On the effect of suction on the stability of ancient retaining walls

The paper briefly presents some results of a parametric study on the stability of old masonry walls retaining unsaturated backfill subjected to infiltration of water from the limit surface. The topic is discussed in order to show the importance of the role of suc-tion on the stability of such type of structures interacting with this kind of soils. It emerged that it is possible to guarantee the safety without very invasive interventions, like anchors, micropiles, shotcrete and so on, but only trying to avoid the saturation of the backfill with superficial or soil drainage. This approach is in agreement with the basic principles of restoration and their extension to the Ground-Monument System as defined by many documents produced by the Technical Committee TC-301 – Preservation of Historic Sites of ISSMGE