Dynamic centrifuge testing of a cantilever retaining wall

Two correctly-scaled model cantilever retaining walls of different stiffnesses were tested under dynamic loading conditions in a centrifuge. A medium-dense fine sand was retained with a range of backfill slopes. For the centrifuge model, an earthquake-generating mechanism was designed to produce seismic shaking equivalent to that generated at ground surface in the epicentral area of an earthquake of approximate magnitude 5–5. The response of the model retaining walls to the input dynamic motion was measured by strain gauges, pressure transducers and accelerometers. From the measurements plots were constructed of moment, shear, pressure and displacement over the height of the walls as a function of time. The results are compared with calculations based on the quasi-static Mononobe-Okabe theory. Although the calculated resultant force is in reasonable agreement with the experiments, the moments can be substantially different. Residual values of all parameters at the end of shaking are considerably greater than the initial static values. It is recommended that dynamic behaviour be incorporated in the earthquake design of retaining walls