ABSTRACT
The effect of preshaking on the liquefaction behaviour of sandy soils is studied in this paper. The research incorporated data from centrifuge and full-scale experiments. State of the art tools and sensors were used in the tests in order to capture as precisely as possible the response of the soil and connect it to the field. The tests simulated the effect of several decades of earthquake events on a 5-6 m uniform clean sand horizontal deposit, including both events that liquefied the deposit and others that did not liquefy it. The centrifuge model subjected to shaking events of types A, B, C and D, while the full-scale model to types A, B and C. An Event A represents a mild to moderate earthquake shaking; an Event B represents a mildly strong earthquake shaking; and Events C and D represent strong to very strong extensive liquefaction shaking in the field. The results of the experiments showed that the combination of mild/moderate (Events A) to mildly strong (Events B) shakings resulted in a significant increase in liquefaction resistance of the deposits over time. However, the occurrence of extensive liquefaction, caused by an Event C or D, resulted in a dramatic immediate reduction in liquefaction resistance.
