Strength of various sands in triaxial and cyclic direct shear tests

This paper presents the result of an extensive series of experimental investigation carried out in triaxial and cyclic direct shear tests on sands having various properties, which were obtained from different locations in Turkey and in Northern Cyprus. In order to investigate the link between strength and physical properties (i.e., shape) of the sand particles, three series of triaxial tests (Consolidated-Drained, CD; Consolidated-Undrained, CU; and Unconsolidated-Undrained, UU) for each were performed under three different confining pressure values (450 kPa, 500 kPa, and 550 kPa) with a back pressure of 400 kPa. The cyclic shear behaviour of the sands was tested by considering the normal stresses of 50 kPa, 100 kPa, and 150 kPa. Experimental results in both triaxial and cyclic direct shear tests showed a relation between the physical properties of the sands and the behaviour of them under monotonic and cyclic loading. The given pictures show the physical differences/similarities among the sands used during the investigation. The goal of the presented experimental investigation is to have an understanding of the behaviour due to shape characteristics (i.e., roundness, sphericity) of these four types of sands (Narli, Birecik, Trakya, and Crushed Stone), which are widely used in earthwork projects in certain parts of Turkey and Northern Cyprus.

► NS, BS, TS exhibit dilation, the CSS exhibit contraction.
► CSS exhibits a higher strength than the other three sands.
► The higher R and S values cause to a higher strength and lower volumetric strain.
► NS, BS, and TS have relatively rounded shapes, CSS has more angular shape.