Characteristics and modelling of coral sand particle breakage under principal stress axis rotation

To investigate the stress–strain characteristics and particle breakage laws of coral sand under the rotation of the principal stress axis—Objectives, the triaxial test and the principal stress axis rotation test were conducted on coral sand with varying consolidation confining pressures and compactness—Methods. Furthermore, a particle breakage model considering the irregularity and non-uniformity inherent in coral sand was established. The results show that: (1) Scanning electron microscopy (SEM) analysis and triaxial test demonstrates that the coral sand has strong non-coaxial characteristics. Both increased compactness and confining pressure enhance the strength of coral sand; (2) Coral sand undergoes shear expansion followed by gradual compression in triaxial shear, and demonstrates body shrinkage when its compactness is relatively high. The broken particles of coral sand are mainly large particles, small particles are less broken or not broken, and the disappearance of prism is the main type of particle breakage; (3) The form of particle breakage in coral sand under rotation of the principal stress axis is mainly grinding—Key Findings. The irregularity and non-uniformity of coral sand can be represented with the equivalent of non-coaxiality in the deformation and breakage process of the principal stress axis rotation, and a mathematical model has been established to characterize the breakage behavior of coral sand particles. Impressively, The model demonstrates high accuracy in predicting particle breakage under principal stress rotation (average error < 5 %).