Soil nailing is a technique in which soil slopes, excavations or retaining walls are reinforced by the insertion of relatively slender elements - normally steel reinforcing bars. The bars are usually installed into a pre-drilled hole and then grouted into place or drilled and grouted simultaneously.
They are usually installed untensioned at a slight downward inclination. A rigid or flexible facing often pneumatically applied concrete otherwise known as shotcrete or isolated soil nail heads may be used at the surface.
Soil nailing is an economical technique for stabilizing slopes and for constructing retaining walls from the top down. This ground reinforcement process uses steel tendons which are drilled and grouted into the soil to create a composite mass similar to a gravity wall. A shotcrete facing is typically applied, though many architectural options such as precast panels or "green" vegetated cells are available for permanent wall facings.
Soil Nailing or Shot Crete Advantages:
- Used to follow irregular curves.
- Equipment is portable for tight spaces.
- The technique is flexible, easily modified.
- Creates less noise and traffic obstructions.
- Less impact on nearby properties.
- Requires minimum shoring space.
Soil nailing was originally introduced in France in the 1970s. Soil nailing can be used for building excavations or for stabilizing existing slopes that have a history of problems. It’s a procedure to reinforce and strengthen ground adjacent to an excavation by installing closely spaced steel bars called “nails” ,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 effectively in cohesive soil, Broken rock, shale or fixed face conditions.
- 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
- construction and retrofitting of bridge abutments with complex boundaries involving wall support under piled foundations
- Stabilizing steep cuttings to maximize development space.
- 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
MACHINERY USED FOR SOIL NAILING
- Drilling Equipments
- Grout Mixing Equipments
- Shotcreting / Guniting Equipments
MATERIALS USED FOR SOIL NAILING
- Steel Reinforcements
- Grout Mix
- Shotcrete/ Gunite
preparation for soil nailing
This initial excavation will be carried out by trimming the original ground profile to the working platform level where the first row of soil nails can be practically installed. The pre-requisite of this temporary excavation shall be in such a way that the trimmed surface must be able to self support till completion of nail installation. Sometimes, sectional excavation can be carried out for soil with short self support time. If shotcrete/gunite is designed as facing element, the condition of the trimmed surface shall be of the satisfactory quality to receive the shotcrete.