Abstract Granular materials can develop two different failure modes following their initial density and the loading path: a localized mode, generally characterized by shear bands, and a diffuse mode without any macroscopic localized bands. In fact detailed analyses of experiments by tomography, of finite element computations and more recently of discrete element models (DEM) simulations show that two different localized objects co-exist at two different scales: a network of meso-slip lines appearing from the very beginning of deviatoric loading and a few macro-shear bands when approaching limit stress states. This paper aims to compare and analyze these two localized patterns, based on DEM results obtained for a given class of loading paths applied to several 2D numerical granular samples with different initial densities. It is first shown that void ratios and granular meso-structures are the same inside shear bands and for the whole samples in case of diffuse failure. Then slip lines and shear bands are shown to be distinct localized objects. Eventually, the questions of why and how the network of meso-slip lines is sometimes bifurcating into a set of few macro-shear bands are discussed.

中文翻译：

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滑移线与剪切带：两种相互竞争的定位模式

摘要 颗粒材料可以根据其初始密度和加载路径发展两种不同的失效模式：局部模式，通常以剪切带为特征，以及没有任何宏观局部带的扩散模式。事实上，通过断层扫描、有限元计算和最近的离散元模型 (DEM) 模拟对实验的详细分析表明，两个不同的局部物体在两个不同的尺度上共存：从一开始就出现的细观滑移线网络接近极限应力状态时的偏载和一些宏观剪切带。本文旨在比较和分析这两种局部模式，基于对给定类别的加载路径获得的 DEM 结果，该结果应用于具有不同初始密度的几个二维数值颗粒样本。首先表明，在扩散破坏的情况下，剪切带内部和整个样品的空隙率和粒状细观结构是相同的。然后滑移线和剪切带显示为不同的局部物体。最后，讨论了为什么以及如何将细观滑移线网络有时分成一组少数宏观剪切带的问题。