Measuring mechanical anisotropy on geogrid reinforced soil using a cubical triaxial apparatus

Abstract

This work describes the main findings of an experimental program focused on the characterization of the mechanical anisotropy of a reinforced cohesive soil using a cubical triaxial apparatus. Several authors have studied the influence of geometry, type, number and arrangement of reinforcement layers on the mechanical behaviour of reinforced soils, mainly dedicated to evaluate the improvement of stiffness and strength. The influence of anisotropy and principal intermediate stress has not been addressed. Conventional triaxial cell (axisymmetric) and pull-out tests are the most common type of devices used in the present studies. The implementation of an experimental program using a cubical triaxial apparatus allows us to consider all the aspects mentioned before, mainly those related to an anisotropic characterization and the principal intermediate stress influence on stress-strain and strength behaviour. Results obtained in this work, show that reinforced soil is a cross-anisotropic material, and its stress-strain and strength behaviour is strongly influenced in sectors I (lode angle between 0° and 60°) and II (lode angle between 60° and 120°) of the octahedral plane. Thus, a complete characterization of geogrid reinforced soil can be made selecting an appropriate set of stress paths in the cubical apparatus.