Services > Earth Retention > Soil Nailing
Soil Nailing
Soil Nailing is an in situ technique for reinforcing, stabilizing and retaining excavations and deep cuts through the introduction of relatively small, closely spaced inclusions (usually steel bars) into a soil mass, the face of which is then locally stabilized. A zone of reinforced ground results that functions as a soil retention system.

 

Soil Nailing Applications
  • Temporary and permanent excavation support/retaining walls
  • Stabilization of tunnel portals
  • Stabilization of slopes
  • Repair of retaining walls
Soil Nails May Consist of:
  • Reinforcing bars
  • Steel tubing
  • Steel angles
Types of Soil Nail
  • Driven nail
  • Grouted nail
  • Jet grouted nail
Soil Nailing Process
Corrosion Protection
Corrosion protection is necessary for long-term temporary and/or permanent works
  • Epoxy Coatings
  • Polyethylene Sheathing
  • Cathodic Protection
Types of Facing
The type of facing depends on application and soil type. Current facings include:
  • Shotcrete, generally reinforced with either
    • Welded wire mesh
    • Rebar
    • Steel or polyester fibers
  • Prefabricated concrete or steel panels
  • Cathodic Protection
Suitable Application Media
 
Soil nailing is possible in a wide range of materials including:
  • Clays
  • Sandy soils
  • Weathered rock; tallus slope deposits
  • Heterogeneous and stratified soils
Soil nailing is not practical in:
  • Soft, plastic clays
  • Organics/Peat
  • Loose (N<10), low density and/or saturated soils
  • Fills (rubble, cinder, ash, etc.)
Geotechnical Parameters and Design Considerations for Soil Nailing
  • Mechanical properties of soil
    • Soil type(s) and density
    • Moisture content
    • Soil stratification
  • Groundwater condition, seasonal changes and hydrology
Soil Nailing Drainage Systems
Drainage systems are incorporated into the nailed wall, reducing liquid pressure and preventing saturation of the reinforced ground. Drainage systems include:
  • Geotextile facing
    • Drilled in place relief wells
  • Slotted plastic collection piping
Surface drainage control above and behind the retaining wall is also critical to the system.

Soil Nailing Design Steps

1. Perform geotechnical site investigation
2. Evaluate excavation/nailed wall geometry
3. Check wall stability - internal/external
4. Incorporate drainage control system with nail wall design
5. Finalize nailing layout and work sequence
Soil Nailing Quality Control
  • Nailing installation sequence
    • Verification testing - pull test to verify design strengths
    • Progressive monitoring for design performance
  • Conventional movement monitoring
    • Inclinometers
    • Optical survey of fixed targets
  • Shotcrete
    • Thickness
    • Strength
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