Precast piles are a robust and cost-effective alternative piling solution for civil engineering and infrastructure projects. Offering a number of benefits and advantages over existing methods, including cost, Aarsleff is proactively challenging the current mind-set and driving change throughout the construction sector.
An Engineering Overview
Whilst the UK Construction Industry defaults to Large Diameter Bored Piles for infrastructure work, In Europe and beyond, the use of Precast Concrete Driven Piles or Steel Tubes are the norm. Using a combination of vertical and raking piles a solution can be provided that efficiently caters for the vertical and longitudinal actions associated with bridge abutments, piers and many other structures.
The combination of actions can be resolved into axial loading, however, should there be any resulting lateral load or induced bending moment from embankment surcharge; Aarsleff's proprietary Engineering Piles can be reinforced to suit.
A worked engineering overview of a precast concrete pile alternative that offers a viable cost-effective and sustainable alternative is presented here.
Consider a single span road bridge with typical bridge end support loads of say 12,000kN in compression and 600kN longitudinal load. Current UK design approach currently favours a single row of large diameter bored piles in the region of 900mm to 1200mm nominal diameter. Consider 1050mm piles, 15m long piles with 10No. H40 full length main bar reinforcement.
- Concrete Volume = 65m3
- Weight of Steel = 7.4 tons
- 65+ m3 of spoil to remove
- On-site curing time to be allowed for
- Adjacent piles cannot be installed in the same day, increasing costs in sequencing arrangement and program time
- Weather dependent
- Approximate Piling Cost £40,000 to £45,000
The alternative option as adopted widely on the continent as show above for the same bridge abutment example. A combination of a single row of vertical piles with a corresponding row of raking piles as shown above can be used to effectively resist the axial and lateral loads applied by the bridge abutment.
- This offers a saving of 28m3 of concrete and 2.1 tons of steel
- Zero spoil to handle or remove from site
- Clean operation
- Off-site build = Zero curing time on site
- Factory Quality Piles
- Piles installed in sequence therefore releasing follow on trades earlier and matching or bettering on-site install program compared to opposite
- Installation not effected by cold weather and offers a reduction in traffic movements on site
- Approximate Piling Cost £25,000 to £30,000