Fabric anisotropy underpins the mechanical response of granular soils pertaining to a wide range of practical geotechnical applications. This paper presents a multiscale computational study on a strip footing resting on an anisotropic soil foundation. The focus of this study is placed on examining the cross-scale links of key grain-scale mechanisms in the soil that underscore interesting macroscopic observations of the footing problem over a full loading range from peak to large deformation regimes until its failure. We employ a hierarchical coupling of Material Point Method and Discrete Element Method (MPM-DEM). Mesoscale ensembles consisting of elliptical particles with specific alignments to represent bedding planes in anisotropic soils are generated. They are embedded into the material points of the MPM and serve as Representative Volumetric Elements (RVEs) with solutions by DEM to extract nonlinear material responses in solving the footing as a boundary value problem that may undergo large deformation to failure. The study confirms experimental observations that the bearing capacity of the strip footing decrease with the bedding angle $\alpha$. It shows that ignoring fabric anisotropy for soil may lead to a significant overestimation or underestimation of the bearing capacity in extreme cases. The final failure patterns for all anisotropic cases feature general failure modes with two major slip surfaces, and they are predominantly in an asymmetric manner except the horizontal bedding case and the isotropic case. The degree of asymmetry in the failure pattern shows a correlation with the bedding angle. These observed features are further corroborated with microstructural analyses on the evolution of different sources of fabric anisotropy in slip surface.

结构各向异性支持与广泛的实际岩土工程应用相关的粒状土壤的机械响应。本文介绍了搁置在各向异性土壤基础上的条形基础的多尺度计算研究。本研究的重点是检查土壤中关键颗粒尺度机制的跨尺度联系，这些联系强调了在从峰值到大变形状态直至其失效的整个加载范围内对基础问题的有趣宏观观察。我们采用了材料点法和离散元法 (MPM-DEM) 的分层耦合。生成由具有特定排列的椭圆粒子组成的中尺度集合，以表示各向异性土壤中的层理平面。它们被嵌入到 MPM 的材料点中，并作为代表性体积元素 (RVE) 使用 DEM 的解决方案来提取非线性材料响应，以将基础作为边界值问题解决，该问题可能会经历大变形导致失效。该研究证实了实验观察结果，即条形基础的承载力随着层理角度的增加而降低$\alpha$. 这表明，在极端情况下，忽略土壤的织物各向异性可能会导致承载力的显着高估或低估。所有各向异性情况的最终破坏模式都具有具有两个主要滑移面的一般破坏模式，除水平层理情况和各向同性情况外，它们主要以非对称方式出现。破坏模式的不对称程度显示出与层理角度的相关性。这些观察到的特征通过对滑动表面中不同来源的织物各向异性演变的微观结构分析得到进一步证实。