Għadira sands as compared to normally consolidated deposits at Marsa (Ta’ Ċeppuna) : using static triaxial tests

Abstract

The results from an experimental study on Għadira clean sands and Marsa alluvial deposits are being presented. A series of nine undrained triaxial compression tests were performed on these soils, at three different confining pressures, ranging from 55 to 1200kPa for clean sands, and 200 to 800kPa for the alluvial deposits. The behaviour of clean sands was observed to follow the Critical state Framework, for which such sands tend to behave like over consolidated clays. On the contrary, the response of alluvial deposits is similar to that of normally consolidated clays. For the alluvial deposits, it was generally observed that as the confining pressures were increased, dilatant tendencies were observed to increase as well. However, the opposite was observed for clean sands, having high dilatant envelopes at low confining pressures, which is the general behaviour observed for normal soil. A difference in behaviour was also observed between the two alluvial deposits, as one was predominantly sandy in nature, and the other soil more silty in nature, both with a fraction of clay present within their soil structure. An attempt at determining the in-situ stresses of a silty clay from Marsa was also carried out.