Estudio geotécnico in Andoain

In Andoain, the dominant bedrock is composed mainly of shales and schists, covering around 72% of the municipality, followed in smaller proportions by sandstones, conglomerates and flysch. These materials are generally impermeable or have low permeability, which restricts the capacity to host water at depth, although the presence of shallow aquifers is possible in isolated areas. The bearing capacity is usually adequate for these types of metamorphic rock, allowing the execution of shallow foundations provided that the homogeneity of the bedrock at depth and its structural integrity are verified.

The municipality is characterised by very low seismicity, with only 3 recorded events in the last 30 years and a maximum magnitude of 2.3—parameters that do not condition the structural design. However, it is important to highlight the potential presence of karstic phenomena due to the karst detected in the subsoil, which requires thorough verification to rule out the existence of cavities or dissolutions before undertaking any foundation works. The non-clayey bedrock eliminates the risk of expansivity, so the main constraint lies in the need to assess stability against karst processes, ensuring the safety of the planned structures.