This document summarizes a seminar presentation on soil nailing, which is a technique used for stabilizing slopes and excavations. It introduces soil nailing and discusses favorable conditions, materials used, the design and construction process, applications, cost advantages, and limitations. Key points covered include that soil nailing involves inserting steel reinforcing bars into slopes and filling them with grout to improve stability, it is most suitable for weathered rocks and glacial soils above the water table, and provides a cost-effective alternative to retaining walls for excavations.

1. THE NATIONAL INSTITUTE OF ENGINEERING , MYSORE-08
Dept. of civil engineering
SEMINAR
TOPIC : SOIL NAILING (an area of study in geotechnical engineering )
PREPARED BY : ABDUL SATTAR
USN: 4NI16CV001
GUIDED BY : Dr. N. SURESH (HOD, DEPT. OF CIVIL ENGG.)

2. CONTENTS :
INTRODUCTION
 A BRIEF NOTE
 FAVORABLE AND UNFAVORABLE CONDITIONS
 MATERIALS USED IN SOIL NAILING
 DESIGN
 CONSTRUCTION
 APPLICATIONS
 COST COMPARISON
 ADVANTAGES AND DISADVANTAGES
CONCLUSION AND REFERENCES

3. INTRODUCTION :
 Soil nailing is a technique of in-situ ground reinforcement.
 It is widely used for stabilizing foundations, pit excavations and
permanent slopes.
 Soil nail can help reinforcing the slope, thereby improving the
stability of the slope.
 Historically, this technique was for the first time used in 1972 in
the slope excavation of Versailles railway in France and was a
success. Soon after, the technique obtained rapid development.

4. Fig. Illustration of Soil Nailing

5. A brief note :
 Soil nailing is a constructional remedial measure to treat unstable
natural soil slopes.
The technique involves the insertion of reinforcing elements into
the slope – often general purpose reinforcing bars(rebar) of solid or
hollow type are used.
To proceed further, a preliminary analysis is done to determine if
the soil nailing would be an effective retention technique. For this
purpose, four main points are considered.
1. First, the existing ground conditions should be examined.

6. Continued:
2. The advantages and disadvantages for a soil nail wall should be
assessed for the particular application being considered.
3. It is to be kept in mind that all soil nails should be located above
the groundwater table.
4. The cost of the soil nail should be considered.

7. Favorable and unfavorable conditions:
 The most favorable conditions for soil nailing are as follows:
I. The soil should be able to stand unsupported one to two meters
high for a minimum of two days when cut vertically.
II. All nails within a cross section should be located above the
groundwater table.
 The most suitable soils for soil nailing are weathered rocks(rock
with no weak planes) and glacial soils.

8. Continued:
 A list of unfavorable conditions for soil nailing are-
i. Dry or poorly graded cohesion-less soil
ii. Soils having a high groundwater table
iii. Soils containing cobbles and boulders
iv. very soft fine-grained soils
 Other difficult conditions include exposure to freezing
temperatures and granular soils that are very loose.

9. Design:
 After a preliminary analysis of the site, initial designs of the soil
nail wall can begin.
 Initial design considerations include wall layout(wall height and
length), horizontal and vertical spacing of nails, soil nail pattern on
wall face, soil nail inclination, soil nail length and nail material.
Nail length, diameter and spacing typically control external and
internal stability of the wall.

10. Materials used in Soil Nailing:
 Steel Reinforcement: Steel reinforcements are used in the
construction of soil nail walls.
 For corrosion protection, all steel components shall be galvanized.
 For this purpose, zinc based coating is applied onto the soil nail
thread.
 For double corrosion protection, the PVC corrugated pipe of good
quality and adequate thickness is used.

11. Fig. Steel Reinforcements used in Soil Nailing

12. Continued:
 Grout Mix: Grout mix is a highly fluid mix formulated specially for
soil nailing applications.
 For conventional soil nail, the water cement ratio of the grout mix
ranges from 0.4 to 0.5.
 As most cementitious grout will experience grout shrinkage, non-
shrinking additives are used to reduce bleeding and grout shrinkage.

13. Fig. Grout is being applied through pipes

14. Continued:
 Shotcrete: Shotcrete can be continuous flow of mortar or concrete
mixes.
They are projected perpendicularly onto the ground surface.
 It is achieved by means of
I. pneumatic blowing for dry mix
II. Spraying for wet mix

15. Fig. A layer of shotcrete being applied on the wire mesh

16. Construction:
 Most soil nail wall construction follows a specific procedure. First a
cut is excavated and temporary bracing is put in place. This is done
with conventional earth moving equipment and hydraulic drills.
 Next, holes for the soil nails are drilled at predetermined locations.
 With the holes drilled, the next step is to install and grout the nails
into place. After all the nails are inserted, a drainage system is put
into place.
 A layer of ‘SHOTCRETE’ is applied and bearing plates are installed
before a final facing is put in place to complete the soil nail wall.

17. Construction procedure:

18. Applications:
 Stabilization of railroad highway cut slopes.
 Excavation of retaining structures in urban areas for high-rise
building and underground facilities.
 Tunnel portals in steep and unstable stratified slopes.
 Stabilizing steep cuttings to maximize development space.
 Stabilization of existing over-steep embankments.

19. Applications:

20. Cost comparison:
 One great advantage of soil nail walls is their cost-effectiveness
over other alternatives.
 When conventional soil nailing construction procedures are used,
soil nail walls are much more economical than concrete walls.
 They are also more cost effective as compared to ground anchor
walls.

21. Advantages:
 Less impact on nearby properties.
 Allows in-situ strengthening on existing slope surface with
minimum excavation.
 Allows excellent working space in front of the excavation face.
 Can be used for strengthening of either natural slope, natural or
man-made cut slopes.
 The technique is flexible, easily modified.

22. Disadvantages:
 Generally, during removal of lateral support, ground surface
cracking may appear.
 Tendency of high ground loss due to drilling , particularly at coarse
grained soil.
 Less suitable for coarse grained soil and soft clayey soil, which
have short self support time, and soil is prone to creeping.
 Suitable only for excavation above groundwater.

23. Conclusion:
 Soil nailing is an accepted technology.
 The theoretical aspects of this technique are well understood and
well reported in technical literature.
 However, research indicates that there are few practical guidelines
available that offer a comprehensive, experience-based insight into
the construction considerations that should be addressed before a
soil nail system design is finalized and implemented.

24. References:
 http://www.deepexcavation.com/en/soil-nail-wall
 http://www.moretrench.com/b literature article.php
 http://en.Wikipedia.org/wiki/soil nailing
 Geotechnical engineering circular no.7: Soil nail walls (pdf)(report).
FHWA.2003. FHWA-IF-03-017.
 Image sources: Internet.