Using geophysical data to quantify stress-transmission in gap-graded granular materials

Otsubo, M., Kuwano, R., O'Sullivan, C. and Shire, T. (2022) Using geophysical data to quantify stress-transmission in gap-graded granular materials. Geotechnique, 72(7), pp. 565-582. (doi: 10.1680/jgeot.19.p.334)

Abstract

The behaviour of gap-graded granular materials, i.e. mixtures of coarse and cohesionless finer grains having a measurable difference in particle size, does not always confirm to established frameworks of sand behaviour. Prior research has revealed that the role of the finer particles on the stress-strain response, liquefaction resistance, and internal stability of non-cohesive gap-graded soils is significant and complex, and highly dependent on both the volumetric proportion of finer particles in the material and the coarse-particle to finer-particle size ratio. Quantifying the participation of the finer particles on the stress transmission and overall behaviour is central to understanding the behaviour of these materials. However, no experimental technique that can directly quantify the contribution of finer particles to the overall behaviour has hitherto been proposed. This paper explores to what extent the participation of finer particles can be assessed using laboratory geophysics, recognizing that granular materials act as a filter to remove the high frequency components of applied seismic / sound waves. Discrete element method simulations are performed to understand the link between particle-scale stress transmission and the overall response observed during shear wave propagation. When the proportion of finer particles is increased systematically both the shear wave velocity (VS) and low-pass frequency (flp) increase sharply once a significant amount of the applied stress is transferred via the finer particles. This trend is also observed in equivalent laboratory experiments. Consequently, the flp–VS relationship can provide useful insights to assess whether the finer particles contribute to stress transmission and hence the mechanical behaviour of the gap-graded materials.

• Item Type: Articles
• Additional Information: This work was supported by the special fund of Institute of Industrial Science, The University of Tokyo, and by JSPS KAKENHI Grant Number 19K15084.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Shire, Dr Thomas
• Authors: Otsubo, M., Kuwano, R., O'Sullivan, C., and Shire, T.
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment
• Journal Name: Geotechnique
• Publisher: ICE Publishing
• ISSN: 0016-8505
• ISSN (Online): 1751-7656
• Published Online: 26 January 2021
• Copyright Holders: Copyright © ICE Publishing
• First Published: First published in Geotechnique 72(7):565-582
• Publisher Policy: Reproduced in accordance with the publisher copyright policy