Soil nails are slender structural elements used for reinforcing the ground/rock mass. They are applied in permanent and temporary support systems stabilizing slopes, landslides and retaining structures as well as in tunnelling.
Soil nails are typically:
• vibrated bars or steel rods;
• bars installed in pre-drilled holes,
• non-recoverable bars/rods of self-drilling elements.
Soil nails transfer tension and compression loads. They are passive anchoring components without free length and pre-stressing. In order to mobilize forces in soil nails, soil/rock mass deformation is necessary. The soil nailing technology should be defined in the design and adapted to the soil conditions. In case of aggressive soil conditions it may be necessary to apply double corrosion protection (DCP), since grout protection (single corrosion protection, SCP) might prove insufficient.
Soil nails are installed with standard rotary high-impact drilling rigs or caterpillar vibrators. In case of drilled soils, the bars/rods are grouted into the ground/rock mass with cement grout with a strength of min. 35 N/mm2 or other required in the design. The soils are drilled with air or water flush and in the event of any problems with stability, casing pipes or a grout flush (cement grout with an approx. 0.7 w/c ratio are used. The drilled hole is finally filled with cement grout with an approx. 0.4 w/c ratio. The nail head has the form of a bearing plate fixed to the rod or bar with a screw nut. Then the bearing plate is positioned on a reinforcing mesh or any other surface protection in accordance with the design.
Soil nails are installed in accordance with the requirements of PN-EN 14490. Execution of special geotechnical works – Soil nailing.