Modelling the behaviour of large gravity wharf structure under the effects of earthquake-induced liquefaction

Gravity Wharf Structures are widely used worldwide to form shallow and deep water ports. They are large structures with a height of 25-50 m depending on the water depth. When these structures are to be sited on loose to medium dense sand, earthquake induced liquefaction settlements present a significant risk. This often requires expensive soil replacement or other ground improvement techniques. In this paper, the dynamic behaviour of these large structures that exert very high bearing pressures on the foundation soil was investigated for the first time. The level of settlements they can suffer due to soil liquefaction was investigated using dynamic centrifuge testing. It will be shown that the full liquefaction does not occur below the structure even when the free field soil fully liquefies during strong earthquakes. However there will be some stiffness degradation owing to excess pore pressure generation and consequent structural settlements. The level of these settlements are considered to be acceptable from a Service Limit State (SLS) perspective. In addition to this the hydro-dynamic pressures that act on the Gravity Wharf structure were also investigated.