Abstract: Based on the triaxial experimental results of parallel specimens loaded under various axial strains, the intermediate particle breakage process of a coral sand is investigated, and the limitations of the energy-based breakage correlation and the popular stress-based Hardin breakage model are discussed. In order to reveal the characteristics of its intermediate accumulating process more conveniently, the particle breakage is decomposed into two parts based on the loading mechanisms: (1) compression-induced particle breakage associated with the increase of mean effective stress, and (2) shear-induced particle breakage related to the change of shear stress ratio. The amount of compression-induced particle breakage can be correlated to the current stress state. The accumulating rate of shear-induced particle breakage depends on both the shear strain and the accumulated amount of particle breakage during the past stress history. Two mathematical models are presented for the two particle breakage parts respectively, and the effectiveness of the two models is demonstrated by simulating the triaxial test results of the coral sand.