Method to evaluate the effect of inclination angle of steel open

Although the latest statistics indicate a decrease in the number of victims of natural disasters in Japan, the number of sediment disasters has increased. A countermeasure against natural disasters is provided by the installation of a steel open-type check dam (hereafter, open Sabo dam). The open Sabo dam is expected to capture boulders (more than 1.0？m in diameter) contained in debris flow of which boulders concentrate in front part. When a debris flow impacts an open Sabo dam, the large impact load on the steel pipes are caused by the impact of boulders under debris flow. Therefore, it is important to evaluate the impact of both boulders and the following soil and small gravels including fluid force of the open Sabo dam from the design point of view. Although an open Sabo dam has various shapes especially, the every open Sabo dams is evaluated by the same design method in Japan. It is necessary to propose the load evaluation method in the experiment scale in contrast with different shape of open Sabo dam. This article presents an experimental approach to determine the effect of the front inclination angle of steel open Sabo dams on the impact load. The debris flow impacts 1/40 scale models of steel open Sabo dams which are set in a flow channel flume, and the debris flow load is measured by using three load cells placed horizontally at the back of the Sabo dam model. Different front inclination angles are set for each Sabo dam models. The time history of the impact load is examined by comparing the loads corresponding to four kinds of dams, which are different from the front inclination angles, and decrease of impact load considering the buffering effect of driftwoods in debris flow