soil nailing presentation -22

7/28/2019 Soil Nailing Presentation -22

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Haldia Institute of TechnologyCivil Engineering Department

Thursday, November22,2012


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Introduction

Soil nailing is a technique in which soil slopes,excavations or retaining walls are reinforced by theinsertion of relatively slender elements - normally

steel reinforcing bars.

Soil nailing isused mainly to

protect soil slopefailure

Thursday,November22,2012


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in 1972

1960's and earlier

Literature Review

in 1961

in the 1970's

"New Austrian Tunneling Method"(NATM), in which grouted rockbolts and shotcrete were used forsupporting tunnels

permanent support of retaining wallsin a cut in soft rock in France.

The use of grouted "soil nails" anddriven soil nails, which consist of solidsteel bars and steel angle iron,continued to grow in the 1970's, in

France, Germany and north America

The first wall built in Franceusing current soil nail techniqueswas reported to have been builtin Versailles

Thursda November22 2012


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Guidelines and Manuals

In the 1991

In 1993 (FHA)

In 1987 One of the first nationalguideline publications for soilnailing. ( In Japan)

in France (Clouterre Program)$ 5 million study to develop designmethodology for soil nail walls

Federal Highway Administration

published its "Manual for Designand Construction of Soil NailWalls.



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Slope Failure

What is slope failure ?-The slope can not support itself

- Gravitational and seepage forces cause

disturbing force

- If disturbing moment > resistingmoment Slope will failure



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Slope stabilization methods

Shotcrete

Soil Nailing

NaturalMasonry



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Soil uses

Soil nailing is used to reinforce-tunnels wall support-soil cut slopes

-retaining wall support-excavations,-disturbed terrain and-natural hillsides stabilize



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Principle of Soil nailing

Active Zone

Slip SurfacePassive Zone

- In slope stability calculations, the resultneeds to obviously ensure that the resistingforces are greater than the force tending to

cause slope failure.


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Factor of Safety ( FOS )

-FOS is defined as the ratio of totalresisting forces to total disturbing forces or

total overturning moment.

There arethree

types of

FOS



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Nails

Driven NailGrouted Nail


Launched nails

Jet-grouted nails

Corrosion-protected nails


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Components of soil nail

Nails Centralizer

Grout

Head



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Construction Sequence



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Advantages

Economic

redundancy

Construction

Adaptability

Flexibility


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Limitations

Unsuitable soil

Groundwater


Vibration sensitive

prolong downpours

Utilities


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Comparison with Ground Anchor Wall



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Soil nailing failure

Pullout failureResult of insufficient embedded length into theresistant zone

Resistant

zone



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Nail tendon failureResults from inadequate tensile strength of thenails to provide the resistant force to stabilizethe slope



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Face failureResults if relatively small and nominal shotcretethickness and reinforcement is adequate.



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Case Study (1)

Vertical Slope 18 m below the ground They used:- 8200 nails

- About 670 tone

-16m to 18m bars long



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Case Study (3)


India (NH-8) 2009

Location :

Gurgaon-Jaipur Highway

Total face area : 500 Sq.m.

Total Nails : 600Nails

Max. height : 6 m


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Conclusion

-Soil nail construction has been shown to be asimple technology and does not need complexmachines.-This method can provide a lower construction,

period, and can provide good stabilize for slopefailure.- Soil nailing has some advantages and somelimitation. So, proper investigation and design

should be taken.- soil nailing should be avoided in some cases



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Thank you


soil nailing presentation -22

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