ABSTRACT
If the soil element is unloaded, as it is the case with natural processes, such an erosion of overlying sediments, or with a man-made process, such an excavation, it increases in volume along the swelling line but at a much slower rate. In particular, the process of building and dismantling the previous cathedral induced on the supporting soil a loading and unloading process in the western zone so that part of the Lanfranco Cathedral was built on less compressible soils. The reduction of the water pressure with respect to its initial value will cause an equivalent increase of effective stresses, which will give rise to a compression of the underdrained soil and subsidence of its surface. The soil has memory of its previous loading history, as it is revealed from the fact that, when the specimen is further reloaded starting from D, its behavior appears to be reversible until the current yield stress has been attained.
