In-situ loading test of wooden pile at Shinano River Ohkouzu old movable weir and discussion on foundation design

Abstract

The old movable weir at Shinano River Ohkouzu in Nagaoka city was demolished owing to aging of structure, after construction of the new movable weir. This study reports the rapid loading test results of wooden piles installed below the foundation of movable weir and discusses the design method of foundation. Ground survey clearly illustrated the geological structure of the ground and indicated the wooden piles of 13m in length below the pillar was supported by the dense sandy layer. On the other hand, the wooden piles of 7m in length at the channel was shown to be supported by the thin dense sandy layer. Ultimate bearing capacity of wooden pile was estimated by the in-situ rapid loading test of piles. It matched with the design value in case of the channel, but it was smaller than that in case of the pillar. The foundation design of the pillar was found based on the piled raft foundation theory. Wooden piles had maintained the integrity of material, although it was constructed before about 80 years.