HIGHWAY TECHNET VIRTUAL EXPO STRUCTURES INDEX
DP-103 Soil Nail Walls
Nails That Bite the Dirt
The basic concept of soil nailing is to reinforce and
strengthen the existing ground by installing closely spaced
steel bars, called "nails," into a slope or excavation as
construction proceeds from the "top down." This process
creates a reinforced section that is itself stable and able to
retain the ground behind it. The reinforcements are passive
and develop their reinforcing action through nail-ground
interactions as the ground deforms both during and
following construction. Nails work predominantly in
tension, but are considered by some to also work in
bending/shear under certain circumstances. Generally, the
soil nails significantly increase the apparent cohesion of the
soil through their ability to carry tensile loads. A
construction facing is also usually required, and is typically
shotcrete reinforced by welded wire mesh. For
permanent walls, the shotcrete construction facing is
typically covered by a cast-in-place concrete facing.
The primary objective of this project is to demonstrate the cost-effective and technically correct application of soil nailing by the U.S. transportation community. The project is directed toward geotechnical, structural, and construction engineers who design and construct geotechnical facilities (embankments, cut slopes, retaining walls, and structures). The demonstration project has four major elements:
Project development included the following: a summary report for a 1992 European scanning tour titled FHWA Tour of Geotechnology Soil Nailing was prepared and distributed in early 1993. The French soil nailing manual, Recommendations Clouterre 1991, has been translated into English and was distributed in 1994. The FHWA Soil Nailing Field Inspector's Manual has been prepared and was also distributed by OTA in 1994. A testing program to determine ultimate structural capacities of soil nail wall shotcrete facings was conducted at UC San Diego and will be completed late in the summer of 1995. The facing test program included testing fullsize test panels to failure and analytical modeling, and was a cooperative program co-sponsored by FWHA, Caltrans, and Industry. A Manual for Design, Construction and Monitoring of Soil Nail Walls And a 2day training workshop were developed and are now available to State DOTs. The manual is "practitioner oriented" and includes step-by-step design procedures, hand calculation worked design examples, example plan details, and guide construction specifications. A proprietary computer design program, "Goldnail" is demonstrated during the workshop and is distributed to each State under a specific lisencing agreement with the program developer. Project-specific design and construction technical assistance, including field inspector training, is now available.
Technical assistance is being provided to several States during the project. A team of Federal Highway, State Highway, and private consultants also traveled to Europe to investigate soil nailing techniques. The results of their trip are incorporated into the project.
Soil Nailing Field Inspectors Manual
Manual for Design, Construction and Monitoring of Soil Nail Walls, FHWA-SA-96-069 is available from NTIS.
English translation of the French manual
"FHWA Tour for Geotechnology Soil Nailing"
HIGHWAYTECHNET VIRTUAL EXPO STRUCTURES INDEX
U.S. Department of Transportation
Federal Highway Administration