The foundation works for the Shakespeare Primary School comprise driven steel tube piling, drilling and grouting of shallow mine workings beneath the main school building, and soil nailing to the car park and nursery retaining walls.
Firstly, Aarsleff will be drilling 109no vertical bores on a radial grid including casing under the school building with its Boart and Klemm 806 rigs. Aarsleff will then mix and inject OPC/PFA grout to the 4500m2 area, ensuring that any surface instability due to these shallow workings, is eliminated.
Aarsleff's second remit of work includes the design and installation of soil nails, which will follow a top-down construction with a soil nail spacing of 1.5mX1.5m. Prior to the main works, suitability tests of 4no positions will take place to confirm the ultimate bond stress used in the design.
To facilitate the car park's retaining wall, Aarsleff will employ its Boart AJ18 rig to install 105no soil nails of 5.5m average length to the 205m2 vertical wall area. For the nursery retaining wall, Aarsleff will install 64no soil nails of approximately 5m in length to the 115m2 vertical wall area. Each of the R32-280 galvanised epoxy-coated bars will be fitted with a head plate, and the face will be clad with a stone-filled mesh basket using local stone to blend with the existing stonework of the area. Acceptance testing of two nails randomly selected from each wall will be undertaken concurrently with the main works to confirm satisfactory performance at working load.
Aarsleff's final remit of work includes the driven steel tube piling. Aarsleff will be utilising its Junttan PM20 rig to drive 411no thick-walled steel tube piles of varying lengths between 3m and 14m. Aarsleff will also carry out dynamic proof load testing and vibration monitoring during the works.
Grout, soil nailing and piling works are due to finish in early October 2017.
Aarsleff is also currently undertaking a similar steel-driven pile solution for BAM Construction on Bannerdale, a new-build secondary school a mile south of Sheffield city centre.