考虑颗粒破碎的粗粒土剪胀性统一本构模型

粗粒土作为无黏性散粒状材料具有状态依赖特性，土体的剪切特性受密度和应力水平影响。易破碎是粗粒土的另一个特点，颗粒破碎影响粗粒土的剪胀、内摩擦角、峰值强度和渗透系数。为了能够准确地描述粗粒土的应力-应变关系，采用初始状态参量描述粗粒土的内部状态，根据三轴试验数据建立考虑颗粒破碎耗能的应力-应变关系，采用相关联流动法则推导考虑颗粒破碎的粗粒土剪胀性“统一本构模型”，并建立初始状态参量与模型参数之间的关系。所建立的统一本构模型既考虑了颗粒破碎对剪胀、内摩擦角的影响，又考虑了剪切特性对土体初始状态的依赖。采用变异粒子群算法拟合试验曲线，确定模型参数。模型计算结果能够很好地拟合试验曲线。采用同一组参数对假定的初始状态进行模拟计算，计算结果表明，模型能够模拟不同初始密度和应力水平下粗粒土变形的一般规律。

Dilatancy unified constitutive model for coarse granular aggregates incorporating particle breakage

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.