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张紧式吸力锚是一种重要的深水海洋浮式平台锚固基础。静荷载与循环荷载共同作用下地基土体产生较大变形,严重影响吸力锚基础的稳定性。介绍了一种能够描述饱和软黏土不排水循环应力应变响应的拟动力黏弹塑性本构模型。该模型将等效黏弹性理论和蠕变理论相结合,利用等效黏弹性模型描述土单元循环应力应变关系中的非线性和滞回性,依据蠕变关系描述土单元的循环累积性。基于拟动力黏弹塑性本构模型,提出了一种分析静荷载与循环荷载共同作用下软土中张紧式吸力锚基础变形过程的拟动力黏弹塑性有限元方法。该方法并不详细追踪土单元的循环应力应变响应,而是将循环次数视为时间,通过等效黏弹性分析确定吸力锚基础的循环变形;根据土单元静应力和循环累积应变势,采用初应变法确定吸力锚基础的累积变形。结合循环变形和累积变形,确定吸力锚基础变形随时间的变化关系,即位移时程曲线。最后,将有限元计算结果与1g条件下吸力锚模型试验结果进行比较,结果显示两者基本一致。
Tension suction anchor is an important anchor for deep-sea floating platform. Under the action of static load and cyclic load, the soil in the foundation has a large deformation, which seriously affects the stability of the suction anchor foundation. A pseudo-elasto-visco-elastoplastic constitutive model describing the cyclic stress-strain response of undrained saturated soft clay is presented. In this model, the equivalent viscoelastic theory and creep theory are combined. The equivalent viscoelastic model is used to describe the nonlinearity and hysteresis in the cyclic stress-strain relationship of soil elements. The cyclic cumulative of soil elements is described based on the creep relationship. Based on the pseudo-elasto-visco-elasto-plastic constitutive model, a pseudo-dynamic viscoelastic-plastic finite element method is presented to analyze the deformation process of the tensioned suction anchor foundation in soft soil under static and cyclic loads. The method does not trace the cyclic stress-strain response of soil units in detail, but regards the number of cycles as the time and determines the cyclic deformation of the suction anchor based on the equivalent viscoelasticity analysis. According to the static stress and cyclic cumulative strain potential of soil units, Strain Method to Determine Cumulative Deformation of Suction Anchor Foundation. Combined with cyclic deformation and cumulative deformation, the relationship between the deformation of suction anchor foundation and the time, that is, the displacement time history curve, is determined. Finally, the results of finite element method and suction anchor model test under 1g conditions are compared, the results show that the two are basically the same.