Abstract
Sand is a major component of soils. It is widely used in manufacturing and construction. In geomechanics, one characterizes sand according to various aims. This paper investigates, for local sands, the effect of grain size and granular distribution on the mechanical behavior in terms of strength and stress-strain relationship. For this purpose, dune sands of the great Occidental Erg, from Algeria, are analyzed, according to the Mohr-Coulomb criterion. The study uses three kinds of sands. Every kind is divided into three sizes classes. Then, the experimental program conducts a set of direct shear tests, under various vertical stresses, using the small shear box (60 × 60 mm). The results show that the particle size and distribution have a direct effect on the mechanical behavior of the dune sand. Then, the dominant size class governs the natural sand behavior. Moreover, the peak shear strength increases as particle size increases. This indicates that there is an increase in peak friction angle with the increase of particles size and the sands consider as a purely cohesionless material. In addition, the experimental analysis shows that density and confinement stress is not sufficient to interpret the mechanical behavior. Indeed, mineralogy and surface state can influence the shear strength. These conclusions lead to the relevance of the sand genesis and the importance of the local materials thematic. Doi: 10.28991/cej-2021-03091730 Full Text: PDF
Highlights
Arid and semi-arid areas cover thirty percent of the world’s land surface [1]
An advanced automated direct shear testing apparatus (SHEARMATIC EmS) is used for direct/residual shear testing. It is based on the conventional direct shear test apparatus used by Taylor [31] and, Skempton and Bishop [32], which includes an upper and a lower shear box (Figure 3), and the sample is sheared along the interface plane by pushing the lower half shear box, horizontally, while a constant normal load acts on the upper half shear box
The results show that the residual shear strength in all tests is not significantly affected by particle size
Summary
Arid and semi-arid areas cover thirty percent of the world’s land surface [1]. The second largest erg in northern Algeria, after the Great Oriental Erg, is the Great Occidental Erg known as the Western Sand Sea. Many studies have investigated the aeolian sands to several targets as, geotechnical characterization [4], operating in pavement and concrete [5, 6], and soil reinforcement with sands [7, 8] In this context, the direct shear test has served over the past 50 years in geotechnical engineering. The study of Kirkpatric [18], showed the opposite, the friction angle decreases with an increase in particle size of two cohesionless materials. This was confirmed by Marsal [19] and Zelasko [20]. This study sets up an experimental program to analyze the effect of particle size and granular distribution on sands' shear strength and behaviour. Our fundamental hypothesis in conducting the present research is to confirm that the interface parameters depend –among other effects- on the granular distribution and the particles sizes at the interface
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