Paalutus

Paalutus is a construction technique used to create deep foundations by installing piles that transfer structural loads to deeper, more stable soil layers or bedrock. It is employed for buildings, bridges, offshore structures and other cases where surface soils cannot safely support the imposed loads.

There are several methods. Driven piles, made of precast concrete, steel or timber, are driven into the ground with a hammer or vibro-hammer and are common where there is a suitable soil layer near the surface. Drilled piles, or cast-in-situ piles, involve drilling a hole and filling it with concrete (often with reinforcement), used when driving would cause excessive vibrations or when soils are loose or soft. Large-diameter piles or caissons may be used in water or very soft soils.

Piles transfer load through end-bearing contact with a stronger layer or through skin friction along the shaft. End-bearing piles rely on a bearing surface at depth, while friction piles gain most of their capacity from shaft friction along their length.

The process includes site investigation, design, installation and connection to a pile cap or superstructure, followed by verification and testing. Tests can include pile integrity testing, dynamic tests or static load tests to confirm capacity and behavior under load.

Materials vary and include concrete, steel, and timber, with combinations or composites used in special conditions. Design must consider soil stratification, groundwater, scour, frost, corrosion protection, and environmental and noise or vibration impacts.

Paalutus is governed by national and regional standards and commonly aligned with geotechnical design codes such as Eurocodes in the European Union, along with project-specific quality assurance and testing requirements.