This paper presents a model for calculating the small-strain shear stiffness of saturated and unsaturated fine-grained soils as the product of a dimensionless stiffness index and four individual functions of the mean average skeleton stress, the over-consolidation ratio, the reference saturated void ratio and the degree of saturation. The main element of novelty of the model resides in the introduction of a reference saturated state, which results in a dependency of the small-strain stiffness on the degree of saturation. The reference saturated state is calculated according to a recently published constitutive law that relates the quotient between the unsaturated void ratio and the reference saturated void ratio to the degree of saturation. The model requires only two extra parameters for unsaturated states, i.e. one parameter for the volumetric behaviour and one for the stiffness behaviour. These two parameters may also be correlated to the saturated parameters, which simplifies the calibration of the model. The proposed framework is validated against laboratory experiments on three different materials resulting in generally accurate predictions compared to other published models. The good predictive capabilities and the simplicity of the formulation justify the implementation of the model into numerical codes for the analysis of geotechnical problems.

本文提出了一个计算饱和和不饱和细粒土的小应变剪切刚度的模型，该模型是无因次刚度指数与平均骨架平均应力，超固结比，参考饱和空隙的四个独立函数的乘积比率和饱和度。该模型的新颖性主要在于参考饱和状态的引入，这导致了小应变刚度对饱和度的依赖性。参考饱和状态根据最近发布的本构定律计算，该定律将不饱和空隙率与参考饱和空隙率之间的商与饱和度相关联。对于不饱和状态，该模型仅需要两个额外的参数，即 一个参数用于体积行为，另一个参数用于刚度行为。这两个参数也可以与饱和参数相关联，从而简化了模型的校准。相对于其他已发布的模型，所提出的框架针对三种不同材料的实验室实验进行了验证，从而得出了大致准确的预测。良好的预测能力和公式的简单性证明了将模型实施为用于分析岩土工程问题的数字代码的合理性。相对于其他已发布的模型，所提出的框架针对三种不同材料的实验室实验进行了验证，从而得出了大致准确的预测。良好的预测能力和公式的简单性证明了将模型实施为用于分析岩土工程问题的数字代码的合理性。相对于其他已发布的模型，该框架针对三种不同材料的实验室实验进行了验证，从而得出了大致准确的预测。良好的预测能力和公式的简单性证明了将模型实施为用于分析岩土工程问题的数字代码的合理性。