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荷载作用下粒状岩土材料的颗粒破碎改变了粒径分布,从而影响其力学特性。为了揭示应力水平对颗粒破碎的影响规律,利用一系列高压应力下的侧限压缩试验研究钙质砂和石英砂的压缩变形、应力–应变关系、粒径分布的演化和颗粒破碎特性。在此基础上,建立描述粒状岩土材料的应力水平与孔隙比、体应变、相对破碎率等相关关系的数学模型。研究结果显示:无论是钙质砂还是石英砂,随着应力水平的增加,一旦颗粒破碎增长致使砂粒趋向分形分布,体应变与相对破碎率的比值将保持恒定。恒定比值意味着基于体应变就可估算相对破碎率,其数值为石英砂大于钙质砂。如果颗粒分布发展至分形分布,其孔隙比、体应变、相对破碎率的增量随应力水平的变化规律,可以用形式统一的数学模型表达。基于试验获得的模型参数,该模型可用于预测颗粒在分形分布阶段的相对破碎率。
Particle breakage of granular geomaterials under load changes the particle size distribution and thus affects its mechanical properties. In order to reveal the influence of stress level on the particle breakage, a series of compression tests under high compressive stress were used to study the compressive deformation, stress-strain relationship, the evolution of particle size distribution and the particle crushing properties of calcareous sand and quartz sand. On this basis, a mathematical model describing the correlation between stress level and porosity ratio, volumetric strain, relative breaking rate and so on is established. The results show that both the calcareous sand and the quartz sand, as the stress level increases, the proportion of the body strain to the relative crushing rate will remain constant once the particles are broken and grow, resulting in the fractal distribution of the sand. A constant ratio means that the relative crushing rate can be estimated on the basis of the volumetric strain, which is greater than that of the quartz sand. If the particle distribution develops into a fractal distribution, the variation of void ratio, bulk strain and relative fragmentation rate with stress level can be expressed by a unified mathematical model. Based on the experimental model parameters, the model can be used to predict the relative fragmentation rate of the particles in the fractal distribution.