Abstract
Coral sand is a typical crushable granular soil, and its mechanical properties are not only state-dependent but also significantly affected by particle breakage. The classical state-dependent model only considers the two state variables, i.e., void ratio and confining pressure. To introduce the initial gradation as the third state variable into the constitutive model, a series of triaxial consolidation drainage tests under various gradations, relative densities and confining pressures were conducted on the coral sand from South China Sea. Experimental results demonstrated that the initial gradation and confining pressure have a significant effect on the particle breakage of coral sand. The critical state line of coral sand in the e-(p'/pa)ξ plane can be expressed as a straight line, and the intercept eΓ is related to both the initial void ratio and the initial gradation, while the slope λc is only correlated with the initial gradation. A three state variables-dependent constitutive model considering the effect of particle breakage is developed and validated in this paper, and the simulation results show that the model can well predict the stress-strain behavior of coral sand under various initial gradations, relative densities and confining pressures by using only one set of model parameters.