p=constant compression on loose Hostun sand: The case of an anisotropic response

TL;DR

This study investigates the response of loose Hostun sand under constant mean pressure compression, revealing anisotropic behavior even at small stresses, challenging traditional isotropic models in soil mechanics.

Contribution

It demonstrates that the sand's response is not isotropic at small stresses, questioning the unicity of classical phase space trajectories in soil mechanics.

Findings

Material response is anisotropic at small deviatoric stress.

Isotropic behavior observed during constant volume compression.

Challenges the sufficiency of a 3D phase space in soil modeling.

Abstract

Experimental data from axially symmetric compression test at constant mean pressure p on Hostun sand from Flavigny experiments on loose sands are used to study the validity of an "isotropic" modelling at different densities . It is found that the material response is not isotropic even at small deviatoric stress. As an "isotropic" behaviour is found for compression test at constant volume on the same sand, this new result questions the unicity of the trajectory in the classical phase space of soil mechanics (q,p,v), with q being thed deviatoric stress, v the specific volume. This asks whether the space shall be taken larger than 3d or not. Pacs # : 5.40 ; 45.70 ; 62.20 ; 83.70.Fn