Temporary works specialist Altrad RMD Kwikform (Altrad RMDK) has delivered a ground shoring system for the construction of London One, a 41,300 sq m data centre development in Slough.
Altrad RMDK worked with contractor O’Halloran and O’Brien (OHOB) to develop a robust temporary works solution to support the excavation works required for three large cofferdams.
These structures were necessary to facilitate the installation of attenuation tanks. Altrad RMDK said the project’s complexity – driven by the site’s scale, logistical constraints, and structural requirements – made it a challenging undertaking.
Two of the cofferdams formed a continuous run of over 190m, which required heavy excavation and careful design, particularly around ground movement, load transfer and structural support.
The depth and length of the excavation, with a requirement to maintain ground deflection within a strict 15mm limit, needed a high-capacity engineered shoring solution. This deflection limit was critical due to a live gas main running just 8m from the sheet piles on the northern perimeter.
The available working area within the site was also constrained. Despite the large footprint, high volumes of materials and equipment meant there was limited space for temporary works installation and handling. This made the logistics of equipment delivery, positioning and removal an important design factor, requiring close coordination between the companies involved and efficient use of space and time.
Hybrid solution
To overcome these challenges, Altrad RMDK undertook detailed engineering analysis and a ground movement assessment to inform the temporary works design. A hybrid solution incorporating the company’s GeoBrace and Tubeshor systems was developed, based on the expected ground conditions, surcharge loading and service constraints.
Tubeshor was specified for internal support due to its axial load capacity and high axial stiffness, making it particularly well-suited to the demands of heavy-duty cofferdam applications. Its ability to isolate and lock off the hydraulic element once preloaded provided a robust and stable support system, essential for maintaining excavation integrity across wide spans. The high stiffness of the system also ensured minimal movement under load, a critical requirement in maintaining deflection limits near sensitive infrastructure.
By spanning wider bays, Tubeshor reduced the number of props required within the excavation, helping to alleviate site congestion and to simplify logistics in an already constrained working area. Furthermore, the system’s ease of installation and removal allowed the entire cofferdam support to be installed within a day.
Altrad RMDK said the use of hydraulic jacks facilitated rapid setup and dismantling, saving time, reducing labour costs, and further minimising site congestion.
Adaptability essential
GeoBrace was deployed around the perimeter, selected for its adaptability in large or irregular cofferdam layouts, an essential requirement given the 190m continuous run. Its twin-pin joints and articulated corners allowed for precise alignment across varying angles, while maintaining full structural continuity.
The system’s design eliminates any reduction in allowable bending moment at the joints, which helped control deflection near sensitive areas such as the adjacent gas main.
Altrad RMDK’s in-house engineering team worked with OHOB from the outset, producing detailed design calculations, layout drawings and installation sequencing plans. The company said this proactive engagement ensured the temporary works solution was fully integrated with the wider construction programme.
