Effect of morphological gene mutation and decay on energy dissipation behaviour of granular soils

Abstract

目的 本文旨在探讨不同尺度颗粒形貌特征对于砂土应力-应变以及能量耗散行为的影响。 方法 1. 通过同步X射线计算断层扫描实验,提取高精度的真实颗粒形貌,并通过三维点云表征;2. 通过基于球谐分析的主成分分析方法,构建不同尺度下颗粒形貌的突变与衰减;3. 通过离散单元法仿真,模拟不同形貌试件的三轴剪切过程,并进一步讨论不同尺度颗粒形貌对于颗粒材料应力-应变以及能量耗散行为的影响。 结论 1. 通过比较较松散和较密实的试件,发现对于较松散试件,颗粒形貌对颗粒材料的初始刚度、应力-应变、体积应变和摩擦能量耗散等响应的影响更为明显;2. 对于不同尺度下的颗粒形貌,局部圆度较长径比对颗粒材料宏观响应的影响更大;3. 颗粒材料的能量耗散行为由颗粒形貌和初始孔隙率共同决定。 In this paper, the X-ray micro-computed tomography (X-ray µCT), spherical harmonical-based principal component analysis (SH-PCA), and discrete element method (DEM) were incorporated to generate virtual samples with morphological gene mutation at different length scales. All samples were subjected to axial compression and constant confining stress. The effects of multiscale particle morphology on the stress-strain and energy storage/dissipation responses of granular soils were investigated. It is found that: (a) the effects of particle morphology on the initial stiffness, stress-strain, volumetric strain, and frictional energy dissipation behaviours are more pronounced for looser samples than for denser ones; (b) among different length scales, the particle morphology at the local roundness-level outperforms the one at the general form-level in dictating the macro-scale responses of granular soils; (c) the energy dissipation of a granular assemblage is a result of competition between particle morphology and initial void ratio.