E3S Web Conf.
Volume 92, 20197th International Symposium on Deformation Characteristics of Geomaterials (IS-Glasgow 2019)
|Number of page(s)
|Discrete Element Modelling
|25 June 2019
Influence of stress anisotropy on stress distributions in gap-graded soils
Imperial College London, Civil and Environmental Engineering Department, London, United Kingdom
2 University of Glasgow, School of Engineering, Glasgow, United Kingdom
* Corresponding author: firstname.lastname@example.org
The behaviour of gap graded soils comprising non-plastic fines (sand or silt) mixed with a coarser sand or gravel fraction has received attention from researchers interested in internal instability under seepage loading (a form of internal erosion) as well as researchers interested in load:deformation responses. Skempton and Brogan  postulated that resistance to seepage induced instability depends upon the proportion of the overall applied stress that is transmitted by the finer fraction. Shire et al.  explored Skempton and Brogan’s hypothesis using DEM simulations to look at the proportion of the applied stress transmitted by the finer fractions (α) in ideal isotropic samples. They showed that at low fines contents (FC< FC*) the average stress transmitted by the finer grains is less than the applied stress (α<1), while for FC>FC+ the fines play a key role in stress transmission (α>1); for FC*<FC< FC+, α depends on the sample density. The current contribution describes a series of constant p’ DEM triaxial test simulations carried out to assess the evolution of stress heterogeneity with shearing. The simulation data generated indicate that a sample can transition from being fines dominated (with the fines transmitting a significant proportion of the applied stress and α ≥1) to coarse or sand- dominated (with α <1) as the material dilates during shear deformation. While α reduces as the samples dilate, the relationship between the α and the sample void ratio is non-trivial. The anisotropy of the coarse-coarse contact network exceeds the overall contact force anisotropy; this indicates that the deviator stress is transmitted through a strong force network passing through the coarse-coarse contacts supported by the fine-coarse contacts.
© The Authors, published by EDP Sciences, 2019
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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