Geotechnical study in Flaçà

In Flaçà, the predominant substrate comprises sandstones, conglomerates and flysch, accounting for more than half of the ground, which favours an adequate bearing capacity for buildings, except in localised areas where expansive clays or fine sands may occur. This geological setting is characterised by low permeability at the surface, although aquifers can be found at greater depth. The compact gravels and sands, which occur occasionally, also provide good conditions for shallow or semi-deep foundations, unlike areas with soft clays, which require a detailed geotechnical study to avoid differential settlement.

Seismic activity in the municipality is very low, with only two events in thirty years and a maximum magnitude of 1.6, so seismicity does not affect structural design. In addition, the absence of karst removes risks associated with instability due to dissolution or collapses. Since the substrate is mostly not clayey, there are no relevant concerns regarding expansivity. Overall, the main point to consider is the accurate identification of the local lithology in order to select the appropriate support level, without additional restrictions of importance.