Abstract: Numerous experimental studies indicate that particle breakage alters the grain size distribution curve of calcareous sand, thereby affecting its mechanical behaviors. Consequently, investigating the particle breakage characteristics of calcareous sand and establishing a corresponding breakage evolution model are of critical importance. First, a series of isotropic consolidation and triaxial compression tests were conducted under various loading paths, confining pressures, and axial strains to systematically explore the influence of these factors on particle breakage in calcareous sand. Next, the intrinsic relationships among particle breakage, mean effective stress, and stress ratio were analyzed to quantitatively assess their combined influence on particle breakage within a unified theoretical framework. Finally, a novel particle breakage evolution model was proposed by integrating the experimental findings with an analysis of the Hardin model’s strengths and limitations. The model includes the derivation of the breakage equipotential surface. The model comprises only three parameters, facilitating straightforward calibration and ensuring clear physical interpretations. Furthermore, the model's validity and robustness were rigorously validated through triaxial tests on calcareous sand and other crushable granular materials.

Key words: calcareous sand, triaxial test, particle breakage evolution, loading path, breakage contour