A628 Tintwistle | King Post Piled Retaining Wall | Keller UK

A628 Tintwistle - King Post piled retaining wall

A Victorian retaining wall holding up a section of the A628 in Tintwistle, Derbyshire, was found to be showing signs of structural damage.

Keller, working for Interserve Construction, provided a king post piled solution to enable the construction of a new retaining structure, with minimal disruption on this key Trans-Pennine route.

Overhead telecoms cables could not be diverted, and vibration had to be minimal so as not to disturb the existing wall. These factors, coupled with difficult ground conditions, ensured that this was an extremely challenging project for its size.

Keller were able to provide a king post solution, where UKC steel sections were plunged in 4m lengths into a specially designed concrete mix. They were spliced end to end using either a welded connection or a plate and bolted connection, then lowered to the bottom of the pile.

A Klemm 709-2 sectional flight auger rig was used, to ensure that the piles could be constructed in the limited space and headroom.

A further challenge was the close proximity of ecology ponds in a nearby nature reserve, combined with a high groundwater table locally. To mitigate against the risk of contamination, Keller were able to offer a permanently lined solution to ensure that the ponds could not be polluted upon concreting.

As piles were installed, the main contractor monitored the pH levels of the nearby watercourses, and found no change. The solution provided had successfully mitigated any potential environmental issues.

Systems:  7 No. 660/600 diameter permanently lined Piles bored with sectional augers to 11m depth.

                  2 No. 660/600 diameter temporary works piles bored with sectional augers to 8m depth

Main Contractor: Interserve Construction

Year of Execution: 2016

Ground Conditions: 0-7.5m - Superficial clay and silt with some hard interbeds; 7.5m - Weak, highly weathered Interbedded sandstone and mudstone



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