deterioration of the undrained strength of the former can be estimated with the procedure to predict the undrained strength of the latter.(4) The deterioration of deformation characteristics of saturated clays is influenced not only by the decrease of mean effective stress but also by the disturbance due to cyclic loading. To evaluate the effect of the disturbance which is dependent of strain history on cyclic loading, an index of deterioration is proposed newly in this study on the basis of the concept in damage mechanics.(5) A method for predicting the stress-strain relations of saturated clays with cyclic loading history is derived through experimental knowledges, and its applicability to the cases of random cyclic loading is confirmed. Less

本文基于损伤力学的概念，研究了饱和黏土在循环荷载作用下的强度劣化和变形特性。在为期两年的项目期间，对正常固结粘土和超固结粘土进行了一系列不排水循环三轴试验。第一年，通过正常固结粘土的试验结果，研究了饱和粘土在循环荷载作用下力学性能的劣化特征，并将劣化特征用劣化指标（损伤变量）来表述。第二年，对超固结粘土进行了不排水循环三轴试验，验证了该方法对超固结粘土的适用性。结果表明：(1)饱和黏土在循环荷载作用下和循环荷载作用后变形特性恶化最为明显。因此，选择变形系数作为饱和粘土劣化指标是合理的。(2)饱和黏土变形特性的恶化受循环加载应变速率的显著影响。(3)在相同的有效应力状态下，循环荷载作用下的粘土与具有静应力历史的超固结粘土的不排水强度相同。因此，前者不排水强度的恶化可以用预测后者不排水强度的方法来估计。(4)饱和黏土变形特性的恶化不仅受到平均有效应力减小的影响，还受到循环荷载扰动的影响。为了评价依赖于应变历史的扰动对循环加载的影响，本文从损伤力学的概念出发，提出了退化指标。(5)通过实验知识推导出一种具有循环加载历史的饱和粘土应力-应变关系预测方法，并验证了该方法在随机循环加载情况下的适用性。少