Shaking table study on sand-EPS beads-mixtures using a laminar box

Mixture of sand-expanded polystyrene (EPS) beads is one of the new geo-materials with high compressibility that can be used as a seismic buffer and base isolation due to its great capability for energy dissipation. In this study, a series of 1-g shaking table tests is conducted to assess the dynamic properties of the sand-EPS beads mixtures with a particular focus on the stress-strain response and the variation of shear modulus and damping ratio at the range of medium to large levels of strain. The influence of various parameters, including the amplitude of input base acceleration and EPS content, on the response of sand-EPS beads mixtures is examined. The physical model of sand-EPS bead mixtures showed a lower induced peak acceleration compared to the clean sand model. Moreover, the addition of EPS beads to sand reduced the deformations caused by dynamic loading. The results also revealed that the damping ratio and shear modulus of the samples depend on the EPS bead content, such that its increase results in the damping ratio increasing to 100% or more. On the contrary, the shear modulus of all sand-EPS bead mixtures undergoes a significant reduction with the increase in EPS bead content.