Geotechnical study in Bigues i Riells del Fai

In Bigues i Riells del Fai, the predominant subsoil is composed of sandstones, conglomerates, flysch and, in smaller proportions, granites, gneisses and other igneous rocks. These materials usually provide a high bearing capacity and stability for shallow foundations, whereas the occasional presence of fine sands and silts could require careful positioning of the strip footings. Particular attention should be paid to soils containing gypsum, anhydrite or salts, present in smaller proportions, due to the associated risk of dissolution and possible subsidence, as well as the use of muds or peats, which must be avoided as a founding layer beneath any structure.

Seismicity in the municipality is very low, with only 5 low-magnitude events recorded over 30 years, which limits the seismic influence on structural projects. However, the possibility of karstification linked to occasional limestones is noteworthy, and this must always be investigated through a geotechnical study before defining the foundation, given the potential existence of underground cavities or dissolution. Since the subsoil is not clayey, the risk of expansivity is ruled out, so the most critical parameter for design will be verifying karst-related processes in limestone areas and the presence of gypsum or salts.