In urban areas, the impermeable foundations of buildings and underground tunnels are often submerged in the groundwater. In particularly unfavorable geological settings ,the water flow is modified by these obstructions which can produce faults as well as cracks and tears in foundations. Sometimes, the buildings can collapse because of submerged foundations.In order to describe and classify the most probable geological settings which may cause these problems, some typical cases of Italian floodplains conditions have been examined in this paper.
As it is well known, the alluvial plains area are characterized by sediments with a variable permeability and lenticular texture, slightly dipping downwards. The frequency of lenses of different dimensions and thickness, the occurrence of buried riverbeds and the presence of aquicludes, can produce heavy changes both in pressure and in flow directions locally, influencing the distribution of preferential groundwater flow and its direction. This paper deals with the consequences on foundations stability arising from the most common geological settings in order to suggest a suitable monitoring approach useful to avoid buildings damages.