St Modwen Park, Burton is a new 64-acre business park strategically located adjacent to the A38 at the entrance to Burton-upon-Trent. The site has been under development since 2015 and is helping to strengthen the East Midlands’ already strong position in logistics and distribution. The development has taken place in several phases over the last decade and was completed in 2015.

Aarsleff has been heavily involved throughout the development of St Modwen Park in Burton. We installed 1281 precast concrete piles in 2019 to form the third phase of development and 2612 precast concrete piles in 2023 for the first part of the fourth phase.

Therefore, when we were asked by Winvic Construction to enter into discussions on units B79, B58 and B41 at St Modwen Park, Burton Phase 4 and 5, we had extensive experience in this area and a good understanding of the ground conditions.

Two solutions were proposed: a solution using precast concrete driven piles similar to the one we had previously installed, and a soil improvement package by installing rigid inclusions.

The latter proposed rigid inclusions with a nominal diameter of 300 mm installed in a designed grid layout to meet the loading specifications of the soil support slab and to achieve a soil improvement that meets the project performance specifications, as well as rigid inclusions for the foundations of the structural slabs.

The two solutions were as follows:

The rigid containment solution was chosen and 3453 of them were installed in the 3 units to a depth of 9.0 m through reclaimed soil and PFA fill found in the natural claystone layers. One of the advantages of rigid containment is rapid production. Over 100 can be installed per day, with follow-up work to trim and restore the load transfer platform also taking place during the same work shift. The containment was installed using Liebherr high torque AGE pile drivers and custom-made displacement tools from Aarsleff’s own factory and fabrication workshop.

The tool was developed after testing a commercially available solution that was consistently causing concrete blockages and interrupting production. So the plant team began designing and manufacturing a range of displacement tools that met our site’s feedback and specifications. The result was more efficient drilling times and fewer blockage issues, all contributing to increased daily production.

During installation, the containment columns were tested using plate load tests (PBT) to confirm design requirements and ensure compliance with the model generated by Plaxis, coordinated by Aarsleff’s in-house design engineers. In addition, a series of dummy foundation tests were performed on each individual unit to confirm the overall performance of the system.

The depth of the PFA fill was also closely monitored during the site works to ensure that the target installation depths met the foundation layer requirements, which in turn fed into the design assumptions to ensure that the grid spacing was appropriate for the soil conditions encountered. In parallel, concrete cube tests were carried out to confirm that the concrete strength requirements were met as per specification. A full validation report was produced on completion of the works.

For more information, see Aarsleff Ground Engineering. This article was paid for by Aarsleff Ground Engineering.

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