Soil Nailing Uses and Applications: New and Old

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Soil Nailing Uses and Applications New and Old

• Presented 11/05/09
• By Jeffrey M. Owad

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What is Soil Nailing?

• Slope stabilization System
• Earth Retaining System
• Soil Nails increasing the normal force and hence
  the soil shear resistance along potential slip
  surfaces in frictional soils and reducing the
  driving force along potential slip surfaces in
  both frictional and cohesive soils.- FHWA
  Report No. FHWA-IF-99-026

30ft Soil Nail Wall behind Home Depot in
Gladstone, MO
Source http//www.judycompany.com/engineer/articl
es/home-depot.htm
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Basic Soil Nailing Installation

• Soil Nailing is a Top-Down Construction
• The wall is built in layers or lifts as material
  is excavated
• When Used as an earth retaining structure, the
  wall is Faced with a layer of reinforced
  Shotcrete

Source FHWA Report No. FHWA-IF-99-026
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Soil Nails

• Soil nails vary in diameters of ¾ to 1 ½
• Nail can be made from standard deformed rebar,
  epoxy coated rebar, and threaded steel rod
• Nails are spaced both horizontally and vertically
  at set intervals based on the existing soil
  conditions
• range from as close together as 2 ft to as much
  as 10 ft with nail
• at a 10 to 20 degree incline below the horizontal
  to help ensure successful grouting

Source http//www.dsicanada.ca/products/geotechni
cal-business/dywidag-soil-nails/anchorage-system-a
nd-centralizers.html
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History of Soil Nailing

• Soil Nailing has been used for over 30 years now
• Very popular in Europe and Canada for over
• Rapidly gained more expectance in the United
  states over past two decades
• Developed as an extension of rock bolting and of
  the "New Austrian Tunneling Method" (NATM)
• Method combines reinforced shotcrete and
  rock-bolting to provide a flexible support system
  for the construction of underground excavations.
  
• Earliest reported works include
• use for retaining walls in France (1972)
• Rail way cut slope construction in Germany
  (1976).
• Temporary excavation support , British Columbia
  (Early 1970s)

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Design of Soil Nail Systems

• Estimate working nail forces and location of the
  potential sliding surface.
• Select the reinforcement type and verify that
  nail resistance is sufficient to withstand the
  estimated working forces with an acceptable
  factor of safety.
• Specify how stability of the nailed-soil will be
  maintained during and after excavation with an
  acceptable factor of safety.
• Estimate the system of forces acting on the
  facing and design the facing for specified
  architectural and durability criteria.
• For permanent structures, select corrosion
  protection relevant to site conditions.
• Select the drainage system for groundwater
  levels.

Source http//www.phigroup.co.uk/tags/soil-nailin
g/structure-b150-midland-expressway
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Laguna Regional San Diego, CA

• New School Backs up to CALTRANS R.O.W.
• Traditional installation not possible
• Sacrificial Soil Nail Wall installed
• 30 vertical cut, 1,200 long

Source www.geogridwalls.com/pdfs/lagunaregional.p
df
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City Creek Center- Block 76Salt Lake City, UT

• 10 Acre Site
• 1 Billion Dollar Downtown Development Project
• Over 120,000 Sq Ft of Soil Nail wall
• Strict One Inch Movement Criteria for the Earth
  Retaining Systems due to the adjacent builds. Up
  to 23 stories high

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Chinese Embassy BuildingWashington D.C.

• 1,600 Soil Nails and 50,00 Sq Ft of Wall used in
  Site Excavation
• Adjacent Embassies Would not Grant underground
  easements
• Design Challenges included
• Soft Soils
• Inside Corners of walls
• Underground Utilities
• Impact from blasting at the site

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Sculpted Soil Nail Walls

• Various D.O.T. around the Nation have made use of
  these walls
• Including California, Kentucky, and Iowa
• CALTRANS Reports Soil Nail half the cost of
  traditional tie-back system
• As Shotcrete is applied, a team of Sculptors
  follows and shapes the shotcrete to blend in with
  the Environment and simulate natural rock
  formation in area.
• Construction causes less impact on traffic than
  traditional methods- Less Lane closures

Source http//www.dot.ca.gov/newtech/dri_annual_a
ccomplishments/
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Pneumatic Soil Nail Launchers

• Differs from traditional Soil Nail Installation
• No grout required
• Reduced installation time
• Developed from British military technology that
  was originally built to distribute Nerve Gas
• Use include the emergency repair of road way
  slopes and embankments
• Can launch 1 ½ bars 20 ft into soil

Source http//www.ledger-dispatch.com/news/newsvi
ew.asp?c196901
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Summary

• Benefits
• Quick installation compared to traditional
  tie-back systems
• Minimal vibration/soil disturbance to surrounding
  sites
• Minimal R.O.W. or underground easement required
• Does not need to be built up to retain soil,
  maximizing land use of site
• Wall height is not restricted
• Can be finished to either blend in with natural
  rock formations in the area or covered with
  architecturally pleasing precast panels.
• More Economical than other earth retaining
  systems

• Uses
• Temporary Retaining Systems for Deep Excavations
• Permanent Retaining Walls
• Landslide and Slop Stabilization
• Supporting and strengthening soil around Tunnel
  excavation
• Temporary Shoring during the repair of existing
  Earth Retaining Structures
• Stabilization of vertical Cuts with limited Right
  of Way (R.O.W)

Source http//www.paragoneng.net/msewalldesign.ht
ml
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Questions??
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SourcesIn addition to those listed throughout
presentation

• Byrne, R.J., Cotton, D., Porterfield, J.,
  Wolschlag, C., and Ueblacker, G. Publication No.
  FHWA-SA-96-069R Manual for Design and
  Construction Monitoring of Soil Nail Walls.
  (1998) FHWA, Washington D.C. Posted
  Electronically by FHWA at http//isddc.dot.gov/OLP
  Files/FHWA/010571.pdf.
• Juran, I., and Elias, V. (1991). Ground anchors
  and soil nails in retaining structures. Chap. 26
  in Foundation engineering handbook, 2nd Ed., 
• Phear, A. and Johnson, J. Nail File-(2005) New
  Civil Engineer, http//www.nce.uk/nail-file/541448
  .article
•  
• Singla, Sumant . Report No. FHWA-IF-99-026
  DEMONSTRATION PROJECT 103 Design Construction
  Monitoring of Soil Nail Walls,(1999) FHWA-
  Office of Infrastructure, Washington D.C. Posted
  Electronically by Vulcanhammer.net at
  http//www.vulcanhammer.net/geotechnical/FHWA-IF-9
  9-026.pdf.
• Turner, J.P., and Jensen, W.G. Landslide
  stabilization Using Soil Nail and Mechanically
  Stabilized Earth Walls Case Study( Feb. 2005)
  Journal of Geotechnical and Geoenvironmental
  Engineer, ASCE, Pgs 141-150