Bender-element (BE) tests were conducted on clay-sand mixtures to investigate the variation of small strain-shear modulus (G max) with the sand content and the physical characteristics (size, shape) of the sand grains in the mixtures. Three different gradations (0.6-0.3 mm, 1.0-0.6 mm and 2.0-1.0 mm) of sands having distinct shapes (rounded, angular) were added to a low-plasticity clay with mixture ratios of 0% (clean clay), 10%, 20%, 30%, 40%, and 50%. For the purposes of performing a correlation analysis, unconfined compression (UC) tests were also carried out on the same specimens. The tests indicated that both the G max and unconfined compressive strength (q u) values of the specimens with angular sand grains were measured to be lower than those with rounded sand grains, for all sizes and percentages. As the percentage of sand in the mixture increases, the G max values increase, while the q u values decrease. The results further suggested that the G max values decrease as the q u values decreases as the size of the sand grains reduces.
The aim of this study is to assess the influences of both the size and shape of sand grains mixed with a clay on shear modulus (Gmax)– and shear wave velocity (vs)–based liquefaction resistance (cyclic resistance ratio, CRR) using an intensive series of bender element (BE) tests. A low plasticity clay (CL) was added to two specific particle gradations (0.15–0.30 mm, and 1.0–2.0 mm) of clean sands with particular shapes (angular and rounded) at the percentages of 5, 10, 15, 20, 30, and 40, by dry weight. The BE tests were performed on the remolded specimens of different size/shape sands containing various amounts of CL in a recently designed mold used specifically for cohesionless soils, and then the values of vs, Gmax, and CRR were investigated. In most of the cases, the testing results indicated that, up to 20 % fines, which is named as transition fines content (FCt), Gmax and CRR values decreased, and then they increased for the specimens tested. Eventually, Gmax and CRR values of the specimens were significantly changed by the physical features (size, shape) of the sand grains with all the clay inclusions and frequencies applied.
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