The Harbour, Ground Stabilisation

Lancashire NHS Trust

The Harbour, Ground Stabilisation

  • The Harbour, Blackpool, Lancashire
    Lancashire NHS Trust
    Alan Johnston Partnership
    Vinci Construction
    E’Grid™ 20/20
    34,000m 

  • In order to enable construction to begin on a new adult mental health hospital at Whyndyke Farm, Blackpool the use of Wrekin Products’ E’Grid™ 20/20 biaxial geogrid was required. The new £39.5M state-of-the-art facility will have 154 beds and will replace wards currently used on two separate hospitals in Blackpool and Lytham.

    Construction began in April 2013 and will take 18 months to complete with ‘The Harbour’ becoming operational in early 2015.

    To enable construction of the new hospital a ‘cut and fill’ operation was undertaken to create the required site footprint. The other issue to address was that the in-situ soils had insufficient strength to support the loads imposed by the various construction plant that would traffic the site during construction.

To overcome this, the entire site was blanketed by a layer of E’Grid™ 20/20 geogrid with compacted stone above. Grid continuity was provided by ensuring adjoining rolls had a minimum overlap of 300mm.

Compaction of the stone into the geogrid apertures reinforces the soil by creating a mechanical interlock where the soil is laterally restrained by the E’GridTM geogrid.

The footprint of the building also posed access issues to the project team, with the hospital building itself founded on a grid of 97 15m long reinforced concrete piles. In this area a piling mat, or working platform, was required to support the additional loads imparted by the SF-50 CFA piling rig.

To undertake the necessary indemnified design, and provide the required Working Platform Certificate, Wrekin utilised the services of specialist geotechnical designer PaSCoE Ltd. The design again utilised the E’Grid™ 20/20 geogrid but with an increased depth of compacted stone. Although the E’GridTM geogrid was only required for the construction phase of the project, and does not form part of the permanent solution, its use provided the project team with a cost effective engineering solution to their access issues.

Wrekin Products’ range of E’Grid biaxial geogrids have been designed to optimise the key properties of rib form, durability and tensile properties. They are produced from polypropylene on the world’s first fully integrated geogrid production line and are manufactured by punching and stretching, in two directions, a high quality virgin polypropylene extrusion in closely controlled factory conditions. This ensures that the resulting product has high tensile stiffness enabling working loads to be developed at very low levels of strain.