Geological and geotechnical characterization of the test site of Quinta do Foja, located in the soft soil deposit of Baixo Mondego

Abstract

The soft soil deposit of Baixo Mondego has been the object of a large research project devoted to its geological and geotechnical characterization. This paper presents the main geological features of the deposit as well as its most significant physical, identification, consolidation and stress - strain - shear strength properties, measured in the test site of Quinta do Foja. The soils tested show several apparently inconsistent characteristics of behaviour, such as a great variability of the physical properties against a relatively uniform composition, a very high plasticity that disagrees with the quantity and type of clayey minerals found and a quite unusual combination of high compressibility and high intrinsic shear resistance. Being organic matter the major source of all the original features of the soils' behaviour, it can be regarded as their most significant constituent, even if their organic content is relatively low.