Geotechnical study in Ponferrada

In Ponferrada, schists and slates predominate as the substrate; these exhibit competent and stable behaviour, supporting adequate bearing capacity for foundations. Secondary lithologies include sandstones, conglomerates and flysch, together with compact gravels and sands, which can help to improve the ground’s load-bearing capacity locally for light and medium structures. In general, the low permeability of these formations limits the presence of deep groundwater, although shallow aquifers may occur and should be taken into account when planning the foundations.

The municipality records moderate seismicity, with 23 events over the last 30 years and a maximum magnitude of 4.7, a threshold that requires consideration of the seismic effect in structural design and the specification of foundations. Although the substrate is not clayey in nature, ruling out expansivity risk, the possible presence of karst highlights the importance of undertaking a specific verification to avoid problems of subsidence or localised instability before carrying out foundation works. Therefore, the geotechnical assessment should focus on these conditions, with control of karst and seismicity being the main factors to consider in Ponferrada.