Confining Stress Effects on the Stress-Strain Response of EPS Geofoam in Cyclic Triaxial Tests

This paper summarizes the results of a laboratory study addressing the cyclic stress-strain response of expanded polystyrene (EPS) geofoam under various confining stresses. Experimental results from cyclic uniaxial and triaxial compression tests conducted in the viscoelastic domain revealed that the normalized shear modulus degradation curve is insensitive to the static confining stress, whereas the damping ratio of EPS geofoam appears to increase with increasing static confining stress. The visco-elasto-plastic response of EPS geofoam also seems to be affected by the magnitude of the applied static confining stress in cyclic triaxial tests. An increase in the static confining stress is associated with a reduction in the accumulated permanent (plastic) strain for a specific number of applied loading cycles.