Drilled/Grouted and Hollow Bar Soil Nailing Cost Information
<p><p><h2>Commentary</h2>The costs of drilled/grouted soil nails on a highway project are typically captured in the following contract pay items:<br><ul> <li>Soil nails measured by the lineal foot (LF) or by each (EA) nail installed</li> <li>Drainage system by the square foot (SF)</li> <li>Permanent or temporary wall facing by the square foot (SF)</li> <li>Mobilization, quality control, and load testing associated with the installation of drilled/grouted soil nails may be measured and paid for separately.</
Drilled/Grouted and Hollow Bar Soil Nailing Fact Sheet
<p><p><figure id='attachment_2571' style='max-width:932px' class='caption aligncenter'><img class="wp-image-2571 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Cross-section diagram showing the typical layout of soil nails in a wall." width="932" height="553" /><figcaption class='caption-text'> Typical Cross Section of Soil Nai
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Drilled/Grouted and Hollow Bar Soil Nailing Specifications
Summary of Example Specifications
Summary of Example Specifications
Specification Name/Number: DFI Soil Nailing Guide Specification
Reference(s):
DFI (2009)
This specification can be modified to serve as a performance approach, method approach, or combination specification. In addition, a hollow bar soil nail supplement is provided. The specification is easy to read, logically ordered, and provides clear instructions for completing the work. There are no conflicting statements in the specification. However, the specification does not state what design method to use. This is left up to the contractor, which will make comparing bids difficult for the owner.
Overall performance requirements are not provided in this specification. The specification, as presented, is intended to take advantage of the contractor’s experience so that a large amount of responsibility lies with the contractor. The specification does not require overly elaborate or expensive construction methods. This specification clearly outlines the nail testing procedures and provides construction method requirements (combined performance/method specification). The specification also provides good commentary about how and why the QC/QA methods are required. This specification contains the sections required for a combined method/performance specification. ASTM material standards are clearly outlined. However, the specification does not state what design method to use or what are the required factors of safety.
Specification Name/Number: FHWA Procedural Specifications for Soil Nail Walls
Reference(s):
Lazarte et al. (2003)
The specification contains helpful commentary. This specification expressly forbids the use of hollow bar soil nails. The specification is easy to read, logically ordered, and provides clear instructions for completing the work. There are no conflicting statements in the specification. The specification fairly allocates the risk between the contractor and owner. The specification does not provide information about the subsoil conditions, shotcrete facing, or wall instrumentation. However, supplemental specifications for shotcrete facing and instrumentation are provided in Lazarte et al. (2003). The specification does not require overly elaborate or expensive construction methods. This specification outlines typical method and performance verifications for soil nailing. This specification alone is lacking certain sections (subsurface conditions, instrumentation, design methodology). However, it is intended to be used in conjunction with other guide specifications in the FHWA documents (shotcrete and instrumentation specification).
Specification Name/Number: FHWA Performance Specifications for Soil Nail Walls
Reference(s):
Lazarte et al. (2003)
The specification contains helpful commentary. The specification is easy to read, logically ordered, and provides clear instructions for completing the work. There are no conflicting statements in the specification. The risk is fairly allocated between the owner and contractor. The contractor is responsible for producing a design that is then constructed to satisfy specification requirements. The specification does not provide information about the subsoil conditions, shotcrete facing, or wall instrumentation. However, supplemental specifications for shotcrete facing and instrumentation are provided in Lazarte et al. (2003). The specifications do not require overly elaborate or expensive construction methods. This specification refers the reader back to the FHWA Procedural Specifications for Soil Nail Walls with some changes to allow more freedom of contractor methods. The specification therefore contains the same performance QC/QA as the FHWA Procedural Specifications for Soil Nail Walls. This specification contains the necessary modifications to the Procedural Specifications to create a pure performance-based specification.
Hollow Bar Soil Nailing
Current FHWA Reference: Lazarte et al. (2003)Reference(s):
Gomez (2009)
Rogbeck et al. (2003)
Samtani and Nowatzki (2006)
Material, Excavation, and Installation Inspection
<p><p><strong>Reference(s):</strong></p><p><em>Byrne et al. (1998)<br>Lazarte et al. (2015)<br>Porterfield et al. (1994)<br>Rogbeck et al. (2003)<br>SHRP2 Phase I Technology Assessment (2008)</em></p><p><strong>Method Summary</strong></p><p>Material, excavation, and installation inspection is the umbrella activity that includes nail inventory, inspection and oversight of construction procedures.
Proof and Verification Testing
<p><p><strong>Reference(s):</strong></p><p><em>Byrne et al. (1998)<br>Gomez (2009)<br>Lazarte et al. (2015)<br>Porterfield et al. (1994)<br>Rogbeck et al. (2003)<br>Samtani and Nowatzki (2006)<br>Terzaghi et al. (1996)</em></p><p><strong>Method Summary</strong></p><p>This method tests the strength of an individual soil nail by applying a specific load to a nail and measuring deflections and strain of the nail.
River Road Widening and Realigning, Pima County, Arizona
<p><p><figure id='attachment_3418' style='max-width:630px' class='caption aligncenter'><img class="wp-image-3418 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Arial view of the completed soil nail wall, River Road Widening and Realigning, Pima County, Arizona." width="630" height="463" /><figcaption class='caption-text'> Arial
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Specific Gravity Test
<p><p><strong>Reference(s):</strong></p><p><em>Byrne et al. (1998)<br>Gomez (2009)<br>Lazarte et al. (2015)</em></p><p><strong>Method Summary</strong></p><p>The specific gravity test is conducted on grout prior to and during grouting as a quality control measure and is used to confirm the water content (i.e., water-cement ratio) of the grout.
Surveying
<p><p><strong>Reference(s):</strong></p><p><em>Byrne et al. (1998)<br>Lazarte et al. (2015)<br>Porterfield et al. (1994)<br>Rogbeck et al. (2003)<br>SHRP2 Phase I Technology Assessment (2008)</em></p><p><strong>Method Summary</strong></p><p>Deflections in the wall can be accurately measured over the length of the wall with surveying equipment. The site should be surveyed on a specified regular schedule in order to monitor and record any wall movements.
Tension Test
<p><p><strong>Reference(s):</strong></p><p><em>Rogbeck et al. (2003)</em></p><p><strong>Method Summary</strong></p><p>The test is conducted in a laboratory. A soil nail is loaded in tension to determine strength. Opposing outward loads are applied using testing machines. The nail is loaded until failure or yielding.
U.S. Highway 26-89 Landslide Stabilization, Wyoming
<p><p><figure id='attachment_3420' style='max-width:554px' class='caption aligncenter'><img class="wp-image-3420 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Cross-section diagram showing layout of soil nails to stabilize a landslide along U.S.
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Visual Inspection
<p><p><strong>Reference(s):</strong></p><p><em>Byrne et al. (1998)<br>Lazarte et al. (2015)<br>Porterfield et al. (1994)<br>Rogbeck et al. (2003)<br>Samtani and Nowatzki (2006)</em></p><p><strong>Method Summary</strong></p><p>Visual inspection of the excavated ground materials ensures that the soil characteristics were correctly determined during preliminary testing.