Groundforce Shorco has supplied its Rolling Strut Boxes to provide temporary support for a large linear excavation in preparation for the installation of a concrete culvert at an industrial site in Sheffield.
The Project
The civil engineering contractor was required to install a major pre-cast concrete culvert at a industrial plant, they then approached Groundforce Shorco for initial advice and subsequent preliminary temporary works design and costings.
The Challenge
Initial thoughts focused on a support solution comprising lines of sheet-piled and framed cofferdams. However, the depth and linear nature of the excavation lent itself to a Trench Box solution, which is quicker to install than sheet piles and frames.
However, two potential problems stood in the way of the box solution: the under-strut clearance needed for installation of the pre-cast culvert sections; and the width of the excavation (8.3m – 9.5m), which was outside the stated limit for the Groundforce Rolling Strut Box (6.6m).
The Solution
Despite the width of the excavation, analysis of the prevailing ground conditions and a review of the technical specifications of the Rolling Strut Box confirmed that the existing strut extensions and roller assemblies were capable of performing safely and efficiently without any bespoke modifications. The struts could be extended to suit the application.
Regarding the strut level, Groundforce technical department advised that, following the pouring of a 223mm base slab, the rolling struts could be lifted to make room for the culvert sections to be installed underneath.
Groundforce supplied 13 of its Rolling Strut Boxes in late June 2025.
Due to the widths required, the normal method of assembly was not suitable for this application. Instead, in an isolated area of the site. The contractor formed two slit trenches in concrete in which the boxes could be pre-assembled.
At a depth of 2m, these were formed at exactly the correct widths to allow the panels to be stood up in the trenches while the struts could then be assembled at ground level and lifted into position between the panels from above.
The contractor had provided a crawler crane to lift the culvert sections (which were double units weighing between 26t and 32t each) and this crane had sufficient capacity to lift the complete assembled Rolling Strut Box into position within the excavation.
The Rolling Strut Boxes are designed with six strut positions and were installed within the 3.8m-deep excavation with the struts at the lowest height of 1.755m. After the base slab was cast, the struts were then raised to their second-highest position, a total upward movement of 1.08m.
This gave a strut clearance of 2.835m, sufficient to allow the installation of the culvert units beneath.
To pull the culvert sections together and create the required seal, the contractor used two culvert pullers, supplied by Groundforce Shorco and powered by three Instagrid 110V/32amp power packs purchased for the project.
Two of the power packs were used to run the pullers while the third was kept charged and ready for back-up.
The 13 Rolling Strut Boxes were installed end-to-end, allowing a total length of 45.5m to be opened at any one time. The boxes at the front of the run were then removed after backfilling and re-installed at the front of the next run in a rolling programme.
Conclusion
By tailoring its existing equipment to the specific on-site demands, Groundforce was able to provide a far more speedy and cost-effective solutions than the alternative sheet-piled method or intermediate steel posts and panels – both of which methods would have proved more complicated and time-consuming.