Study on the evolution of critical state and constitutive modeling for calcareous sand under anisotropic consolidation paths

Calcareous sand is the primary foundation material used for reef construction in the South China Sea, where it is subjected to construction loads along various consolidation stress paths. Understanding the critical state evolution of calcareous under various consolidation paths is essential for developing an accurate constitutive model. By conducting triaxial consolidation drained shear tests with four relative densities and four consolidation paths, the intrinsic relationship between particle breakage and the evolution of critical state line under varying consolidation stress paths are investigated. The results indicate that, as the effective principal stress ratio decreases from 1.00 to 0.45, the relative particle breakage rate of calcareous sand decreases, the corresponding critical state void ratio increases, and the slope of the critical state line decreases, indicating a counterclockwise rotation trend. Meanwhile, a quantitative relationship between the effective principal stress ratio, relative breakage rate, and critical state void ratio under different consolidation paths was established. The predicted values of the critical state void ratio were approximately 0.8 to 1.2 times the measured values. This relationship was incorporated into the state-dependent dilatancy equation for sandy soils, enabling the development of a state-dependent constitutive model for calcareous sand that accounts for the influence of consolidation paths. The proposed model accurately describes the shear characteristics of calcareous sand under varying consolidation paths, densities, and stress levels. Differences in particle breakage caused by varying consolidation paths and consolidation pressures are the primary reason for the rotation of the critical state line in calcareous sand after shearing.