循环荷载作用下饱和软粘土累积变形研究

摘要

在天津滨海饱和重塑软粘土不排水循环三轴试验的基础上,分析了不同静、动应力组合影响下软粘土的累积变形规律.基于静蠕变理论,提出一种长期循环荷载作用下饱和软粘土轴向循环累积塑性应变经验模型,其中,用双曲线函数来表示软粘土轴向累积应变与循环次数的关系,用指数函数来表示累积应变与相对偏应力水平的关系.以有限元软件ABAQUS为平台进行二次开发,通过用户子程序CREEP将该模型嵌入有限元数值模型中,并利用室内三轴不排水循环蠕变的试验结果对本文经验模型的数值计算结果进行验证.最后,将该数值计算模型应用到防波堤工程实例中,分析了软土地基的循环累积变形的变化规律.研究成果可为软粘土地基上港口与海岸水工建筑物的设计提供参考.%Based on the undrained cyclic triaxial tests on the remoulded saturated soft clay in Tianjin littoral area, the accumulative deformation of soft clay was performed considering the effect of cyclic deviatoric stress and initial static deviatoric stress. Based on the creep theory of static stress, an empirical model was proposed to calculate the plastic cumulative strain of saturated clay subjected to cyclic loading. The relationship between the axial cumulative strain and the cyclic number can be described with a hyperbolic function. And the relationship between the axial cumulative strain and the relative deviatoric stress level can be described with an exponential function. Based on user subroutines CREEP of finite element program ABAQUS, the proposed empirical model was secondarily developed and verified by undrained cyclic triaxial creep test. And this method was applied to the certain breakwater engineering instance to analyze the cyclic cumulative deformation, which may provide reference for the designing of harbor engineering structure.