In ground anchors employed to prevent landslides, grout injected into and filling the free anchor length result in the peripheral surface also adhering to the ground. On this account, a structure is realized whereby the frictional resistance of the peripheral surface is expressed along the entire length of the anchor. The frictional resistance of the peripheral surface in the free anchor length is not considered in the process of anchor design, but research has shown that the proportion borne by this frictional resistance is relatively large. For this reason, when the anchor is under tension, it is thought that upward stress is transmitted to the ground via frictional resistance in the peripheral surface of the free anchor length. This interferes with the downward stress of the reaction plate-in other words the clamping force-and it has been pointed out that there is a possibility that the clamping effect, which is one of the effects that the anchor suppresses landslides, is thereby diminished. This research used full-scale anchor experiments, experiments with models, and numerical experiments to compare the in-ground stress accompanying tension in two anchor types (one with frictional resistance along the peripheral surface of the free anchor length and one without) . The findings for the anchor with frictional resistance along the peripheral surface of the free anchor length indicated that the clamping force was reduced and transmitted relatively deeper. From this fact, frictional resistance along the peripheral surface of the free anchor length is presumed to be a factor that hinders transmission of the clamping force.

View full abstract

The anchor works are often used against slope failures and landslides. All tension power of the planned anchors should be surely reached to the immovable layer grounds to fix moving blocks of landslides. Therefore, it is necessary to secure the enough length from the slip surface to the head of the anchor root. In this study, we examined how to set up the needed length of the anchor in the immovable layer ground in consideration of various types or construction techniques of the anchors.

View full abstract

In this research, pulling test of anchor piles had been carried out in fields and the indoor. By analyzing test results, effective length and limit plastic displacement of piles are obtained. By using these results, evaluation method for degree of soundness of piles is proposed by examining limit plastic displacement rate for effective length of piles. In addition, it is pointed out that anchor forces don't transmit effectively to the anchorage zone if free length of piles is so long, and it is important that pile test must be carried out within a design load because significant plastic displacements is caused for more loads.

View full abstract