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Federal Highway Administration > Publications > Focus > June 2008 > FHWA Offers Soil Nail Showcase
June 2008Publication Number: FHWA-HRT-08-014

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FHWA Offers Soil Nail Showcase

For State transportation departments that have never built a soil nail wall or would like a refresher course on constructing one, the Federal Highway Administration’s (FHWA) Resource Center now offers a free Soil Nail Showcase. The showcase features a 2-day workshop, with the first day covering soil nail wall design and the second day highlighting soil nail wall construction inspection and soil nail testing. Also provided as part of the showcase is technical assistance, including review and comment on soil nail wall designs, contract plans, and specifications and onsite guidance on inspecting soil nail wall construction, testing soil nail loads, and preparing construction and testing documentation.

With the use of soil nailing, the existing ground is reinforced and strengthened by installing closely-spaced steel bars, known as “nails,” into a slope or excavation as construction of a retaining wall proceeds from the top down. This creates a reinforced section that is stable and able to retain the ground behind it. “Soil nails are a technology that could be used by virtually any State department of transportation, particularly to widen roadways underneath existing bridges without having to take the bridge out of service,” says Barry Siel of the FHWA Resource Center.

“Soil nails are a technology that could be used by virtually any State department of transportation, particularly to widen roadways underneath existing bridges without having to take the bridge out of service.”

The Soil Nail workshop can be scheduled as either two stand-alone 1-day workshops or a full 2-day workshop. The first day is targeted at geotechnical and structural engineers and covers the basics of designing and constructing soil nail walls. Topics covered include site investigation and sample testing, simplified design charts, and other design considerations. Use of a computer program, GoldNail, is also demonstrated. The workshop’s second day highlights construction inspection and is designed for construction engineers and inspectors. An overview session first covers the basics of soil nail wall design and construction. The workshop then looks at contract documents, quality control, construction monitoring and documentation, soil nail testing, and construction problem solving.

Figure 4. Photo. A soil nail wall is constructed to widen a roadway underneath an existing bridge near Olympia, WA. The soil nail wall is to the right of the existing bridge.
A soil nail wall is constructed to widen a roadway underneath an existing bridge near Olympia,WA.

 

Figure 5. Photo. A worker performs load testing on a soil nail in Salt Lake City, Utah.
Load testing is performed on a soil nail in Salt Lake City, UT.

Workshops have been held to date in Arizona, Missouri, and Nebraska, attracting a total of approximately 200 design and construction personnel. “The workshops have resulted in better understanding of soil nail wall technology. The feedback from participants has been very positive,” says Siel.

The technical assistance on construction inspection is designed as a follow-up to the Soil Nail workshop but can be requested regardless of whether a State has hosted the workshop. An FHWA technical expert in soil nail design and construction will visit a State transportation department’s soil nail wall construction site and work hands-on with State personnel to perform field quality control of materials, inspect soil nail wall construction, monitor soil nail testing, and complete construction documentation.

To schedule the Soil Nail workshop or to request technical assistance, contact Barry Siel at the FHWA Resource Center, 720-963-3208 (email: barry.siel@fhwa.dot.gov).

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Updated: 04/07/2011

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