The influence of intense fissuring on the compression behaviour of two Italian clays

The paper discusses part of the results of an on-going experimental research which is being carried out at the Technical University of Bari with the aim of assessing the influence of different levels of fissuring, intensity on clay mechanical behaviour. In particular, the intrinsic properties, the geological history, the natural structure and the compression behaviour resulting from an extensive experimental investigation carried out on both Senerchia and Santa Croce di Magliano clays outcropping in the Southern Apennines are presented. The clays possess an intensely fissured mesostructure (defined as scaly), as it is often the case for clays outcropping M the Southern Apennines. Such intense fissuring network is the result of the huge shearing strains experienced by the soils during their tectonic history. As first the paper discusses briefly the geological setting of the sampling sites. Thereafter, the clay mesostructure is characterised by means of a new classification chart for fissuring and the clay behaviour in both one-dimensional compression and swelling is discussed and compared with that of the same clays when reconstituted. The microstructural changes occurring during loading and unloading are also investigated by means of Scanning Electron Microscopy. The oedometer test results give evidence to a framework of compression behaviour for the intensely fissured clays being discussed.