超固结黏土的强度和变形特性受初始孔隙比、应力路径和前期固结应力等状态因素影响。为了描述超固结黏土的状态相关性，本文首先定义密度状态参量和应力状态参量来分别表征当前状态点和对偶状态点与临界状态线之间的孔隙比之差，然后推导出新的应力-状态方程，最后采用状态硬化法则描述当前状态点所在的下加载面的硬化规律，进而建立适用于超固结黏土的状态硬化模型。该模型属于单屈服面模型，形式较为简单，所包含的材料参数可以由常规的室内试验结果进行标定。通过将模型计算结果与不同类型黏土在排水和不排水条件下的三轴压缩试验结果进行对比分析，均取得良好的计算效果，表明本文模型能够合理的描述超固结黏土的应变软化和剪胀特性。模型计算结果表明，前期固结应力会对密度状态参量和应力状态参量的演变规律产生影响，当土样达到临界状态时两者将均取趋近于零。另外，当黏土处于超固结状态时，在排水剪切过程中土样的应力-应变曲线具有明显的软化特性，体积会先减小然后增大；在不排水剪切过程中则会产生负的超孔隙水压。

The strength and deformation behaviours of overconsolidated clay are influenced by various factors such as the initial void ratio, stress path, and preconsolidated stress. To describe the state dependency of overconsolidated clay, this paper introduces the density state parameter and stress state parameter, which help characterize the differences in void ratios between current and dyadic state points. These parameters are utilized in a new constitutive model for overconsolidated soil, which also includes a new state-dependent hardening rule to describe the evolution of the subloading surface where the current state point is located. The proposed model features a single-yield surface to simplify the formula, and its material parameters can be calibrated using conventional laboratory tests. The model's predictions are compared with triaxial test data of various types of clays under drained and undrained conditions, showing good agreement. The comparison results indicate that the evolution of the stress-state parameter and density-state parameter is influenced by the preconsolidated pressure, which reduces to zero once the clay sample reaches the final critical state. Additionally, in preconsolidated clay, the stress-strain curve of the soil sample demonstrates noticeable softening characteristics during the drained shear process, initially resulting in a volume decrease followed by an increase. In the undrained shear process, negative pore water pressure is generated.

天津市教委科研计划项目-自然科学项目-一般项目(XJ2022009601)；天津市教委自然科学计划项目(2018KJ245)