Effect of Geofoam Inclusion on Dynamic Response of Mechanically Stabilized Earth Walls with Sand–Crumb Rubber Backfill

This paper investigates the effect of the inclusion of geofoam layers at the interface of wall and backfill on the dynamic response of mechanically stabilized earth (MSE) walls. In this aspect, 1-g model shaking table tests were conducted with sand–crumb rubber mixtures as backfill. The model wall of height 600 mm was used in the study. Tests were conducted by applying stepwise increasing peak ground acceleration (PGA) values varying from 0.063 to 0.59 g. The effect of different thicknesses of geofoam layers varying from 0.08 to 0.16H (H is the height of the wall) was investigated. The results revealed that the acceleration amplification in the backfill was reduced in the presence of sand–crumb rubber backfill compared to the sand backfill. The rubber–sand backfill showed a 38% increase in shear modulus and a 24.3% increase in damping ratio compared to sand backfill. The presence of deformable geofoam significantly reduced the lateral wall displacement and dynamic pressure on the wall. The wall displacement was found to be maximum at the top of the wall and reduced by 38% in the presence of the geofoam of 0.16H thickness. The pressure reduction determined in terms of pressure reduction efficiency (η_p) was found to be 61.3%. Further, the effect of the additional surcharge of magnitudes 5 and 10 kPa on the wall pressure was investigated. The pressure generated due to the surcharge loading on the wall was found to reduce with the increase in the geofoam thickness. Hence, it was concluded that installing geofoam layers marked a significant reduction in wall pressure with and without surcharge.