DUCKBILL MECHANICAL ground anchors are securing highway embankments around Junction 29 of the M25 in Essex and on the A2 near Canterbury.
The anchors, specified by consultant WS Atkins, were supplied by WT Anchor systems and installed by its sister company WT Specialist Contracts.Main contractor for both of the projects was Carillion Highway Maintenance.
Anchors were installed in a number of areas along a 200m stretch of embankment on the M25.
Machine mounted breakers were used to drive 180 stainless steel Duckbill ground anchors with 20mm high yield bars between 6m and 8m into the clay to prevent the earth structure from slipping. Once installed each anchor was fitted with a 350mm load plate and set to a working load of 50kN.
On the A2 project, 60 anchors were driven 6m into mixed ground conditions of stiff chalk and silty clays in two sections on the same side of the road and set to working loads of 60kN. The installation followed careful long term monitoring of progressive creep tests to establish the stringent load testing requirement.