Estudio geotécnico in Bridges

In Ponts, the geotechnical substrate is dominated by sandstones, conglomerates and flysch, which together constitute approximately 75% of the ground, whereas fine sands and silts occur in the remaining 25%. These formations are usually compact and provide good bearing capacity, although the presence of silts can induce some susceptibility to deformation if they are used as a support level for shallow foundations. Generally, the low permeability of these materials limits infiltration, but there may be near-surface aquifers associated with more permeable layers, which requires attention in foundation and drainage projects.

With regard to seismic behaviour, Ponts records very low activity, with only one event in 30 years and a very low maximum magnitude (Mmax 1.6), meaning that seismic actions are not a determining constraint. The non-clayey substrate rules out risks derived from expansiveness, which favours ground stability for direct supports. However, given the possibility of karst phenomena such as caves or dissolution, especially in areas of flysch or carbonate formations, it is essential to verify the presence of karstification before any foundation work, as this can compromise structural safety.