Geotechnical study in Siles

In the municipality of Siles, gypsum, anhydrite and salts predominate, as well as limestones, dolomites and marbles, followed in smaller proportions by slates, schists and detrital deposits. The gypsum- and evaporite-bearing materials imply a risk factor due to their potential ease of dissolution, which can give rise to instabilities and subsidence if they are used as support for foundations. On the other hand, the carbonate formations may show variability in their strength, but generally they provide good bearing capacity provided there are no karst cavities or significant alterations. The non-clayey substrate rules out relevant problems of expansivity in the foundation area.

The seismic behaviour in Siles is considered moderate, with 13 recorded events over 30 years, although the maximum observed magnitude of 2 indicates a low potential impact on structures. However, the presence of karst in the ground makes it mandatory to carry out a specific verification before undertaking foundations, in order to identify possible cavities or subsidence associated with the dissolution of gypsum and salts. The main geotechnical condition to address is the variability associated with evaporite materials and the potential existence of karstification—critical factors for the safety of foundations.