A recent development has been the introduction of multi-stage anchors. These improve efficiency and achieve high loads in poor ground through the use of multiple discrete unit bond lengths.
Anchor bores can be drilled using a variety of techniques. These include rotary, topdrive rotary percussive, down-the-hole hammer and augers. The type of drill rig used depends on the access, working room and ground conditions. Bar anchors are inserted into the bore and grouted in place. Multi-strand anchors are inserted, grouted and then post-tensioned to a set load.
Engineering steep slopes
Soil nailing is a slope stabilisation process that uses fully bonded ties installed in the ground. These are usually grouted bars, made from steel, stainless steel or glass fibre and can be solid or tubular.
Soil nails can be drilled in using a grout flush pumped through the centre, or pushed into or grouted into pre-drilled holes. Soil nails are then usually covered with mesh or geotextile, held in place with a bolted flat plate.
On highway embankments and rail cuttings, these mesh-covered slopes are commonly seeded, allowing vegetation and roots to stabilise the surface soils.
Long-term monitoring of full-scale structures has increased Cementation Skanska’s fundamental understanding of soil nail design. Load testing of soil nails is often a design requirement. We are experienced in carrying out manual and fully automated soil nail pullout tests.