Determination of the equivalent intergranular void ratio - Application to the instability and the critical state of silty sand

Trung-Kien Nguyen,Nadia Benahmed,Pierre-Yves Hicher

doi:10.1051/epjconf/201714002019

Trung-Kien Nguyen, Nadia Benahmed + Show 1 more

Open Access

https://doi.org/10.1051/epjconf/201714002019

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Abstract

This paper presents an experimental study of mechanical response of natural Camargue silty sand. The analysis of test results used the equivalent intergranular void ratio instead of the global void ratio. The calculation of equivalent intergranular void ratio requires the determination of parameter b which represents, physically, the fraction of active fines participating on the chain forces network, hence the strength of the soil. A new formula for determining the parameter b by using an approach based on the coordination number distribution and probability calculation is proposed. The validation of the developed relationship was done through back-analysis of published datasets in literature on the effect of fines content on silty sand behavior. It is shown that the equivalent intergranular void ratio calculated with the b value obtained by the new formula is able to provide strong correlation to not only the critical state of but also the onset of instability of various silty sands, in different terms as peak deviator stress, peak stress ratio or cyclic resistance. Therefore, it is suggested that the use of the equivalent void ratio concept and the new b calculating formula is highly desirable in predicting of the silty sand behavior.

Highlights

The effect of fines content is an important parameter to take into account when evaluating the mechanical behavior of silty sand since it is widely encountered in nature
In order to take into account either active and inactive fine particles, a new density variable was proposed: the equivalent intergranular void ratio which is calculated as follows: e (1 b) f e*
It is interesting to note that each mixture has a different critical state line, which implies that the addition of fines particles creates different materials

Summary

Introduction

The effect of fines content is an important parameter to take into account when evaluating the mechanical behavior of silty sand since it is widely encountered in nature. Several alternative density variables were proposed in order to better capture the mechanical response of this kind of material like, for example, the intergranular void ratio [1] and the specific relative density [2]. In order to take into account either active and inactive fine particles, a new density variable was proposed: the equivalent intergranular void ratio which is calculated as follows: e (1 b) f e* c (1). The main purpose of this work is to verify the effectiveness of the equivalent intergranular void ratio concept in characterizing the mechanical behavior of natural silty sand

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