Estudio geotécnico in Donostia/San Sebastián

In Donostia/San Sebastián, the predominant geological substratum is formed by slate and schist, followed by limestones, dolomites and marbles that appear frequently. These lithologies generally provide good bearing capacity for shallow foundations, particularly in the presence of compact rock. The lesser presence of sandstones, conglomerates and fine soils such as sands and silts implies possible local variations in bearing capacity, although it is considered that the predominant ground behaviour is favourable for construction, requiring detailed studies of the depth and quality of the bedrock in each plot.

Seismicity in the municipality is moderate, with 10 events recorded over the last 30 years and a low maximum magnitude (Mmax 2.6), so it has hardly any impact on structural design. The substratum does not include expansive clays, ruling out the risk of differential movements due to expansivity. In addition, the absence of karstic phenomena minimises the possibility of subsidence through the dissolution of soluble materials. The main factor that conditions building in Donostia/San Sebastián is the precise identification and characterisation of the dominant lithology at the specific site, especially in transitions between different types of rock and softer materials.