Transportation agencies use tensioned systems to solve geotechnical engineering problems. Metal tensioned systems include, but are not limited to, rock bolts, soil nails, and permanent ground anchors. These systems are anchored by various means, including mechanical systems, epoxy and polyester resins, and cement grout. The failure of a metal tensioned system can lead to loss of life, significant economic loss to the public, property damage, and large rehabilitation costs to transportation agencies. The key issue for this research is to identify or refine tools to predict the remaining useful life of existing installations and the design life of new installations of metal tensioned systems.
The objective of this research was to develop a recommended practice, suitable for adoption by AASHTO, for procedures to evaluate the condition and remaining useful life of in-place metal tensioned systems, and to estimate the design life of new installations. The practice should consider key factors such as the following: materials used in the tensioned systems, corrosion, anchorage methods, soil and rock conditions, environmental effects, construction techniques, long-term, cost-effective measuring techniques, and other critical factors.
The final report was published as NCHRP Report 477
. The recommended practice has been submitted to the AASHTO Highway Subcommittee on Materials for review and consideration for possible adoption. Several workshops titled "Screening, Evaluating and Managing the Aging Inventory of Buried Metal-Tensioned Systems Used in Geotechnical Applications" developed from the results of this project have been presented at regional geotechnical conferences. The workshop manual and PowerPoint module presentations are available for loan on request to NCHRP.
The Phase I interim report was published as NCHRP Web Document 27.