1. Special Topics In Geotechnical Engineer
Soil Nailing
Special Topics In Geotechnical Engineer
Done By: Ali Feras Maadi
Student#:
Civil Engineering

2. CONTENT INTRODUCTION ORIGIN AND DEVELOPMENT
FAVOURABLE UNDER-GROUND CONDITIONS
TYPES OF GROUNDS SUITABLE FOR SOIL NAILING
COMPONENTS OF A SOIL NAIL WALL
TYPES OF NAILS USED
DESIGN REQUIREMENTS
MACHINERIES USED
MATERIALS USED
CONSTRUCTION SEQUENCES
APPLICATIONS
ADVANTAGES
CONCLUSION
REFRENCES

3. INTRODUCTION
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.
It is an effective and economical method of constructing retaining wall for excavation support, support of hill cuts, bridge abutments and highways.

4. ORIGIN AND DEVELOPEMENT
It evolved from the New Austrian Tunneling method which is a system for underground excavations in rock in 1960
The first application of soil nailing was implemented in 1972 for a railroad widening project near Versailles, France. A 18m (59ft) high wall was to be soil nailed
Germany and USA first used soil nailing in 1975 and 1976 respectively
In India use of soil nailing technology is gradually increasing and guidelines have been made by IRC with the help of Indian Institute of Science, Bangalore.

5. FAVOURABLE UNDER-GROUND CONDITIONS
The excavated soil should be able to stand unsupported in 1m-2m high vertical cut for maximum 2 days
Soil nails should be located above the ground –water table
The ground conditions should allow drill holes to be advanced without using drill casings

6. TYPES OF GROUND SUITABLE FOR SOIL NAILING
Stiff to Hard Fine-Grained Soils: Includes hard clays, silt clays and sandy silts. Have SPT value(N) around 9blows/300mm. Fine-grained soils possess low plasticity i.e. P.I. <15
Dense to Very Dense Granular Soils: Includes sand and gravel with SPT values > 30 and fines about 10 to 15 percent
Weathered rock with no Weakness Planes: May provide a suitable supporting materials for soil nails until there are no weakness planes i.e. planes dipping into the excavation
Glacial Soils: Glacial outwash materials are suitable for soil nailing as they are dense, well graded materials

7. COMPONENTS OF A SOIL NAIL WALL
Nail Bars: Steel reinforcing bars of nominal tensile strength of 420 Mpa (Grade 60) and 520 Mpa (Grade 75) are used.
Nail Head: Two main parts: A) bearing plate, hex nut and washers; B) the headed-stud.
Grout: A neat cement grout is used. Sand-cement grout can also be used. Water/cement ratio for grout ranges from 0.4 to 0.5
Centralizers: Made of polyvinyl chloride (PVC).It ensures that a minimum thickness of grout completely covers the nail bar.

8. Typical PVC centralizer
Grout is being placed with the help of pipes
Main components of a Soil Nail wall
Typical PVC centralizer

9. TYPES OF NAILS USED
Drilled and Grouted Soil Nail: Approximately mm in diameter. Spaced at about 1.5m apart.
Driven Soil Nails: Relatively small in diameter about 19 to 25mm.Spaced at approx 1 to 1.2m apart. Mechanically driven. Allows faster installation
Self Drilling Soil Nails: Consist of hollow bars which can be drilled and grouted in one operation. Allows faster installation than drilled grouted nails and provides corrosion protection
Jet-Grouted Soil Nails: First step, allows advancement of the nail to the final location. In second step, the bars are installed using vibro-percussion drilling methods
Launched Soil Nails: Bare bars are launched into the soil using a firing mechanism. Bars are 19 to 25mm in diameter and 8m in length.

10. DESIGN REQUIREMENTS
After a preliminary analysis of the site, initial designs of the soil nail wall can be begin.
This begins with a selection of limit states and design approaches.
The two most common limit states used in soil nail wall design is strength limit and service limit states.

11. LIMIT STATES
The strength limit state is the limit state that addresses potential failure mechanisms or collapse states of the soil nail wall system.
The service limit state is the limit state that addresses loss of service function resulting from excessive wall deformation and is defined by restrictions in stress, deformation and facing crack width under regular service conditions.
Modes of failure

12. MACHINERIES USED Drilling Equipments Grout Mixing Equipments
Shotcreting/ Guniting Equipments
Compressor

13. Grout Mixing Instrument Typical drilling equipment
Shotcreting is done using a pipe

14. Materials Used For Soil Nailing
Steel Reinforcements
Grout Mix
Shotcrete/Gunite
Grouted Reinforcements bars
Grout Mix

15. CONSTRUCTION SEQUENCES
Excavation
Drilling nail holes
Installation and grouting nails
Construction of temporary shotcrete facing
Construction of subsequent levels; and
Construction of a final, permanent facing

16. Initial excavation lift and nail installation
Typical drilling of soil nails with
Rotary Method

17. APPLICATIONS Stabilization of railroad and highway cut slopes
Excavating retaining structures in urban areas for high-rise building and underground facilities
Tunnel portals in steep and unstable stratified slopes
Construction and retrofitting of bridge abutments
Stabilizing steep cuttings
Stabilizing of existing over-steep embankments
Providing long term stability to existing concrete structures without demolition and rebuild costs

18. ADVANTAGES CONSTRUCTION: Requires smaller space as they are shorter
Less disruptive to traffic
Rapid and uses less construction materials
Advantageous at sites with remote access
PERFORMANCE:
Relatively flexible
Total deflections are within tolerable limits
Performed well during seismic events
COST:
Economical
Shotcrete facing is less costly

19. DISADVANTAGES
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.

20. CONCLUSION
Soil nailing is an accepted technology, the theoretical aspects of which 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.

21. Refrences
1. John P Turner et al, Lanslide Stabilization Using Soil Nail and Mechanically Stabilized Earth Walls, Journal of Geotechnical and Geo-environmental Engineering, Vol:131, No:2, 2005,
2. I H Wong et al, Field Performance of Nailed Soil Wall In
Residual Soil, Journal of Performance of Constructed Facilities,Vol:11, No:3, 1997,
3. Xinhua Xue et al, Application of Modified Gooodman Model In Soil Nailing , International Journal of Geomechanics,Vol:13, No:1, 2013,

22. THANK YOU……!!