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DEM assessment of scaling laws capturing the grain size dependence of yielding in granular soils

机译：DEM评估尺度法则，捕获粒状土壤中产量的粒度依赖性

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摘要

Experimental evidences show that the pressure at which granular soils exhibit a sharp increase of their compressibility depends on the size of the particles that constitute their skeleton, thus reflecting the role of microscale fracture events on the macroscopic compression of granular systems. In this paper, the distinct element method (DEM) is used to test the validity of scaling laws relating the macroscopic energy at which the grains of a soil matrix crush collectively to the energy at which individual grains subjected to diametrical compression undergo tensile fracture. Oedometric compression tests on uniformly graded specimens with different values of particle size have been simulated by considering two deterministic fracture models and a probabilistic criterion based on the Weibull weakest link theory. It has been shown that the constants of proportionality between grain-scale and assembly-scale crushing thresholds depend considerably on the statistical variability of the particle strength, and that a larger variability exacerbates the departure between the scaling constants pertaining to deterministic and probabilistic models. Nevertheless, for the chosen set of initial conditions and loading paths, the simulations have suggested the applicability of a proportional scaling between the energy stored in the assembly at the moment of yielding and that required to fracture a single grain. In particular, the simulations revealed that the scaling constants relating the microscopic and macroscopic energy thresholds fall within a rather narrow range and do not depend significantly on the grain size. The Breakage Mechanics theory has been used to further explore such connection between length scales, finding a good agreement between the DEM simulations and the yielding stress computed by the theory whenever its parameters were defined on the basis of the scaling constants computed from the DEM model. These results confirm the interplay between the statistical variability of the particle strength and the grain size dependence of the yielding pressure, stressing at the same time the usefulness of energy scaling arguments in incorporating the effect of micro-scale fracture events into continuum models.
机译：实验证据表明，粒状土壤的可压缩性急剧增加的压力取决于构成其骨架的颗粒的大小，从而反映了微观断裂事件对粒状系统宏观压缩的作用。在本文中，使用离散元方法（DEM）来检验尺度定律的有效性，该尺度定律将土壤基质颗粒共同破碎的宏观能量与承受径向压缩的单个颗粒进行拉伸断裂的能量相关联。通过考虑两个确定性断裂模型和基于威布尔最弱连接理论的概率准则，对具有不同粒径值的均匀梯度试样进行了测压试验。已经表明，晶粒度和装配度破碎阈值之间的比例常数在很大程度上取决于颗粒强度的统计变异性，并且较大的变异性加剧了与确定性模型和概率模型有关的缩放常数之间的偏离。然而，对于所选的一组初始条件和加载路径，模拟表明在屈服时存储在组件中的能量与破碎单个晶粒所需的能量之间成比例的缩放比例是适用的。特别地，模拟显示与微观和宏观能量阈值相关的缩放常数落在相当窄的范围内，并且不显着取决于晶粒尺寸。断裂力学理论已被用于进一步探索长度标尺之间的这种联系，只要根据从DEM模型计算出的标度常数定义了其参数，DEM模拟与该理论计算出的屈服应力之间就可以找到很好的一致性。这些结果证实了颗粒强度的统计变异性与屈服压力的晶粒尺寸依赖性之间的相互作用，同时强调了能量尺度论证在将微观尺度断裂事件的影响纳入连续模型中的有用性。

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  • 来源
    《Granular matter》 |2016年第3期|36.1-36.15|共15页
  • 作者

    Cil Mehmet B.; Buscarnera Giuseppe;

  • 作者单位

    Northwestern Univ, Dept Civil & Environm Engn, 2145 Sheridan Rd,Tech A236, Evanston, IL 60208 USA;

    Northwestern Univ, Dept Civil & Environm Engn, 2145 Sheridan Rd,Tech A124, Evanston, IL 60208 USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Particle crushing; Grain fracture; Yielding; Constitutive modeling;

    机译：颗粒破碎;颗粒断裂;屈服;本构模型;

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