Construction methods · Driven piles

Impact hammers: hydraulic, diesel and drop

The hammer decides whether a pile reaches depth and arrives undamaged. Hydraulic hammers give controllable energy and are the modern default; diesel hammers are simple and powerful but smoky and less controllable; drop hammers survive on small jobs and for driven cast-in-situ piles.

How bridges get built · Driven piles · Impact hammers: hydraulic, diesel and drop

Also called: hydraulic hammer, diesel hammer, drop hammer, piling hammer selection

How it is done

Size the hammer with a wave equation analysis (GRLWEAP): enough energy to reach the required set without exceeding allowable driving stresses.
Match cushions and helmets to the pile type; concrete piles need a soft cushion, steel piles a hard one.
Record blow counts per 250 mm and hammer energy; stop at refusal criteria to avoid damage.

Where it fits

Every driven pile; hydraulic for concrete and pipe piles, diesel for steel where emissions are tolerated, vibro for sheet piles and easy soils.

Where it does not

Undersized hammers that cannot mobilise the toe; oversized hammers that break the pile.

Plant, pace and money

PlantHammer 5-40 t ram for bridge piles, leads or free-hanging, power pack.

ProductivityHammer choice can halve or double driving time.

CostHire USD 15,000-60,000 per month for large hydraulic hammers.

Risks and controls

What goes wrong

Overstressing the pile, hammer bounce and cushion failure, noise above 100 dB at 10 m without shrouds.

Quality assurance

Wave equation report before driving, energy monitoring, cushion replacement schedule.

Examples

IHC and Junttan hydraulic hammers dominate Asian and Middle Eastern bridge piling.