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Soil Nailing
The use of soil nails within the UK has increased significantly in recent years as they have become progressively more popular as a geotechnical process/tool ideally suited to providing support to failing slopes, notably existing rail and highways embankments. Nails can be used to "pin" a wedge of failing slope to the intact soil beyond the existing or potential slip plane.
May Gurney Geotechnical provide a complete design and construct service and install various diameters and lengths of self drilling hollow stem grouted bars which are installed using a drill head and mast mounted either on a standard 16t 360º excavator or a small drilling rig, in a very similar manner to the installation of ground anchors.
The hollow steel bar has a continuous thread running along its external wall for the entire length of the bar and is fitted with a suitable expendable drill bit. Additional lengths of bar can be introduced during drilling and coupled together in order to achieve the required overall nail length. Grout is continually injected through the hollow bar whilst drilling and is ejected from apertures in the cutting head creating a continuous low pressure scouring action against the sides of the drill hole, which in turn creates a very rough, irregular shaped grout body. The grouting pressure forces the grout and soil cuttings back along the outside of the bar such that all the cuttings are flushed out from the drilled hole leaving a monolithic grouted annulus and a strong integral stabilising structure with an enhanced interlock/mechanical bond between the grout and the soil.
On completion of installation of the nails, a plastic coated steel wire mesh
geotextile is laid on the surface of the slope prior to the positioning of the
nail head plate, retaining nut and tensioning. The mesh is designed to assist
in the retention of the soil between the nails, which are typically spaced at
1.5m - 2.5m centres, such that the nails act in unison rather than individually.
Download Soil Nailing pdf file
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