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土体的物理力学特性受到颗粒尺度及其级配的强烈影响,具有显著的颗粒尺度效应。文中采用天然黏土和商品石英砂,制备具有不同颗粒粒径和体分比的一系列三轴抗剪试样,通过不固结不排水和固结不排水三轴抗剪试验,测得了应力应变关系曲线以及剪应力屈服强度,基于试验结果对土体力学特性的颗粒尺度效应进行分析;同时,引入胞元土体模型,对土体力学特性颗粒尺度效应的物理机制进行解释。实验结果表明,随着土体中砂粒体分比增加和粒径的减小,土体的变形特性明显增强,其剪应力屈服强度也随之显著提高;砂粒的体分比对变形和强度颗粒尺度效应的影响比粒径的影响更为显著;胞元土体模型解释了实验结果的颗粒尺度效应的物理机制。
The physical and mechanical properties of soils are strongly influenced by the grain size and its gradation, with significant grain-scale effects. In this paper, a series of triaxial shear specimens with different particle size and volume fraction were prepared by natural clay and commercial quartz sand. The stress-strain curves were obtained by non-drained and consolidated undrained triaxial shear tests The relationship curve and the yield stress of shear stress are presented. Based on the test results, the particle size effect of soil mechanics is analyzed. At the same time, the cellular model of soil mass is introduced to explain the physical mechanism of particle scale effect of soil mechanics. The experimental results show that with the increase of sand body fraction and the decrease of particle size, the deformation characteristics of soil significantly increase, and the yield stress of the soil significantly increases. The ratio of sand body fraction to deformation and strength particles The effect of scale effect is more significant than that of particle size. The cell-soil model explains the physical mechanism of the particle-scale effect of the experimental results.