Influence of Fines Content and Type on the Small-2 strain Shear Modulus of Sand

Small-strain shear modulus, G0, is an important fundamental soil property. Although many studies have been conducted on this property for clean sands and pure clays,small-strain behavior for mixtures of sand and fines has been less addressed. Thispaper presents the results of a comprehensive laboratory study on G0 value of sandcontaining various amounts of different fines. To this aim, bender elements wereintegrated into a conventional triaxial apparatus, and shear wave velocity wasmeasured on samples of sand with different amounts of highly-plastic, medium- plastic, low-plastic, or non-plastic fines at different void ratios. Measuring the shearwave velocity and thus obtaining G0 at different void ratios and effective stresses, theintrinsic parameters that characterize G0 were determined for the tested materials.This allowed the effects of fines type and content on the G0 value of sand to beevaluated in a systematic manner. The G0 values of different sand-fines mixtureswere compared based on different density parameters. Results show that G0 of siltyand clayey sands is affected by both fines content and fines type. Therefore, in orderto estimate G0 of sand-fines mixture, not only the fines content but also theirplasticity needs to be properly accounted.