A STUDY ON TENSILE FORCE MANAGEMENT METHOD FOR ADDITIONAL GROUND ANCHOR CONSTRUCTION IMPLEMENTED AS A DETERIORATION COUNTERMEASURE

The anticorrosion functions of ground anchors (hereinafter anchors) have been strengthened after the revision of standards by the former Japanese Society of Soil Mechanics and Foundation Engineering (present Japanese Geotechnical Society) in 1988. However, some old-type anchors constructed before the revision have failed to achieve the prescribed function due to corrosion of steel materials. Therefore, the three NEXCO companies have indicated in their expressway policy that they will install a new type of anchor in the specific renewal and other works, which were approved in 2016. In installing additional anchors as a measure to supplement existing old anchors, some issues remain. For example, there is no concrete method developed to manage the tensile force when unloading tensile force of existing anchors. This paper examines the handling of existing anchors at the sites where special anchor renewal works were carried out and, based on the findings, proposes a tensile force management method to be used in countermeasures for anchor deterioration.