Deformation of centrifuge models of clay embankments due to ‘bumpy road’ earthquakes

A model study of deformations of kaolin embankments during earthquakes has been carried out using a ‘Bumpy Road’ actuator to impose earthquake-like base accelerations on centrifuge models. This paper begins by briefly describing the earthquake simulating apparatus. The results of the model tests indicate that predictions of displacement using sliding block type calculations need to take account of softening of the soil during the earthquake. A simple mathematical model for degradation of strength with increasing block displacement is shown to satisfactorily account for softening. In one model test, strain softening and pore pressures caused by an earthquake apparently induced a collapse of the model a few seconds after the earthquake. Delayed failure produced deformations of an order of magnitude larger than any measured during actual base shaking.