结构性海洋黏土损伤模型的二次开发及应用

原状土的结构性作为21世纪土力学的核心问题，一直以来受到学者们的广泛关注。软黏土的结构性损伤这一力学行为会对海洋结构物基础造成不可忽略的影响。以海底原状土的结构性特征为研究对象，推导了考虑黏土结构性的SANICLAY模型的数值实现格式。通过子增量步显式算法和有限元的二次开发，实现了结构性多屈服面本构模型在有限元方法中的应用。通过与不同应力路径下的三轴试验结果对比，验证了开发的子程序可准确模拟海洋黏土所具有的结构性。基于不同应力路径试验的数值模拟结果，研究了不同固结和剪切条件下土体塑性势面和屈服面的演化规律，揭示了土体固结可降低结构性损伤程度以及剪切过程中土体产生结构性损伤的机制。将二次开发的子程序应用到具体的边值问题中，开展了可考虑土体结构性影响的海上风电筒型基础静承载力研究，揭示了土体结构性对筒型基础的地基破坏模式、峰值承载力和残余承载力的影响；引入残余衰减比来表征土体结构性破坏后筒型基础的残余承载力，并建立了残余衰减比与结构损伤因子之间的关系。

Secondary development and application of structural marine clay damage model

As the core issue of soil mechanics in the 21st century, the structure of undisturbed soil has been widely concerned. In particular, the mechanical behavior of structural damage in soft clay will pose a non-negligible impact on the foundation in offshore engineering. This paper takes the structural characteristics of the undisturbed submarine soil as the research object, and derives the numerical implementation format of the SANICLAY model considering the structure of the clay. Based on the analysis of the triaxial test results of the undisturbed marine clay, it is found that the marine soils have significant structural damage mechanical behaviors which means soil strength would reduce under static deviatoric stress. Through the Substepping Explicit Integral Algorithm method, the multi-yield surface soil constitutive model which can accurately reflect the structure damage of the marine soil is established. The evolutions of plastic potential surface and yield surface of soil under different consolidation conditions and shear conditions are studied. It is revealed that consolidation can reduce the degree of structural damage of the marine soil. Also, the occurrence of structural damage of the marine soil in the shearing process mechanism is illustrated. A series of analyses of the static bearing capacity of the bucket foundation that can consider the influence of the structured soil is carried out. The influence of the soil structure on the failure mode of the bucket foundation is analyzed. Through the parametric analysis of the structural damage factor, the change of the peak bearing capacity and the residual bearing capacity are studied; the concept of residual attenuation ratio is proposed to describe the residual bearing capacity of the foundation after the soil structure is completely lost. The relationship between residual attenuation ratio and the structural damage factor is established.