Updated skeleton void ratio for gravelly sand mixtures considering effect of grain-size distribution

Abstract

Recent researches on the behavior of gravelly sands advocate for the use of skeleton void ratio to characterize their density state. Skeleton void ratio corresponds to the void ratio of grains constituting the stress-bearing skeleton. However, such a void ratio relies on parameters difficult to determine in practice, such as the fraction of fine grains that take part actively in the load bearing skeleton. Also, it fails to consider the effect of Grain Size Distribution (GSD) of gravel and sand grains. Therefore, the skeleton void ratio index introduced by Chang et al (2015) is revisited to account for the effect of GSD of both gravel and sand grains. Two semi-empirical equations are developed in this paper to connect GSD parameters with skeleton void ratio parameters. The validity of the proposed equations has been checked for a particular class of gravelly sand materials. A series of specially-designed drained triaxial tests on gravelly sands were then conducted. Test results show that it is essential to consider the effect of GSD when using skeleton void ratio index. It also verifies the effectiveness and applicability of the proposed updated skeleton void ratio, which shows advantages in characterizing critical state lines of gravelly sands.

Discussion of “An updated skeleton void ratio for gravelly sand mixtures considering the effect of grain size distribution”

“…and fine materials Wang et al (2022) defined the particle diameter 4.75 mm (sieve number 4) as a separation limit between coarse and fine materials. They reasoned the limit "according to the Unified Soil Classification System (USCS classification, 2017), aggregates with grain size ranging from 4.75 mm to 20 mm were selected as gravel grains and grains with grain size below 4.75 mm and over 0.075 mm were selected as sand grains.".…”

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Wang et al (2022) have presented a good paper related to estimating the skeleton void ratio of grave-sand mixtures. The most important contribution is that Wang et al (2022) presented a new relationship to determine the skeleton void ratio and the parameters used in the relationship are easy to be obtained.

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Wang et al (2022) have presented a good paper related to estimating the skeleton void ratio of grave-sand mixtures. The most important contribution is that Wang et al (2022) presented a new relationship to determine the skeleton void ratio and the parameters used in the relationship are easy to be obtained. Their paper related the grain size distribution properties of the coarse and fine materials, namely, coefficient of uniformity of fine material and coarse material and the ratio of the diameter corresponding to 50% of the coarse materials and the fine materials.

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