循环荷载下土体变形特性研究

发布时间：2018-09-13 08:45

【摘要】：为研究循环荷载下土体变形特性,基于已有的分数阶黏壶构建循环荷载下分数阶黏壶,并将其替换为西原模型黏塑性体中的常值黏壶,建立了可描述循环荷载下土体变形规律的分数阶西原模型。当循环荷载应力幅值大于土体临界应力幅值时,模型为反映土体破坏型变形规律的分数阶西原模型;反之,则为反映土体稳定型、临界型变形规律的广义Kelvin模型。采用应力分解法,将循环荷载分解为一个静力荷载和一个平均应力值为0的循环荷载,基于流变力学理论给出了静力作用下基于该模型的流变本构方程,再根据黏弹性力学理论构建了交变应力作用下基于该模型的动态响应本构方程,将已获得的土体流变本构方程与动态响应本构方程叠加,得到新的土体本构方程。结果表明:与既有的试验结果相比,基于分数阶西原模型所建立的本构方程可较好描述循坏荷载下土体各种类型的变形特征,对土体各类型变形曲线的拟合效果较好,拟合系数均在0.90以上,且模型参数值随循环荷载动应力幅值的增大而以幂函数形式减小。
[Abstract]:In order to study the deformation characteristics of soil under cyclic loading, the fractional viscosity pot under cyclic load was constructed based on the existing fractional viscosity pot, and replaced with the constant viscosity pot in the original viscoplastic body. A fractional western-order model is established to describe the deformation of soil under cyclic loading. When the amplitude of cyclic load stress is larger than the critical stress amplitude of soil, the model is a fractional western-original model which reflects the law of soil failure deformation, whereas the generalized Kelvin model reflects the law of soil stability and critical deformation. By using the stress decomposition method, the cyclic load is decomposed into a static load and a cyclic load with an average stress value of 0. Based on the rheological mechanics theory, the rheological constitutive equation based on the model is given. Based on the viscoelastic mechanics theory, the dynamic response constitutive equation based on the model is constructed, and the obtained soil rheological constitutive equation is superposed with the dynamic response constitutive equation, and a new soil constitutive equation is obtained. The results show that compared with the existing experimental results, the constitutive equation based on the fractional western-model can better describe the deformation characteristics of various types of soil under bad load, and the fitting effect of the deformation curves of each type of soil is better. The fitting coefficients are all above 0.90, and the model parameters decrease in the form of power function with the increase of dynamic stress amplitude of cyclic load.
【作者单位】：贵州大学土木工程学院;北京科技大学土木与环境工程学院;贵州大学喀斯特环境与地质灾害防治教育部重点实验室;
【基金】：国家自然科学基金资助(No.51608141) 贵州大学引进人才科研项目(No.贵大人基合字(2015)16)~~
【分类号】：TU433

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