Geotechnical study in Garrucha

In Garrucha, the characteristic soils are fine sands and silts, making up more than 80% of the surface substrate, occasionally accompanied by formations of limestones, dolomites and marbles. This composition implies predominantly fine-grained soil types, which may affect a moderate bearing capacity, particularly in areas where silt-sand fractions predominate. For shallow foundations, it is essential to analyse the compaction and homogeneity of these layers, resorting to deeper solutions only when the geotechnical values require it. Compacted gravels and sands, although in the minority, can improve the ground’s mechanical behaviour locally.

Seismic activity in Garrucha is very low, with only 3 events in the last 30 years and a maximum magnitude of 1.7, so this factor does not represent a significant requirement in structural design. There are also no signs of karstification in the area, and the absence of clayey substrates rules out the presence of expansive soils, thereby eliminating problems of swelling or shrinkage. Therefore, the main geotechnical constraint is to ensure adequate characterisation of the bearing capacity and consolidation of the silt-sand soils, especially in areas close to local water bodies or in zones that may be prone to saturation.