The document discusses the soil nailing technique for slope stabilization. Soil nailing involves installing reinforcing bars called nails into the slope using drilling and grouting. The nails strengthen the slope by increasing shear resistance along potential slip planes and reducing driving forces. Key elements of a nailed structure include steel nails, centralizers, grout, nail heads, and facings. Construction involves excavating and drilling nail holes before installing and grouting nails. Soil nailing is used to stabilize slopes, excavations, and retaining walls, offering advantages like rapid construction and flexibility. Design considerations include nail spacing, inclination, length, and pattern. A case study describes using soil nailing to stabilize an embankment slope at a reservoir.

1. MAULANA AZAD NATIONAL INSTITUTE
OF TECHNOLOGY,BHOPAL
GEOTECTNICAL ENGINEERING
DEPARTMENT OF CIVIL ENGINEERING
2018-19
A
Presentation on
SLOPE STABILIZATION BY SOIL NAILING TECHNIQUE
Presented by
Bhanu Pratap Singh
M.Tech 1st yr
Scholar No. 182111119

2. CONTENTS
 INTRODUCTION
 SOIL NAIL BEHAVIOUR
 ELEMENTS OF SOIL NAIL STRUCTURE
 CONTRUCTION SEQUENCE
 TYPES OF NAIL
 FAVORABLE AND UNFAVORABLE SOIL CONDITIONS FOR SOIL NAIL
 APPLICATIONS
 DESIGN CONSIDERATION
 ADVANTAGES
 CASE STUDY
 CONCLUSION
 REFERENCES

3. • Soil nailing is an in-situ reinforcement
technique by passive bars which can
withstand tensile forces, shearing
forces and bending moments. This
technique is used for retaining walls
and for slope stabilization.
• Bars are closely spaced and
construction proceeds from the top
to bottom.
• Its behavior is typical of that of
composite materials and involves
essentially two interaction
mechanisms. The soil- reinforcement
friction and the normal earth
pressure on the reinforcement.
INTRODUCTION
Source: Soil Nail Walls Reference Manual: U.S. Department of Transportation Federal Highway Administration

4. • The function of soil nailing is to strengthen or stabilize the existing steep
slopes and excavations . Soil nails develops their reinforcing action through
soil-nail interaction due to the ground deformation which results in
development of tensile forces in soil nail.
• The effect of soil nailing is to improve the stability of slope or excavation
through;
1. Increasing the normal force on shear plane and hence increase the
shear resistance along slip plane in friction soil.
2. Reducing the driving force along slip plane
SOIL NAIL BEHAVIOUR
Source: International Journal of Engineering Science and Computing, December 2016

5. • Steel reinforcing bars
• Centralizers
• Grout
• Nail head
• Temporary and permanent facing
• Drainage system
EELEMENTS OF NAILED STRUCTURE
Source: Soil Nail Walls Reference Manual: U.S. Department of Transportation Federal Highway Administration

6. CONSTRUCTION SEQUENCE
Excavation
Drilling of Nail Holes
Nail Installation and Grouting
Installation of Strip Drains
Construction of Initial
Shotcrete Facing
Construction of Subsequent
Levels
Construction of Final Facing
Source: Soil Nail Walls Reference Manual: U.S. Department of Transportation Federal Highway Administration

7. CROSS-SECTION OF SOIL NAIL
Source: Soil Nail Walls Reference Manual: U.S. Department of Transportation Federal Highway Administration

8. NAILS
DRILLED and
GROUTED SOIL
NAIL
Dia. 100-200mm
DRIVEN SOIL
NAILS
Dia. 20-25mm
Faster installation
SELF DRILLING
SOIL NAILS
Drilling and
grouting in one
operation
JET GROUTED
NAILS
LAUNCHED
SOIL NAILS
Dia 25-38mm
TYPES OF SOIL NAIL

9. Favorable
• Dense to very dense granular soils
with apparent cohesion
• Stiff to hard fine-grained soils
• Engineered fill
• Residual soils
Unfavorable
• Dry, poorly graded cohesionless soils
• Granular soils with high groundwater
• Soils with cobbles and boulders
• Soft to very soft fine-grained soils
• Collapsible, Expansive and Organic soil
• Highly corrosive soil
Favorable/Unfavorable Soil Conditions for Soil Nailing

10. APPLICATIONS
• Stabilization of railway and highway cut slopes
• Repair and Reconstruction of Existing Retaining Structures
• Road Widening Under Existing Bridge Abutments
• Stabilizing steep cuttings
• Providing long term stability to existing concrete structures without
demolition and rebuild cost.
• Excavation of retaining structures in urban areas for high rise
buildings and underground facilities.

11. APPLICATIONS
Source: International Journal of Engineering Science and Computing, December 2016

12. Resisting Mechanisms
As we go deeper Volume of deformed soil expands and thus the forces in nail goes
on increasing.
Load shared by the upper nails is less as compared to what shared by the lower
nails
Source: Soil Nail Walls Reference Manual: U.S. Department of Transportation Federal Highway Administration

13. DESIGN CONSIDERATION
1. Vertical and Horizontal Spacing of Soil Nails
• Adopt SH = SV = 5 ft.
• Check: SH × SV ≤ 36 to 42 ft2
2. Vertical Spacing at the Top and Bottom of the Wall
• The spacing between the first row and the top of the wall (SV0) is selected as:
SV0 ≤ 3.5ft.
• The spacing between the deepest row and the bottom of the wall (SVN) is:
SVN ≤ 2 to 3 ft
3. Soil Nail Inclination
• between 10 to 20 degrees
4. Soil Nail Length
• L = 0.7 H ; generally in between 0.6H to 1.2H
5. Soil Nail Pattern
• either square or staggered pattern
6.Tendon for soil nail
• Solid Bar- Dia .86in. To 1.86in. ; Length- 60ft
• Hollow Bar- Dia. Outer: 1-3in , Dia inner: .3-1in, Length- 10-20ft
Continue…….

14. 7.Maximum tensile forces
• In upper two third
• In lower one third value reduces to 50% of above.
8. Tensile force at wall facing
9. Pullout Resistance
q = nominal bond strength of the nail-grout-soil interface (force/unit area)
D= diameter of the drill hole
L= pullout development length
10.Nail Tensile Resistance
A = cross-sectional area of nail tendon
F = nominal yield resistance of nail tendon
Tmax = 0.50 Ka γs H SV SH to Tmax = 1.1 Ka γs H SV SH.
To= Tmax[0.6+.057(Smax-3)])]
Rp = πqDL
Rt = Af

15. 10. Tmax = min
• Tensile Resistance of Nail
• Pull out resistance
• Facing Resistance
Source: Soil Nail Walls Reference Manual: U.S. Department of Transportation Federal Highway Administration

16. ADVANTAGES
CONSTRUCTION
• Requires smaller space
• Less disruptive to traffic
• Rapid and uses less construction material
• Advantages at sites with remote access
PERFORMANCE
• Performed well during seismic events
• Relatively flexible
COST
• Economical
• Shotcrete facing is less economical

17. CASE STUDY-Stabilization of Slope of Reservoir
• One of the earthen slope sections forming section of an impounding reservoir
failed at the interface of core and cover over about 200 m length and it was
indicated that the casing soil that was used initially in the construction was
cohesionless and prone to erosion and hence failure occurred.
• A better soil was used which had good silt and clay content and is less prone to
erosion, which also did not prevent failure along the interface.
Source: Case Studies in Soil Nailing 584IGC 2009, Guntur, INDIA

18. • It is also noted that a number of tension cracks exist along the length of the
embankment which could be detrimental to the stability of the other
sections as well. Hence to improve shear resistance along the interface,
soil nailing technique was used.
Table 1: Values of the Parameters Used in the Analysis
Material
Bulk density
(kN/m3 )
Cohesion
(kPa)
Friction angle
(degrees)
Hearting soil 17.8 30 14
Casing soil 20.3 10 20
Cohesion
(kPa)
Factor of
safety
10 1.62
5 1.22
3 1.06
2 0.98
Table2: Variation of Factor of Safety
with Cohesion of the Casing Soil
Source: Case Studies in Soil Nailing 584IGC 2009, Guntur, INDIA

19. • It may be noted that compacted soils such as the casing materials have
cohesion values due to capillary stresses which get reduced during the
rainy season.
• Loss of cohesion leads to overall reduction in shear resistance of the soil
leading to slope failure as in this case.
• In order to increase the available shear resistance, introduction of
reinforcement is useful. Hence tor steel (with yield strength of 415 MPa)
rods of 20 mm diameter and 5 m length, spaced at 0.5 m vertically and 1m
horizontally are suggested and the section is analyzed.
Source: Case Studies in Soil Nailing 584IGC 2009, Guntur, INDIA

20. • Soil nailing has great advantages, thus there is a need to use this
technique on large scale in India in many infrastructure projects wherever
applicable to realize the technical and economic advantages associated
with the technique.
• Soil nailing is being used in many geotechnical applications to improve
stability of excavated vertical cuts and existing slopes.
• The vertical cut stability/slope stability improved due to the reinforcing
effect of nails. The study illustrates that the technique is a viable
technique to improve the stability of vertical cuts and stability of existing
slopes and its advantages need to be exploited on a large scale in
infrastructure projects.
CONCLUSION

21. REFERENCES
• Soil Nail Walls Reference Manual, “AASHTO LRFD Bridge Design Specifications, 7th
Edition. “ , U.S. Department of Transportation Federal Highway Administration.
• Sivakumar Babu G.L., ”Professor, Department of Civil Engineering, Indian Institute of
Science, Bangalore “ , “Case Studies in Soil Nailing”, IGC 2009, Guntur, INDIA.
• Arora R.P,Associate Professer, CE, CTAE, Udaipur, India ‘’Soil Nailing for Slope
Stabilization’’ , International Journal of Engineering Science and Computing,
December 2016 .
• Dr. Purnanand P. Savoikar, Professor2Department of Civil Engineering, Goa Engineering
College, Farmagudi, Goa, “Study of soil nailing for highway retaining wall in Goa”,
Indian Geotechnical Conference IGC2016 15-17 December 2016, IIT Madras, Chennai,
India.
• Sivakumar Babu G.L, ”Professor, Department of Civil Engineering, Indian Institute of
Science, Bangalore Ground improvement, “Ground reinforcement using soil nailing”,
NPTEL Courses.