08.04.08
Van Elle stabilise Willenhall embankment
Van Elle recently carried out piling works to improve the stability of an existing 10m high Network Rail embankment at Willenhall, Coventry, West Midlands for clients Story Rail.
This was no ordinary job as the Bromsgrove sandstone ground conditions made drilling the CFA piles a real challenge. As well as the demanding ground conditions Van Elle had to work within the usual clearances from railway traffic, overhead line electrification and work on a 7.5m wide, 5m high piling platform.
The embankment at Willenhall has shown evidence of a deep seated rotational failure. Using good asset management practice a feasibility scheme was developed to significantly reduce the risk of future movement. The chosen option of piling plus rock-filled shear key was designed to improve the slope stability of the embankment.
Piling works consisted of 220No. 450 mm diameter CFA (continuous flight auger) piles drilled to depths of 10m - 12m. CFA piles were designed for this project as bored piles would have been a much slower operation and driven piles would not penetrate the Bromsgrove sandstone. The piles were reinforced using standard longitudinal reinforcement with helical links.
The tough Bromsgrove sandstone meant that a customised auger for the piling rig was required and Van Elle’s expert fabricators built a 450mm diameter, 1.5m auger with cutting teeth and rock cutters in house. This ensured that the necessary penetration of the sandstone was achieved by the rig on site.
Access on site was also a challenge. The piling design and installation had to take into account that only one side of the embankment was accessible and the Soilmec 208 piling rig had to work from a 7.5m wide, 5m high piling platform running adjacent to the track for some 220m.
Ian Jones, Van Elle’s construction director, said: “Because we’re Link-up approved and we’ve been doing this type of work for so long, we know and work within all the health and safety requirements. We also know the commercial realities of rail projects and always work hard to manage jobs whatever the on-site challenges might be.”
Despite the conditions and the live track the job was managed within the schedule and came in on budget.
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