Soil liquefaction resistance of foundations for proposed Breakwater Road Bridge at Geelong, Victoria

This paper presents a case history of a preliminary liquefaction assessment for bridge pile foundations for the Breakwater Road Realignment Bridge in Geelong, Victoria. The bridge site is situated on an alluvial plain of the Barwon River delta and is underlain by a layer of very loose sand sediments. Concerns were raised regarding the potential liquefaction of the very loose sand sediments and the potential impact that soil liquefaction may have on the proposed pile foundations of the bridge. A soil liquefaction assessment was carried out using the procedures initially developed in the 1970s and 1980s (Seed and Idress 1971 and 1982) and lately revised by Youd and Idress et al. in 2001. While the majority of the piled foundations at the site were assessed not to be at risk of liquefaction, two pier locations where very loose sand was encountered were assessed to be potentially liquefiable under the design earthquake loading. At these locations, the pile groups were designed under earthquake loading to allow for the potential liquefaction of the loose layers.