piling

Piling is a foundation technique that uses slender, long members driven into or formed within the ground to transfer loads from structures to deeper, more stable soils or rock. It is used when surface soils are weak, when high settlements are expected, or when structures must resist vertical and lateral loads. Piles reach below unsuitable layers and often work in groups connected by a pile cap.

Common pile types include end-bearing piles, which transfer most load through the tip, and friction piles, which rely on skin friction along the embedded length. Composite piles combine both mechanisms. Materials include timber, concrete (plain or reinforced), and steel. Piles may be driven into the ground, drilled and cast in place, or formed by continuous flight auger or screw/helix systems depending on soil conditions and access.

Load transfer depends on the soil and pile type. End-bearing piles gain capacity from a hard layer beneath, while friction piles gain capacity from skin friction along their surface. In practice, piles are installed in groups and connected to a structural cap; group effects and lateral loads influence design.

Design relies on geotechnical data and field tests. Static load tests or dynamic tests verify capacity. Capacity estimates use soil tests and correlations, refined by p-y or other lateral-load models. Designers consider groundwater, corrosion, frost, and scour, as well as construction limits such as noise and vibrations.

Applications include foundations for buildings, bridges, marine structures, and retaining walls. Piling enables support where shallow foundations are impractical or risky, and is adaptable to site-specific soil conditions and project budgets.