Non-Destructive Evaluation of Installed Soil Nails

Recent forensic studies that investigated the failure of several Texas Department of Transportation (TxDOT) soil nailed retaining walls revealed that incomplete grouting of soil nails was a very common problem. This finding has raised serious questions about the adequacy of QC/QA procedures currently used by TxDOT for verifying the integrity of installed soil nails. The research study described in this report attempted to address these concerns by: (a) developing of a nondestructive test method to check the integrity of soil nails, and (b) identifying the construction variables that have the most dominant influence on grout integrity and developing guidelines to control them. The Sonic Echo method was selected, further refined and “customized” for nondestructive evaluation of soil nail grout columns. The optimum test parameter combination to be used with Sonic Echo testing was determined through several cycles of nondestructive testing that were conducted at an experimental soil wall that was specially built for this research. Among the various construction variables examined, grout rheology (or flowability) and tremie insertion length were found to be the most important parameters that influence the integrity of soil nail grout columns. A new grout consistency requirement is proposed based on the findings from this research.


  • English

Media Info

  • Media Type: Web
  • Edition: Technical Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 262p

Subject/Index Terms

Filing Info

  • Accession Number: 01099023
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/TX-07-0-4484-1, Report No. 0-4484-1
  • Contract Numbers: Project 0-4484
  • Created Date: May 13 2008 4:05PM