New Unsaturated Dynamic Porosity Hydromechanical Coupled Model and Experimental Validation

Abstract

Constitutive coupled modeling has developed rapidly in recent decades, with numerous new models published. However, few models consider dynamic porosity, and experimental validation of such a model remains a challenge due to multiple variables. In this study, a new constitutive model for unsaturated soil with dynamic porosity was developed based on mixture theory and nonequilibrium thermodynamics, then the model was validated using test data from two experimental studies that yielded good results (relative average error AVRE = 0.8631–1.3046, R2 = 0.9028–0.9981). The sensitivity of the model to the four primary parameters was analyzed to investigate the influence of model properties on the hydraulic and mechanical behavior. Results show that the calculation of volumetric strain is most sensitive to Young’s modulus (E), while the calculation of specific water volume is most sensitive to permeability (k). In addition, the sensitivity of the parameters changes with their value. Modeled results show that the porosity change significantly affects both hydraulic and mechanical behavior, even when soil undergoes relatively low deformation. Relative calculation error decreases notably after porosity change is considered (44.9% and 35.2% improvement in two different calculations). This study also finds that dynamic porosity affects the deformation energy of solids.