Particle breakage evolution during cyclic triaxial shearing of a carbonate sand

Abstract

Particle breakage of carbonate sand under cyclic loading might be of interest in some circumstances, while few research results were reported. Drained and undrained cyclic triaxial tests terminated at different loading cycles were conducted on a carbonate sand to investigate the evolution characteristics of particle breakage during cyclic shearing. Considerable breakage was observed after successive cyclic triaxial shearing at moderate confining pressure levels (≤200 kPa). Abrasion of surface asperities and small sharp edges was found to be the primary pattern of particle breakage and the particle size distribution after cyclic shearing showed an increased mass content of fine particles. In drained cyclic tests with constant confining pressure and cyclic stress amplitude, particle breakage appeared to accumulate at a decreasing rate with increasing loading cycles, and the development of particle breakage with loading cycles can be fitted by a logarithmic equation. In undrained cyclic tests, particle breakage exhibited more complicated accumulation patterns because the effective confining pressure and cyclic strain amplitude varied greatly. A cycle-by-cycle incremental breakage evolution model was established, and the model revealed that the incremental breakage generated in subsequent loading cycles decreases with accumulated particle breakage and increases with increasing effective confining pressure and cyclic shearing intensity. The model was validated by comparing the model predictions with the particle breakage evolution observed during undrained cyclic triaxial tests.