DYWIDAG SYSTEMS International has supplied MAI hollow bar soil nails to stabilise a railway embankment in Grantham, Lincolnshire.
An embankment slip had reduced the twin track section between Allington Junction and Barkstone East Junction to a single line.
To stabilise the silty clay embankment and prevent any further slips, contractor Birse Rail installed two layers of nailed gabion baskets at the base of the slope.
The soil nails were installed into weak mudstone beneath the embankment and terminated at the face of the gabions with wedge washers and bearing plates.
The hollow bar soil nails were installed using a simultaneous drill and grout method.Grout was injected along the entire length of the borehole as the nail was drilled in.
An injection adaptor just below the drive-head of the drilling rig comprises a stationary grout bottle with an internal rotating shaft. Grout is pumped into the chamber of the bottle and then passed into the borehole via inlet ports.
The rotary injection adapter enabled drilling and grouting to be combined as a single operation, leading to faster construction, says Dywidag.
Granular material was placed behind the gabions following nailing and the collapsed section of track reinstated, allowing normal train services to be resumed.