Specimen preparation methods significantly affect indoor sand soil's properties. A theoretical model was developed based on granular thermodynamics to describe the undrained shear characteristics of calcareous sand. We validated the model using specimens prepared through four different methods under various relative densities, stress paths, and confining pressures. The hardening index and granular temperature of this model effectively reflect the impact of specimen preparation methods on the strength characteristics of calcareous sand. The model successfully captured these differences in shear behavior resulting from four preparation methods by adjusting the hardening parameters. Furthermore, this model can accurately describe the influence of stress path changes on the mechanical responses of the calcareous sand granular system by incorporating the third elastic strain invariant.
