Geotechnical study in Fraga

In Fraga, the dominant geological substrate is formed by limestones, dolomites and marbles: competent materials with good mechanical properties, which is reflected in a high bearing capacity that is favourable for shallow foundations. Locally, gypsum, anhydrite and salts are also present, together with areas of fine sands, silts, sandstones and smaller fluvial deposits. Areas of deltaic muds and peats, although very rare, should be avoided as bearing levels due to their low strength and high deformability. The overall permeability is low, although shallow aquifers may occur in certain areas.

The seismicity of Fraga is very low, with few recorded events and a low maximum magnitude, so it does not represent a relevant constraint for the usual structural design. The substrate does not contain expansive clays, ruling out the risk of expansivity. However, the presence of gypsum and salts implies a potential risk of dissolution, which must be assessed specifically for the site area of each project. The main geotechnical consideration when carrying out a geotechnical study in Fraga is to verify the presence of potentially soluble soils and the point-wise occurrence of organic materials that are unsuitable for foundation.