Fabric evolution of granular assembly under K₀ loading/unloading

Abstract

SUMMARYThis study attempted to investigate the fabric evolution in K 0 loading/unloading. The work made use of a field simulator to control K 0 loading/unloading in large specimens prepared by air-pluviation. In each loading stage, wave velocities along various propagation directions were measured. On the basis of the theories of micro-mechanics and wave propagation, the microscopic parameters of the granular assembly were back calculated to investigate the fabric evolution of granular soil during K 0 loading/unloading.In this study, the Geometric fabric was modelled by fabric tensors of ranks 2 and 4. The comparison of calibrated results using ranks 2 and 4 revealed the advantage of the usage of rank-4 fabric tensor in modelling fabric evolution in spite of its complexity.By comparing relative magnitudes of vertical and horizontal components of geometric fabric, it was demonstrated that relative constraint in lateral directions increased during K 0 -unloading in order to maintain a K 0 condition. It revealed that fabric evolution was responsible for a higher K 0 in unloading than K 0 in loading.

Mechanical properties of granular materials: A variational approach to grain‐scale simulations

“…Tracking hysteresis via grain-scale parameters can be done quantitatively using the fabric tensor [37]. Qualitatively, we observe that these abrupt changes were correlated to relatively large displacements experienced by several grains.…”

“…The abrupt change in the slopes is associated with variations in the complex network of contacts ("fabric") and contact forces. Some of these microstructural variations are irreversible, contributing to the hysteretic response observed in experiments [37]. This hysteresis is evident in Figure 3 as different loading and unloading curves.…”

K0 estimation in level granular soil from anisotropic wave velocities on the basis of micromechanics

“…in which the tensor D i 1 ÁÁÁi n is called the 'fabric tensor of the third kind' of rank n: Liou and Pan [19] derived the correlations between the coefficients of fabric tensor up to rank 4 for a transversely isotropic granular assembly and used those correlations to evaluate the geometric fabric of the assembly on the basis of micromechanics. The contact-force distribution (i.e.…”