Geotechnical study in Madrid

In Madrid, the subsurface is predominantly composed of sandstones, conglomerates and flysch; materials that generally exhibit good bearing capacity and favourable mechanical behaviour for the execution of shallow or semi-deep foundations. The significant presence of granite, gneiss and other igneous rocks supports the geotechnical stability of the ground and allows direct foundations when these compact levels are reached. Carbonate formations such as limestones, dolomites and marbles, although less frequent, may also be found, and it is important to assess locally the possibility of abrupt changes in strength.

As regards seismicity, Madrid shows very low seismic activity, reflected in only 5 events over 30 years with a maximum magnitude of 3, which implies low requirements in structural design against seismic loads. Although the substrate is not clayey and the risk of expansivity is ruled out, the possible development of karst processes in the carbonate strata requires thorough verification before establishing the most suitable foundation type; the potential presence of karst is the main geotechnical conditioning factor to be analysed in the area.