砂土循环累积变形规律与显式计算模型研究

发布时间：2019-04-03 06:20

【摘要】：海洋基础在上部结构风和波浪等长期循环荷载的作用下产生累积变形,易影响海上风电机组等构筑物的正常服役性能,其本质是基础周边土体的循环累积变形问题。针对该问题,开展了一系列饱和砂土在排水条件下的循环剪切三轴试验,研究了动应力比、初始密实度、初始平均应力和初始静应力比等土性和应力参数对循环累积变形的影响,发现随动应力比、初始平均应力和初始静应力比的增大及初始密实度的减小,饱和砂土的轴向循环累积应变增大。从试验数据分析来看砂土轴向循环累积应变和循环次数之间近似存在双对数线性关系。将砂土轴向循环累积应变与第一次循环轴向应变归一化能消除上述土性和应力参数的影响,进而分析了第一次循环轴向应变与土性和应力参数之间的关系,通过引入与密实度相关的砂土抗剪强度计算表达式,建立了饱和砂土在排水条件下的循环累积变形显式计算模型,适合海洋基础长期循环累积变形分析。
[Abstract]:The accumulative deformation of offshore foundation under long-term cyclic load such as wind and wave of superstructure is easy to affect the normal service performance of offshore wind turbine and other structures. Its essence is the cyclic cumulative deformation of soil around the foundation. In order to solve this problem, a series of cyclic shear triaxial tests of saturated sand under drainage conditions were carried out, and the dynamic stress ratio and initial compactness were studied. The effects of initial average stress, initial static stress ratio and other soil properties and stress parameters on cyclic cumulative deformation are studied. It is found that with the increase of dynamic stress ratio, initial average stress ratio and initial static stress ratio, and the decrease of initial density degree, the initial mean stress ratio and initial static stress ratio increase, and the initial density decreases. The axial cyclic cumulative strain of saturated sand increases. According to the experimental data, there is a double logarithmic linear relationship between the axial cyclic cumulative strain and the number of cycles. The normalized energy of the axial cyclic cumulative strain and the first cyclic axial strain can eliminate the influence of the soil properties and stress parameters, and then the relationship between the first cyclic axial strain and the soil properties and stress parameters is analyzed. An explicit model for calculating cyclic cumulative deformation of saturated sandy soil under drainage conditions is established by introducing a formula for calculating the shear strength of sandy soil related to compactness, which is suitable for long-term cyclic cumulative deformation analysis of marine foundation.
【作者单位】：浙江大学软弱土与环境土工教育部重点实验室;浙江大学岩土工程研究所;国家海洋局第二海洋研究所;
【基金】：国家自然科学基金面上项目(51179169)
【分类号】：TU441;TU433

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