Geotechnical study in Oliva de Mérida

In Oliva de Mérida, the ground is formed mainly by phyllites and schists—metamorphic materials that exhibit high density and low deformability—features that favour a good bearing capacity for shallow foundations. As a secondary component, soils of sandstones and conglomerates contribute some variability and may provide intermediate strengths, whereas overconsolidated clays and layers of sands and silts, although present only occasionally, may require a specific assessment due to their behaviour with water and their density. In general, the low permeability of these soils limits the presence of water that could affect the foundation, although the existence of shallow aquifers at certain points should be assessed during the geotechnical study campaign.

Seismic activity in Oliva de Mérida can be considered significant, with 52 events over the last 30 years and a maximum magnitude of 4.4. While this level of seismicity does not reach the threshold that, under regulations, requires advanced structural design, it does suggest that the seismic parameters should be reviewed in the geotechnical analysis. The fact that the dominant bedrock is not clayey rules out the risk of expansivity, simplifying the expected behaviour of the ground with respect to moisture. Consequently, the main precaution in the area lies in correctly characterising the heterogeneity of the bedrock and considering the possible impact of aquifers, before defining the type and depth of the foundation.