Soil Nailing Technique

Soil Nailing

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.

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IDEAL CONDITIONS FOR SOIL NAILING

Height of excavation

Excavation Face Inclination

Type of soil

Nail length

Nail inclination

Nail diameter

Grouted hole diameter

APPLICATIONS

Landslide Remediation

Railway embankments

Roadway widening under existing bridges

Stabilizing of existing retaining walls

Highway embankments and cuttings

ADVANTAGES

Temporary stand-up time

Excavation below the water level

Excavation in soft clay.

COMPARATIVE STUDY OF SOIL NAILING AND REINFORCED SOIL

Soil properties

Method of installing reinforcing elements

Construction process

Facing

Inclination of reinforcing elements