The interparticle bonding effect due to water menisci plays an important role in the hydromechanical coupling properties of unsaturated soils. This paper presents an unsaturated hydromechanical coupling model that considers the influence of matric suction, degree of saturation, and microscopic pore structure on the interparticle bonding effect. The enhanced effective stress and bonding variable are selected as constitutive variables. The bonding variable is correlated with the ratio between unsaturated void ratio and saturated void ratio. The deformation characteristics of unsaturated soils are described based on the bounding surface plasticity theory. A soil–water characteristic model that considers deformation and hydraulic hysteresis is integrated into the constitutive model to achieve hydromechanical coupling. The proposed model can effectively describe the hydromechanical coupling characteristics and the meniscus bonding force of unsaturated bimodal structure soils; the model parameters can be easily obtained through routine experiments. The experimental results of unsaturated isotropic compression, the wetting/drying cycle, and unsaturated triaxial shear tests are used to validate the capability of the proposed model.

水半月板引起的颗粒间结合作用在非饱和土壤的水力耦合特性中起着重要作用。本文提出了一种不饱和流体力学耦合模型，该模型考虑了基质吸力，饱和度和微观孔隙结构对颗粒间键合效应的影响。选择增强的有效应力和结合变量作为本构变量。结合变量与不饱和空隙率和饱和空隙率之比相关。基于边界面可塑性理论描述了非饱和土的变形特征。考虑变形和水力滞后的土壤-水特征模型被集成到本构模型中以实现水力耦合。该模型可以有效地描述非饱和双峰结构土的水力耦合特性和弯月面粘结力。通过常规实验可以很容易地获得模型参数。非饱和各向同性压缩，润湿/干燥循环以及非饱和三轴剪切试验的实验结果用于验证所提出模型的能力。