Soil Nailing & Shotcrete Walls
In soil nailing, steel bars are drilled and grouted into the soil as an excavation is dug from the top down. Shotcrete (sprayed concrete) is then applied to the face. Workers spend their day next to an open vertical cut, so the face must be watched and the sequence followed carefully.
- Excavation
- Foundation Crews
- Concrete
How it works
- Excavate a short lift, typically a few feet, and expose a vertical face.
- Drill holes into the soil and insert steel bars (nails).
- Grout the nails and place mesh or rebar.
- Spray shotcrete onto the face. Repeat for the next lift down.
An engineer designs the wall. Work must follow that design and sequence, as required for protective systems. See Protective Systems.
Hazards
- Soil face collapse before the nails and shotcrete are in. See Cave-In Warning Signs.
- Drilling hazards: rotating rods, noise, pinch points, and underground utilities.
- Grout and shotcrete: high-pressure hoses, hose whip, skin burns from wet cement and eye injuries.
- Silica dust and rebound from spraying and finishing. See Silica.
- Surcharge loads such as equipment and stockpiles near the edge. See Surcharge Loads.
- Falls from the top of the wall or from work platforms.
Safe practices
- Follow the engineer's lift height, nail pattern and timing. Do not leave a face open longer than allowed.
- A competent person should inspect the face before and during each shift, and after rain or other changes. Watch for cracks, bulging, seepage and movement.
- Keep workers out from under unsupported faces. Work from a protected position and keep a clear escape route.
- Use whip checks and secure hose couplings on pressurized lines. Keep the nozzle operator and helpers in agreed positions with clear signals.
- Wear eye and face protection, waterproof gloves and boots, hearing protection and a respirator for dust.
- Wash skin quickly if it contacts wet concrete or grout. Alkaline cement can cause chemical burns.
- Keep loads, vehicles and spoil back from the edge.
- Do not point the nozzle at anyone.
- Do not start work under an excavation face until the competent person approves.
Standards & references
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