Particle breakage characteristics and grading evolution of calcareous sand under various stress paths

Stress path is a key factor affecting the particle breakage of calcareous sand. In this study, the effects of stress path variations on calcareous sand particle breakage were investigated through triaxial compression tests across four distinct stress paths. Additionally, the gradation evolution of calcareous sand during particle breakage was analyzed. Furthermore, the correlation between the total input energy and characteristic particle size was investigated through energy dissipation analysis. The results indicated that the relative breakage index increases gradually with an increase in the maximum deviatoric stress and final volumetric strain, irrespective of the stress path. However, the dilatancy of calcareous sand is related to the relative breakage index as well as the stress path. Notably, the relationship between the relative breakage index and the total input energy can be represented using a power function. A gradation evolution model was formulated based on the results of energy dissipation analysis, and its validity was verified. The results confirmed the model's effectiveness in predicting the particle breakage evolution in both single-gradation and continuous-gradation calcareous sand specimens, accounting for the effects of the various stress paths.