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Calcareous siltsare encountered in many offshore areas where oil and gas exploitationsaretak-ing place (e.g., Arabian gulf, southeastof Brazil, south east and north west of Australia). Understanding be-haviorof calcareous silts remainschallenging as undisturbed siltsamples are difficult to obtain, and most studies rely on remouldedsiltsamples. The purpose of this paperis to characterizethe mechanical behaviorof intact and remouldedoffshore calcareous silts from two different water depths. The comparisons are done based on microstructure characterizationusing scanning electron microscopy (SEM) images supported by in-dex tests, one-dimensional compression tests and undrained monotonic triaxial tests. The results have shown that,except for the critical state friction angle, the behaviour of remoulded silts differs from that of intact silts, due to the change in microstructure, which appears to be more compact with less intact open shellparticles.

This paper presents the results of an experimental program aimed at characterizing tube specimens from an estuarine soft clay deposit, which contains variable amounts of shells. The characterization of the natural clay involved two non-destructive techniques for assessing specimen quality, namely computed axial tomography (CAT) and shear wave propagation using bender elements, as well as one-dimensional consolidation tests for evaluating soil compressibility. Image analysis of CT scans was used to quantify the volumetric shell fraction and its influence on the compressibility parameters derived from one-dimensional compression tests. The experimental results show that both the compressibility and the small-strain stiffness of the natural soft clay are influenced by the volumetric shell fraction.