结核质量分数及粒径对钙质结核土动弹性模量的影响

钙质结核土具有独特的物质组成和结构,其土动力学方面的研究较少。文章开展了一系列含有不同粒径和质量分数结核的钙质结核土试样的动三轴试验,研究结核的存在对钙质结核土动弹性模量的影响。试验结果表明:随着循环次数的增加,土体动弹性模量先迅速降低,而后降低幅度随动应变的增大而逐渐减小;随着结核粒径或质量分数的增大,土体动弹性模量随之增大,土体抵抗动荷载作用变形的能力越强。采用颗粒流PFC2D对钙质结核土的动三轴试验进行数值模拟,模拟结果表明在循环荷载作用下,结核明显阻滞了其周围细粒的变位,结核及其周围产生明显应力集中,形成土体“骨架”,从微观上解释了结核的存在对土体动弹性模量的影响和作用。该研究成果为钙质结核土动力学研究奠定了基础,对其他类似粗粒-细粒结构土体的动力学研究具有重要的参考价值。

Cohesive soil containing calcareous nodules has unique material composition and structure, and there has been relatively little research on its soil dynamics. In this paper, a series of dynamic triaxial tests of cohesive soil containing calcareous nodules with different particle sizes and mass fractions of nodules were carried out to study the influence of the presence of nodules on the dynamic elastic modulus of cohesive soil containing calcareous nodules. The test results show that with the increase of the number of cycles, the dynamic elastic modulus of the soil decreases rapidly at first, and then the reduction amplitude gradually decreases with the increase of dynamic strain. With the increase of particle size or mass fraction of nodules, the dynamic elastic modulus of the soil increases, and the ability of the soil to resist deformation under dynamic loads becomes stronger. Particle flow code (PFC2D) was used to numerically simulate the dynamic triaxial test of cohesive soil containing calcareous nodules. The simulation results indicate that under cyclic loading, the nodules significantly hinder the displacement of fine particles around them, and significant stress concentration is generated around the nodules, forming a "skeleton" of the soil. From a microscopic perspective, the influence and role of the presence of nodules on the dynamic elastic modulus of the soil are explained. The research results have laid the foundation for the dynamic research of cohesive soil containing calcareous nodules, and have important reference value for the dynamic research of other similar structured soils.