In situ and laboratory experiments have shown that electrical resistivity tomography (ERT) is an effective tool to image transient phenomena in soils. However, its application in quantifying soil hydraulic parameters has been limited. In this study, experiments of water inflow in unsaturated soil samples were conducted in an oedometer equipped to perform three-dimensional electrical measurements. Reconstructions of the electrical conductivity at different times confirmed the usefulness of ERT for monitoring the evolution of water content. The tomographic reconstructions were subsequently used in conjunction with a finite-element simulation to infer the water retention curve and the unsaturated hydraulic conductivity. The parameters estimated with ERT agree satisfactorily with those determined using established techniques, hence the proposed approach shows good potential for relatively fast characterisations. Similar experiments could be carried out on site to study the hydraulic behaviour of the entire soil deposit.

The characterisation of unsaturated intermediate and coarse-grained soils faces some practical difficulties because undisturbed sampling is not easy. Geophysical methods provide useful information as they can be applied on site for testing geo-materials in their natural state. Moreover their repeated application over time is effective and efficient for monitoring purposes. A procedure for evaluating porosity and degree of saturation on the basis of electrical resistivity and wave velocities measurements is proposed. The approach is based on an electro-seismic model that utilises Archie's law to describe the electrical behaviour of soils and a recent formulation of elastic wave propagation in unsaturated soils. The proposed procedure is applied to laboratory data, and shows promising results.

Historical masonry towers survive at an alarming angle of inclination and may be in danger of leaning instability due to the lack of stiffness of the supporting soil. Therefore, careful investigation is required to estimate the seismic vulnerability as well as its long-term behavior. These problems require a multidisciplinary approach to properly model the behavior of the structure and its interaction with the supporting soil. This article is intended to contribute to these aspects, by showing how identification analyses can highlight the role of soil–structure interaction, and focuses on the model-updating techniques to forecast its behavior under seismic events.