Abstract:

The coarse granular aggregates equipped the state-depended characters is a kind of cohesiveless granular materials, of which stress-strain relationship depends on the density and stress level. The coarse granular aggregate is fragile, which is another character of it. Particle breakage of coarse granular aggregates modifies its structure directly, influencing its dilatancy, friction angle, strength and permeability. In order to accurately describe stress-strain relationship of coarse granular aggregates, the initial state parameter is applied to represent the interior state of the soil. The stress-strain relationship incorporating particle breakage energy is established according to triaxial test results, on which the dilatancy unified constitutive model of coarse granular aggregates is developed with associated plastic flow rule. The relationship between parameters of the current model and initial state parameter is developed. The unified constitutive model is developed, which incorporates not only the particle breakage influence exerting on dilatancy and friction angle, but also the dependence of stress-strain relationship on initial state. The parameters of model are determined by mutation particle swarm optimization algorithm, on which the triaxial test results are well simulated. The simulations are applied according to presumed initial state with the parameters determined above; the result indicates that the current model could simulate the transformation of coarse granular aggregates at various initial densities and stress levels.

Key words: unified constitutive model, state-depended, particle breakage, breakage energy, mutation particle swarm optimization algorithm