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在深入探讨海相沉积原状软黏土压缩、变形等力学特性和详细分析加载屈服面随荷载情况变化的基础上,确认了海相沉积原状软黏土的强度、变形特性与结构屈服应力密切相关。即当固结压力小于结构屈服应力时,其力学特性与超固结重塑土的力学特性类似;当固结压力大于结构屈服应力时,其力学特性与正常固结重塑土的力学特性类似。为描述海相沉积原状软黏土的上述力学特性,将姚仰平等提出的超固结重塑土本构模型引入到海相沉积软黏土弹塑性本构模型的构建中。在本构模型构建过程中,考虑了海相沉积原状软黏土具有的抗拉强度及其演化规律,软黏土强度包线的特点及其进一步修正的表达式,使模型更符合海相原状软黏土的强度、变形特性。最后,将3种不同海相沉积软黏土固结排水剪切试验得到的应力-应变-体变曲线与模型预测结果进行对比。比较结果显示,本文提出的弹塑性本构模型能很好地描述海相沉积原状软黏土的剪缩硬化、剪胀软化以及变形的应力水平依存性等力学特性。
Based on the study of mechanical properties such as compression and deformation of undisturbed soft clay in marine sediments and the detailed analysis of the change of load yield surface with load, it is confirmed that the strength and deformation of undisturbed soft clay with marine sediments are closely related to the structural yield stress. When the consolidation pressure is less than the structural yield stress, its mechanical properties are similar to the mechanical properties of the overconsolidated remolded soil. When the consolidation pressure is greater than the structural yield stress, its mechanical properties are similar to the mechanical properties of the normal consolidated remolded soil . In order to describe the above-mentioned mechanical properties of marine soft clay, the over-consolidated remolded soil constitutive model proposed by Yao Yang-ping et al. Was introduced into the construction of elastoplastic constitutive model of marine soft clay. In the construction process of the constitutive model, considering the tensile strength and evolution law of the original soft clay with marine sediment, the characteristics of the soft clay strength envelope and its further revised expression, the model is more in line with the marine undisturbed soft clay Strength, deformation characteristics. Finally, the stress-strain-body deformation curves obtained from the consolidation tests of three kinds of marine sedimentary soft clay were compared with the model predictions. The results show that the elastic-plastic constitutive model proposed in this paper can well describe the mechanical properties such as shear-shrinkage hardening, dilatancy softening and deformation stress level dependence of marine soft clay.