Soil nailing is an economic, top-down earth retention method in residual or highly cohesive soils. Closely spaced reinforcing bars (nails) are installed in the face of the excavation. A structural concrete fascia bridges the nails and supports the soil/rock between nails. Soil nails are passive elements that become tensioned when the soil/rock deflects laterally as excavation depth increases.
Soil nail walls can be a temporary measure for support of excavation or structural underpinning, or they can function as permanent retaining walls or slope stabilization systems. This technique is most advantageous in difficult soil conditions such as cobbles, boulders or weathered rock, where space or headroom is limited, and a permanent wall is required.