A joint venture of May Gurney and Systems Geotechnique has completed foundation strengthening works the Leeds to Manchester Airport rail link at Standedge Tunnel.
Work undertaken under the Railtrack May Gurney Structures Partnership was completed during weekend possessions. This included installation of 100 vertical 250mm diameter piles below the tunnel sidewalls. The 6m long pile bores were reinforced with 220mm diameter steel tube and then filled with grout.
The Victorian tunnel is built in generally hard and competent rock, but a weathered, faulted zone is prone to creep. The new piles help underpin the existing masonry arch, but have the capacity to support a new arched tunnel lining system should conditions continue to deteriorate, explains May Gurney northern piling manager James Blackwell.
The joint venture used two mini pile rigs with down the hole hammers. Each rig worked double shifts within the possession period to ensure completion within the nineweek contract programme.
The joint venture limited congestion within the tunnel by keeping as much ancillary equipment as possible outside the tunnel. This involved fixing dedicated lighting cables, airlines and water hoses ahead of the main production work.