As part of the M23 Smart Motorways Programme, CAN Geotechnical Ltd were contracted to undertake embankment works for Kier Group between J8–J10 of the 18km stretch of the M23 near Gatwick Airport, to facilitate an all-lane running smart motorway.
The aim of the project was to widen the northbound segregated left turn on to the Gatwick spur towards Gatwick Airport, by
utilising the minimal space below. The existing embankment was regraded and stabilised using approx. 10,800m of DSI
epoxy coated and galvanised steel self-drilling hollow bar, extended through an 850m2 Maccaferri Terramesh reinforced
earth wall. This consisted of 3500m3 of compacted fill and layered geotextile, also known as the HRSSN slope (Hybrid
Reinforced Soil & Soil Nailed).
CAN installed 620no. hollow bar soil nails through the existing bank, which was later extended through layers of compacted
fill and tied to the front face using a formed plate, wedge boss and nut. The integration of the two separate systems and
near-highway working prohibited the use of large plant from behind (typical of these structures), resulting in bottom-up
working from the toe with small, manoeuvrable compaction plant to meet highways specifications.
Duration: 14 weeks
Client: Kier Group
Location: Reigate, Surrey