Debris Flow Controlled by Steel-Grid Sabo Dams According to Grain-Size Frequency

Abstract

Norio HARADA and Yoshifumi SATOFUKA 1 正会員 三井共同建設コンサルタント株式会社(〒552-0007 大阪市港区弁天1丁目2番1-1000号) 2 正会員 工博 立命館大学教授(〒525-8577 滋賀県草津市野路東1-1-1)Debris flow can be trapped in a steel-grid sabo dam, due to the blockade of coarse woody debris without large stones. In addition, the permeable width of the barricade is not determined by the grain-size accumulation rate, but rather by the grain-size frequency. Information on the grain-size distribution characteristics in mountain streams is needed before construction of the dam. In this study, to identify the ideal structure for controlling sediment runoff, we experimented with the structure of the dam to show how the capture rate is affected under different conditions. The capture effect was evaluated for several grain-size distributions of real mountain stream beds to determine the relationship between grain size and the capture rate.

Sediment Trap Function of Open-type Steel Sabo Dam with respect to Shape and Installation Slope

“…Based on the technical standard for designing sabo facilities against debris flow and debris wood [Ministry of Land, Infrastructure, Transport and Tourism, 2007], sticks were placed at 10 mm intervals, which approximately correspond to the maximum particle size, but the lowest horizontal bar was set 15 mm above the riverbed. In order to trap sediment effectively, the grid -type dam with vertical columns was placed on the upstream side [Harada and Satofuka, 2014].…”

“…They did not vary the gradient or examine the performance differences of the vertical-type and horizontal-type dams. There was a study focused on the different shapes of dams [Harada and Satofuka, 2014], but it was only for dams in waterways with a slope greater than 15 . Therefore, in this study, we collected information about actual open-type steel sabo dams and conducted channel experiments.…”