Binary medium constitutive model of Cemented Sand and Gravel (CSG)

As a synthetic material, cemented sand and gravel (CSG) holds significant promise for application in dam construction. However, research on the mechanical properties and constitutive models of CSG remains limited. This study establishes a binary medium constitutive model for CSG based on triaxial test data obtained under varying gel content and confining pressure conditions, as well as the theoretical framework of continuum mechanics. The triaxial test results indicate that the stress-strain curve of CSG exhibits strain softening behavior. With increasing confining pressure, the volumetric strain curve transitions from initial volumetric shrinkage followed by volumetric dilatancy to complete volumetric shrinkage. The strain softening and dilatancy characteristics of CSG become more pronounced with higher gel content. In the proposed constitutive model, CSG are represented as a composite of a bonded element and a frictional element. The bonded element demonstrates linear elastic behavior, while the frictional element exhibits elastoplastic properties. Under external loading, the bonded element progressively degrades into the frictional element, with both elements sharing the load. To describe the interaction between the bonded and frictional elements within the representative volume element (RVE), the homogenization theory introduces failure rate and strain concentration coefficients, thereby capturing the evolution of internal structure and non-uniform strain distribution during loading. Comparisons between experimental and simulated curves confirm that the model accurately predicts the deformation characteristics of CSG, validating the rationality of the constitutive model.