Liquefaction resistance of carbonate sands from cone penetration tests = Résistance à la liquéfaction des sables carbonatés issue d'essais de pénétration au cône

Liquefaction assessment is normally carried out using semi-empirical approaches based on the pioneering study of Seed and Idriss (1982). The methods relate a penetration resistance measured in situ (preferably from cone penetration tests, CPTs) to observed instances of liquefaction and non-liquefaction of sandy deposits. However, the applicability of a simplified approach is questionable for materials which fall outside the range of silica sands and slightly silty sands for which it has been developed and extensively verified against field data. For such cases a more rigorous method is needed. Carbonate sands are well known and documented to behave differently from silica sands: at the same relative density, penetration resistance is generally lower than in siliceous sands, while cyclic laboratory testing indicates higher cyclic resistance. These observations cannot rationally be combined into the commonly used simplified liquefaction procedures. An experimental approach, based on the measured mechanical properties of the carbonate sands, is essential. This paper provides an example of calibration of liquefaction resistance from CPTU for a fill made of dredged carbonate sand, based on centrifuge CPTUs and cyclic laboratory tests.