Context

A 4m-high Betoatlas earth retaining wall has been built at a new a large-scale hospital redevelopment site in Daventry.

Challenge

Additional challenges included high-level services to one elevation, a pinch-point to another, and the need to include a footbridge.

Two of the elements needed to be handled as part of an enabling package and this saw the services being underpinned to the longest elevation by a network of soil nailing fixed through a surface membrane to maintain integrity during the temporary works. The pinch point was constructed by contiguous piles that enabled a vertical wall to be formed.

Solution

The permanent solution saw the soil-nailed section faced with a 4m-high Betoatlas wall in red with the rear of the wall incorporating a structural backfill reinforced with Betonap geogrid. A bespoke treatment was provided to face the contiguous piles with a vertical facing of red Leromur units. These dry-fixed units were braced by Betonap geogrids laid across the blocks and then vertically to the piles where they were held in place and tensioned by steel plates fixed to the piles.

The Leromur was jointed to the Betoatlas by forming a return head wall; this in turn extended at high level to fill under the footbridge that was supported on columns encapsulated by the wall.

A second phase of the works saw a Betoatlas earth retaining wall as a car park surround. This called for an existing brick structure to be buttressed as part of the works.