Geotechnical study in Nigrán

In the municipality of Nigrán, the predominant substrate is mainly made up of sandstones, conglomerates and flysch, accompanied to a lesser extent by shales and schists. This lithological assemblage generally provides a good bearing capacity, although the local presence of fine sands and silts could give rise to less competent zones that it is advisable to characterise in detail. In terms of foundation design, the rocky nature of the ground and the low presence of cohesive soils make it possible to apply shallow or semi-deep solutions, adapted to the point-by-point assessment of the ground’s strength.

Seismicity in Nigrán is very low, with a record of only one event in 30 years and a maximum magnitude of 1.8, which minimises this factor as a conditioning requirement in structural design. The non-clayey substrate rules out the risk of expansivity, allowing greater stability against volumetric changes in the ground. In short, the main aspect to consider for the geotechnical study is the local characterisation of the substrate’s competence and the identification of possible levels of fine granular or silty-sandy materials, which could affect support conditions.