Abstract

The landslide which occurred in an expressway constructing site was turned out to be a large scale landslide with around 2.8 million cubic meters by the results of the detailed research. The ground anchors constructed as the countermeasures against this large landslide were the largest scale anchors in Japan in both length and numbers. The most important technical subject of this longer anchor was that anchor load was decreased by friction loss between sheath and tendon in the free anchor length, and that deterrent effect of anchors might not be expected. To recognize directly the friction loss in free anchor length, we carried out the test which was performed by multi-cycle loading with strain gages on tendon. As the results, we confirmed that friction loss was larger than calculated by the general empirical formula. In real works, we confirmed effects that the friction loss in free anchor length was decreased by multi-cycle loading before fixing.