Presented is a study on the geometrical characteristics of sand particles and the mechanical behavior of sand material under external loading. Based on computed tomography technique, a reconstruction method of granular particles was developed and used to build a database of 3D geometrical models for sand particles. The studied sand particles showed good regularities in morphological characteristics and thus were suitable to be used for the random generation of numerical samples. DEM tests using realistically shaped particles were proven to better simulate the mechanical behavior of the sample during elastoplastic loading stage, which was an issue for the simplified spherical particles. The generation, extension, and breakage of the force chains controlled the strain softening behavior of sands. Anisotropy analysis using the spherical harmonic series showed that the evolution of anisotropy directions and parameters corresponded well with the macroscopic mechanical behavior of the material. Pore volume computation based on Voronoi diagram was performed to illustrate the formation and evolution of localized shear zone. The mesoscopic analysis showed that particle shape significantly influences the mechanical behavior of sands and thus should be properly modeled in numerical simulations.

中文翻译：

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使用逼真的粒子模型的3D离散元方法研究砂土的力学行为

提出了在外部载荷作用下砂粒的几何特征和砂料力学行为的研究。基于计算机断层摄影技术，开发了一种颗粒状颗粒的重建方法，并将其用于建立砂粒的3D几何模型数据库。研究的砂粒在形态特征上显示出良好的规律性，因此适合用于数值样本的随机生成。实践证明，使用逼真的形状的颗粒进行DEM测试可以更好地模拟样品在弹塑性加载阶段的力学行为，这对于简化的球形颗粒而言是一个问题。力链的产生，延伸和断裂控制了砂土的应变软化行为。使用球谐序列进行各向异性分析表明，各向异性方向和参数的演变与材料的宏观力学行为非常吻合。进行了基于沃罗诺伊图的孔体积计算，以说明局部剪切带的形成和演化。介观分析表明，颗粒形状显着影响砂的力学性能，因此应在数值模拟中正确建模。