Geotechnical study in Lobón

In Lobón, the subsoil is mainly composed of sandstones, conglomerates and flysch, representing almost half of its near-surface stratigraphy. Frequent deposits of compact gravels and sands also occur, which, in general, provide a good bearing capacity for conventional foundations. However, the local presence of fine sands and silts requires special attention in specific areas, as they may reduce bearing capacity. Limestone, dolomite and marble formations are present only rarely, and the presence of water masses is very low. In general, the lithological base is suitable for direct or semi-deep foundations, but it is recommended to verify the homogeneity of the substrate in situ during the geotechnical investigation campaign.

The seismicity recorded in Lobón, with 52 events over the last 30 years and a maximum magnitude of 4.4, is considered notable, and therefore constitutes a factor to be taken into account in the structural sizing of projects. There are localised areas with expansive clays, associated mainly with certain climatic sectors; this phenomenon poses a risk to shallow foundations due to possible swelling–shrinkage movements that can induce defects in structures. There are no constraints associated with karst, and the main geotechnical limiting factor is localised expansivity, which must be carefully assessed before foundation design.