Soil nailing is a technique used to reinforce and strengthen existing ground.Soil nailing consists of installing closely spaced bars into a slope or excavation as construction proceeds from top down.Soil nailing is a potential solution of landslide problems as it is economical and also applicable in seismic zones.It can solve the problem of residential area up to a great extent.It can be used in wide soil types.The grouted nails increases shear strength of overall soil mass.
TYPES OF SOIL NAIL
Screw anchor soil nail
Grouted soil nail
PROCEDURE OF SOIL NAILING
Excavate small cut
Drill hole for nail
Install & grout nail
Place drainage strips, initial shotcrete layer & install bearing plates
Repeat process to final grade
Place final facing on permanent walls
Soil nail wall construction proceeds from the top to bottom, and head plates are installed on each nail. Shotcrete or concrete is typically applied on the excavation face to provide continuity when a soil nail wall is constructed. For a soil nail wall the general construction procedure involves:
a) Excavate for the first nail (soil must be sufficiently self standing)
b) Install the 1st nail.
c) Construct 1st phase shotcrete on soil face (optional if shotcrete is constructed) with wire mesh or other reinforcement if required.
d) Install soil nail head plate (with or without other attachments)
e) Construct 2nd phase shotcrete (depending on staging specifications).
f) Excavate to next soil nail level, and install next soil nail, shotcrete etc.
g) Repeat steps through until the final excavation level is reached.
h) Construct additional permanent facing if required.
IDEAL CONDITIONS FOR SOIL NAILING
Height of excavation
Excavation Face Inclination
Type of soil
Grouted hole diameter
Roadway widening under existing bridges
Stabilizing of existing retaining walls
Highway embankments and cuttings
Temporary stand-up time
Excavation below the water level
Excavation in soft clay.
COMPARATIVE STUDY OF SOIL NAILING AND REINFORCED SOIL
Method of installing reinforcing elements
Inclination of reinforcing elements