Geotechnical study in Real Sitio de San Ildefonso

In the municipality of Real Sitio de San Ildefonso, a substrate of slate and schists predominates: metamorphic materials with high compactness and low deformability. This confers a notably high bearing capacity and a predictable behaviour as support for shallow direct foundations, particularly at the surface. The secondary presence of granite and gneiss, together with compact gravels and sands, reinforces the overall suitability of the ground. Meanwhile, the scarce occurrence of clays and hard marls does not constitute a relevant constraint in selecting the type of foundation; however, it is recommended to confirm the homogeneity of the strata by means of specific boreholes. In addition, permeability is low, which prevents reductions in bearing capacity due to the presence of water, although it is recommended to assess the possible existence of shallow aquifers in phases prior to the project.

The seismicity in the area is at a high level, with a record of more than 200 events in the last 30 years and a maximum magnitude (Mmax) reaching 4.7; therefore, it is a factor to be considered in structural design and in the selection of the seismic parameters in accordance with the current regulations. The non-clayey substrate rules out risks related to expansivity, enabling a more efficient and safer design of the structures. In summary, the main technical constraint for geotechnical studies in Real Sitio de San Ildefonso is seismicity, which requires priority attention to ensure the stability and safety of the planned buildings.