Monitoring of the Liquefaction of Nazaré's North Breakwater Foundations

Abstract

The northern breakwater of Nazaré's harbor underwent reconstruction after it suffered heavy damage during ocean storms. The initial thought for this deterioration was that of the impact of the waves. After some observation this idea was re-evaluated and it was suggested that the rupture mechanism was due to wave-induced liquefaction, this meaning a gradual build-up of pore-water pressure due to wave cycles, where for this to occur it needs a soil where the dissipation of this pressure does not match the rate of increase of the same pressure, causing both the water and the sediment to act together as a liquid. To verify if this phenomenon is in fact the cause of rupture, the instrumentation and geotechnical monitoring of waves, of the total and pore-water pressures in the foundation layer of the breakwater, and inside the breakwater itself were idealized.