Effect of Fines Content on Dynamic Properties of Sand Using Bender Element

Abstract

Shear wave propagation in the soil is a physical phenomenon and has been used widely for monitoring as well as for assessing the seismic property in geotechnical engineering. Shear wave velocity (Vs) and small-strain shear modulus (Gmax) are the key parameters in defining material response to various dynamic loadings. Generally, sand is weak in dynamic loading and also contains few non-plastic fines up to a certain extent. Thus, to have a better fundamental understanding of the deformation behaviour of sand fines mixtures, a bender element tests have been performed. From the bender element tests, it was concluded that Gmax is significantly dependent on relative density which is a function of void ratio, fines content and confining pressure. It was also observed that the value of shear wave velocity and shear modulus depends upon saturation. Dry specimen comparatively gives a higher values of shear wave velocity and shear modulus than a saturated specimen. It was also observed that up to certain fines content, the maximum and minimum void ratio decreased and after that, there was an increase in maximum and minimum void ratio. Based on regression analysis technique a modified model for evaluation method of small strain shear modulus (Gmax) of sand-fines mixture was proposed and verified using equation proposed by Seed and Idriss (1970). Test results indicated that the modified equation accounting for the influence of fines content can predict the Gmax of sand-fines mixture satisfactorily. From the experimental results, it was concluded that fines content plays an essential role in shear wave velocity and small strain shear modulus.