Soil Nailing

Soil nailing is a construction remedial measure to treat unstable natural soil slopes or as a construction technique that allows the safe over-steepening of new or existing soil slopes.

It consists of installing closely spaced bars into a slope or excavation as construction proceeds from top down.

It is an effective and economical method of constructing retaining wall for excavation support, support of hill cuts, bridge abutments and high ways. This process is effective in cohesive soil, broken rock, shale or fixed face conditions.

Origin

Soil nailing evolved from the New Austrian tunnelling method, which is a system for underground excavations in rock. This method consists of passive steel reinforcement in the rock followed by the application of reinforced shotcrete. This concept of combining passive steel reinforcement and shotcrete has also been applied to the stabilization of rock slopes since the early 1960s.

The United States first used soil nailing in 1976 for the support of a 13.7 m deep foundation excavation in dense silty sands.

The first application of soil nailing was implemented in 1972 for a railroad widening project near Versailles, France.

Application

• Stabilization of railroad and highway cut slopes

• Excavation retaining structures in urban areas for high-rise building and underground facilities

• Tunnel portals in steep and unstable stratified slopes

• The stabilizing of existing over-steep embankments.

• Soil Nailing through existing concrete or masonry structures such as failing retaining walls and bridge abutments to provide long term stability without demolition and rebuild costs.

• Temporary support can be provided to excavations without the need for bulky and intrusive scaffold type temporary works solutions.