Shear band evolution phenomena in direct shear test modelled with DEM

A direct shear test is widely used in the geotechnical engineering field. It is an easy and quick test to measure the shear properties of soil. This test often replaces more expensive and difficult tri-axial shear test. Despite that the direct shear test is known and used for a long time, it is still not well investigated at the grain scale. This paper deals with the micro behaviour of the cohesionless sand inside the direct shear box during a geotechnical test. Numerical calculations were performed with open-source discrete code YADE. The full 3D model was used, in order to eliminate some non-physical phenomena. The numerical stress-strain curve was directly compared with the laboratory results and good agreement was obtained. The focus was on the shape of the localized zone, the properties of this zone and its behaviour. The movement of the individual grains was studied. In our analysis, the stresses were also taken into consideration. The conclusions were validated on tests with different initial void ratio (dense or loose material) and with different vertical pressure. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

The direct shear test is widely used in geotechnical engineering for measuring the shear properties of soil. This study focuses on the micro behavior of cohesionless sand in direct shear box during geotechnical tests, using numerical simulations and laboratory comparisons to investigate its properties.