Soil Reinforcement by Nailing: University of Kirkuk Civil Engineering

University Of Kirkuk
Civil Engineering
Soil reinforcement by nailing
Supervised By:
Fouad Al-Jalaby
Prepared By:
Abdulrahman Mohammed Saeed
1
INTRODUCTION
Soil Nailing is a technique 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, The nails
are subjected to tension compression, shear and bending moments.
Figure 1
HISTORY OF SOIL NAILING
 Technique came from New Austrian Tunneling Method in 1960.

 Stabilization works in underground tunnel in Europe in 1970.
 The first recorded use of soil nailing in its modern form was in France in 1972.
 The United States first used soil nailing in 1976 for the support of a 13.7 m
deep foundation excavation in dense silty sands.
2
FAVOURABLE GROUND CONDITIONS
 Critical excavation depth of soil is about 1-2 m high vertical or nearly

vertical cut.
 All soil nails within a cross section are located above groundwater table.
 FAVOURABLE SOILS Stiff to hard fine-grained soils, dense to very
dense
granular soils with some apparent cohesion, weathered rock
with no weakness planes and glacial soils etc.
 UNFAVOURABLE SOILS Dry, poorly graded cohesion less soils, soils
with cobbles and boulders, soft to very soft fine-grained soils, organic soils.
APPLICATIONS
 Stabilization of railroad and highway cut slopes.
Figure 2
 Excavation retaining structures in urban areas for high-rise building and
underground facilities.
Figure 3
3
 Existing concrete or masonry structures such as failing retaining walls and
bridge abutments.
Figure 4
 Tunnel portals in steep and unstable stratified slopes.
Figure 5
 construction and retrofitting of bridge abutments.
 Stabilizing steep cuttings to maximize development space.
Figure 6
4
NAILS
 Driven Nails
 Grouted Nails
Corrosion
 Protected nails
 Jet grouted Nails
 Launched Nails
Figure 7
CONSTRUCTION
SEQUENCES
 Initial Excavation
 Drilling of Holes (Figure 8)
 Nail Installation
 Grouting
 Place Reinforcement and Drainage
Figure 8
 Shotcreting And Installing Bearing Plates (Figure 9)

 Repeat Steps to Final Subgrade
 Permanent Facing
Figure 9
ADVANTAGES
 With the right soil and site conditions, a rapid and economical means of
constructing earth retention support systems and retaining walls.
 Shorter drill holes.
 Smaller diameter bars at shorter lengths.
 Retaining walls are secured laterally into the soil, eliminating piles and
foundation footers.
 Grouting only once is required, saving time and labor.
 The technique is flexible, easily modified.
 Creates less noise and traffic obstructions.
 Less impact on nearby properties
 Allow in-situ strengthening on existing slope surface with minimum
excavation and backfilling, particularly very suitable for uphill widening,
thus environmentally friendly.
5
 Allow excellent working space in front of the excavation face.
 Can be used for strengthening of either natural slope, natural or man-
made cut slopes
DISADVANTAGES
 Nail encroachment to retained ground rendering unusable underground

space.
 Generally larger lateral soil strain during removal of lateral support and
ground surface cracking may appear.
 Tendency of high ground loss due to drilling technique, particularly at
course grained soil.
 Less suitable for course grained soil and soft clayey soil, which have short
self-support time, and soils prone to creeping.
 Suitable only for excavation above groundwater.
CONCLUSION
 Since this process is effective in cohesive soil, broken rock, shale, or mixed
face conditions it permits flexibility to conform to a variety of geometric
shapes to meet specific site needs.
 Due to its rather straightforward construction method and is relatively
maintenance free, the method has gained popularity in India for highway and
also hillside development projects. Soil nailing is an economical means of
creating shoring systems and retaining walls.
REFERENCES:
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University Of Kirkuk

Soil reinforcement by nailing

Soil Nailing is a technique to reinforce and strengthen ground adjacent to an

HISTORY OF SOIL NAILING

 Technique came from New Austrian Tunneling Method in 1960.

 Critical excavation depth of soil is about 1-2 m high vertical or nearly

 Shotcreting And Installing Bearing Plates (Figure 9)

 Nail encroachment to retained ground rendering unusable underground

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