Potential and Consequences of Earthquake Induced Liquefaction Under a Gravity Based Structure

Abstract

This study focused on the potential liquefaction due to earthquake shaking of a gravity based structure (GBS) located off the northeast coast of Italy in the Adriatic Sea. The reinforced concrete GBS is 88 m wide by 180 m long and is underlain by a sand unit with variable thickness that could cause differential settlement and sliding. We first estimated settlements using cone penetration test (CPT) based liquefaction triggering methods and simplified settlement calculations with adjustments to account for the influence of the GBS. We then performed the same calculations but with the earthquake demand estimated from 1D site response analyses. Finally, we performed 2D finite element analyses of the soil-structure system using the advanced constitutive model PM4Sand to model the liquefiable sand layers. The results show that the total amount of displacement is small (1.5–7.5 cm), and no significant differential settlement or sliding is expected for the design earthquake scenarios. A practical observation from the study is that the more detailed and integrated analyses resulted in lower estimates of settlements and a more accurate representation of the soil-structure response.