An Elastoplastic Constitutive Model for Grain Considering Moisture Content

Grain may undergo hygroscopic swelling during storage, and its stress–strain response under confinement may significantly amplify the lateral pressure on silo walls, posing a potential threat to structural safety. A reasonable characterization of the influence of moisture content on the stress–strain behavior of grain, along with an accurate estimation of the lateral pressure during moisture absorption, is crucial for ensuring the safety of grain storage facilities. In this study, within the framework of Critical State Soil Mechanics (CSSM), a novel constitutive model incorporating moisture content is developed to characterize the hygroscopic swelling of grain. The model introduces a volumetric strain formulation that explicitly decouples the effects of void ratio variation and particle deformation. Moisture-dependent normal compression lines and state parameter are incorporated to capture the effects of moisture content on strength. The proposed model accurately reproduces the stress–strain response under moisture variation and successfully predicts the amplification of lateral pressure during moisture absorption. This work provides a theoretical basis for more reliable structural assessment of silos operating in humid environments.