Particle Breakage and Deformation Behavior of Carbonate Sand under Drained and Undrained Triaxial Compression

The results of a series of drained and undrained triaxial compression tests terminated at various axial strains were reported to show the gradual accumulation process of particle breakage of a carbonate sand during triaxial compression. A breakage model, which relates the particle breakage rate to the accumulated amount of particle breakage and current effective confining pressure, was established based on the drained test results. The effectiveness of the breakage model was validated by successful simulation of the undrained test results using the same parameters calibrated from the drained tests. Incorporating the breakage model into the critical state framework, a constitutive model for the carbonate sand considering particle breakage was established through a critical state surface in the space of void ratio, mean effective stress, and relative breakage, and a variable critical state stress ratio decreasing with increasing breakage. The comparison of the test results and the model simulations with and without breakage revealed the way in which the evolution of particle breakage affects the deformation behavior. (C) 2020 American Society of Civil Engineers.