Geotechnical study in Santander

In Santander, the dominant geological substrate is composed of limestones, dolomites and marbles—materials with high strength and excellent bearing capacity—which favours shallow foundations, especially strip footings and rafts. Although fine sands, silts and some areas of anthropogenic fill are recorded locally, their distribution is occasional and they tend to show lower competence, so they require a specific assessment if they are proposed as a founding stratum. The presence, albeit infrequent, of gypsum, anhydrite and salts adds a monitoring factor for possible dissolution processes, particularly in areas with groundwater flow.

Seismicity in Santander is considered notable, with 145 events in the last 30 years and a maximum magnitude of 4, which makes it necessary to consider seismic actions in structural design. In addition, the karstic nature of the limestones and dolomites requires special attention to rule out cavities or sinkholes before carrying out any foundation. Since the predominant substrate is not clayey, the risk of expansiveness is ruled out. In conclusion, checking for karst-related phenomena and paying attention to possible dissolution in gypsum are the main conditioning factors for the safety and feasibility of foundations in Santander.