Seismic Response of Reinforced Steep Soil Slopes: Results of a Shaking Table Study

A series of shaking table tests were performed at the University of Washington as part of a larger investigation of the seismic response of geosynthetic reinforced soil (GRS) slopes. The model slopes, 4 ft in height, were constructed with a wrapped faced at a slope of 63°. All were designed to have a static factor of safety of 1.0. The models were subjected to a sinusoidal frequency of 5 Hz on the shaking table. Model characteristics such as embedment length to slope height ratio (L/H) and geosynthetic spacing were varied in the testing program. Backfill settlement, significant lateral and vertical shearing in the reinforced zone, and development of a graben type failure wedge in the backfill behind the zone of reinforcement were observed. Test results indicated that as the L/H ratio and reinforcement strength increased and the reinforcement spacing decreased, the yield acceleration for the slope increased. A definite bi-linear failure surface was observed in all slopes. The results of the study indicate that GRS slopes are very safe in terms of their seismic resistance.