Seismic testing of model-scale geosynthetic-reinforced soil walls

SUMMARY This paper presents an experimental study on a series of reduced-scale model GRS walls with FullHeight-Rigid facings conducted on a shake-table at the University of Canterbury. Each model was 900 mm high, reinforced by five layers of stiff Microgrid reinforcement and constructed of dry dense Albany sand. The ratio of geogrid length L to wall height H, L/H, was varied from 0.6 to 0.9, while the wall inclination was generally vertical (90° to horizontal) with 70° for one test. During sinusoidal shaking, facing displacements and accelerations within the backfill were recorded. Failure for all models was predominantly by overturning, with some small sliding component generated in the final shaking step. An increase in L/H resulted in a decrease in wall displacement, while a decrease in wall inclination from the vertical resulted in similar benefits. Detailed analysis of the deformation of one of the tests is presented. During testing, global and local deformations within the backfill were investigated using two methods: the first utilised coloured horizontal and vertical sand markers placed within the backfill; the second utilised high-speed camera imaging for subsequent analysis using Geotechnical Particle Image Velocimetry (GeoPIV) software. GeoPIV enabled strains to be identified within the soil at far smaller strain levels than that rendered visible using the coloured sand markers. These complementary methods allowed the spatial and temporal progressive development of deformation within the reinforced and retained backfill to be examined.