Construction methods · Driven piles

Rotary screw (helical) piles

A steel pipe with a helical tip is screwed into the ground by a rotary head, with no spoil and little noise. In Japan it is a full displacement pile for medium loads; elsewhere helical anchors carry lighter structures and temporary works.

How bridges get built · Driven piles · Rotary screw (helical) piles

Also called: helical pile, screw-in steel pipe pile, rotary penetration pile

How it is done

Rotate the pile with a high-torque head on a crawler rig, adding sections by welding or bolted couplings.
Torque correlates with capacity; drive to the target torque in the bearing layer.
Connect to the cap with a welded plate.

Where it fits

Urban sites with noise limits, quick foundations for temporary works and small bridges, retrofit under existing structures with limited headroom.

Where it does not

Gravels and cobbles that stop the helix; large loads.

Plant, pace and money

PlantRotary rig with torque monitoring.

Productivity5-15 piles per shift.

CostUSD 150-300 per metre for 600-800 mm.

Risks and controls

What goes wrong

Helix damage, torque-capacity correlation drifting with soil type.

Quality assurance

Torque logs per pile, load tests on a sample.

Examples

Japanese highway viaducts near housing; falsework foundations.