Effects of morphological gene decay and mutation on the micro–macro mechanical behaviours of granular soils

Particle morphology is multi-scale in nature. To investigate the effects of particle morphology at a specific length scale on the macro–micro mechanical behaviours of granular soils, morphological gene decay and mutation was incorporated into discrete-element method (DEM) simulations through spherical harmonic-based principal component analysis. All DEM samples were subjected to axial compression and constant confining stress. The macro-scale and grain-scale behaviours of the granular assembly were investigated. It was found that particle morphology shows significant effects on macro-scale behaviours including initial stiffness, peak stress ratio, volumetric contraction and dilation, and shear band formation, as well as grain-scale behaviours including coordination number, particle rotation and granular skeleton sustaining the major contact force chains. Among the different length scales, local roundness contributes the most to stress ratio, volumetric strain and particle coordination number, while general form contributes the most to shear strain, particle rotation and fabric structure. Another interesting finding was that the particle morphological effects are well reflected in the granular skeleton sustaining the major contact force chains, which is featured with a strong variation of the degree of particle shape irregularity among different kinds of gene-mutated samples.