Main contractor Laing O’Rourke is in the early stages of a £300m contract to build a huge cancer research facility at Littlemore House, part of the Oxford Science Park.
The scheme involves refurbishment and extension of the existing Littlemore House and construction of a new building for the Lawrence J. Ellison Institute for Transformative Medicine.
The new 300,000 sq ft Ellison Institute building, designed by Foster & Partners, covers an irregular footprint and will sit on top of an extensive basement complex.
Laing O’Rourke has enlisted Groundforce Shorco to design and supply a complex temporary works structure to support the excavation’s secant-piled retaining walls during construction of the basement.
Due to the high lateral loadings and long spans required, Groundforce Shorco has specified a combination of MP250, MP375 and MP750 hydraulic props (with maximum load capacities of 250, 375 and 750 tonnes respectively).
Individual prop loadings on this project vary from 140kN/m to 780kN/m SLS.
Groundforce Shorco contributed crucial input at the design stage, working closely with Laing O’Rourke to overcome clashes with the permanent structures – columns, core walls and slabs – and modifying the propping arrangement accordingly.
The props, together with lengths of Super Mega Brace modular frame, are being installed in a phased operation in five separate zones within the large excavation.
In Zone 1, five MP250 props were installed around the perimeter of the excavation in November 2024, three spanning the excavation and two installed as knee-braces to support the end of the excavation. The props, ranging in span from 7.9m to 15.6m, remained in place until Laing O’Rourke had completed the basement slab and the retaining walls were self-supporting. These five props were off-hired in March this year.
Zone 2, at the opposite end of the excavation, employed the longest prop, a 30m-long MP375, and the two strongest props, both MP750s, in addition to six MP250 props. The two MP750 props, one spanning 15.7m and the other 23m, support the scheme’s maximum loadings of 780kN/m SLS.
All six props in Zone 2 were installed as raking props, bearing against a Super Mega Brace frame installed along the concrete-piled retaining wall and transferring the loadings to concrete thrust blocks cast into the base of the excavation. The Zone 2 props were installed in November 2024 and removed in April 2025.
Zone 3 is ranged around the central section of the basement excavation and includes the deepest part of the excavation, extending to 10m. Here, six MP250 props are installed as raking props, transferring lateral loads from the capping beam on top of the perimeter wall to the basement slab cast in the middle of the excavation. Special bird’s-mouth adaptors cast into the concrete secure the props at either end.
This zone is three-sided, meaning that knee-braces are required in both corners. The longer props are MP375s (spanning between 20m and 22m across the corner; the inner props, spanning approximately 10m, are MP250s. Here, the depth of the excavation requires two levels of props.
Zones 4 and 5 have yet to be installed. Zone 4 will be a straightforward corner-brace, with two MP250 props bearing against Super Mega Brace beams to support the piled retaining wall. Zone 5 is a rectangular section measuring approximately 34m in length and 12.3m in width and with an opening leading to the main excavation along one side.
This is supported by seven MP250 props: three spanning the 12.3m width and two acting as knee-braces at either end of the section. The two knee-braces in the corner facing the opening will be installed at a lower level, acting against Super Mega Brace beams suspended from the concrete piles with gallows bracket. The other five props will brace the capping beam on top of the piled retaining wall.
“The geometry of this site is complex, with props positioned at multiple locations,” says Groundforce Shorco senior engineer Ahmed Adayem. “There are five zones and each one is different in dimension, ranging from about 15m by 25m in Zone 1 to 55m by 55m in Zone 3. The overall site is around 105m by 140m.”
The complexity of the site, coupled with the calculated loadings and strict deflection criteria, meant that load monitoring was a crucial factor in the temporary works design. Hence more than half of the props – 20 in total – were fitted with Groundforce Shorco’s remote load monitoring system.
This uses a special load pin, incorporating a strain gauge, within the end swivel connection of the prop. The signal from the load pin is sent to a battery-powered acquisition module which then transmits a reading to a remote computer or hand-held device. Loads can thus be monitored in real time and the system calibrated to automatically send an alert if a pre-determined load value is exceeded.
The highest loadings are concentrated in Zone 2, where the two MP750 props were installed. Load monitoring here was especially important due to the close proximity of a listed building.
The temporary works design required a great deal of attention to detail to ensure the propping system aligned with the construction sequence. And despite the complexity of the task, Groundforce Shorco was able to supply all the necessary equipment from its standard range of products, meaning there was no need for bespoke beams or props.
“This approach allowed us to meet the project’s requirements efficiently while keeping the solution within the available range of Groundforce Shorco equipment,” says Ahmed. “Our standardised equipment reduced complexity and improved on-site efficiency.”
He adds: “The proximity of the listed buildings and permanent works required meticulous planning – and that’s where we rose to the challenge. It was a seamless integration of safety, precision and logistical excellence.”