A constitutive model for Cemented-Sand-Gravel (CSG) materials based on strength characteristics

As a novel dam type with numerous advantages, the cemented sand and gravel (CSG) dam is increasingly crucial in water conservancy engineering construction. Extensive triaxial shear tests were conducted on specimens with varying confining pressures and gel contents to investigate the intricate mechanical properties of the CSG. Subsequently, a suitable strength criterion and constitutive model for CSG were established. The results indicated that (1) CSG exhibits certain cementation and structural characteristics, displaying significant strain softening, strong shear dilatancy, and other macroscopic mechanical properties. (2) A shear strength criterion based on binary medium theory was developed to describe strength evolution in different gel contents. (3) The shear strength criterion was judiciously transformed into the constitutive model's shear yield surface while considering the material's tensile properties based on the modified Cam-Clay model to obtain the volumetric yield surface. Additionally, the constitutive model focuses on delineating strain softening and strong shear dilatancy of CSG. (4) The stiffness matrix of the constitutive model was derived under general stress conditions with proven good fitting effects during triaxial shear testing of CSG. These findings provide enhanced theoretical guidance for stress-deformation calculations related to CSG dams.