貯水池における混合粒径材料の堆積とその排除法

Abstract

貯水池における混合粒径材料の堆積過程に関して, 水理実験と数値解析を行い, 堆砂デルタにおける粒度の鉛直分布特性などを明らかにしている。また, バイパストンネルを用いて効果的に堆砂を排除するために, 流入土砂を貯水池末端に設けた副ダム上流域に一旦堆積させ, 出水後に貯水池の水を副ダムのゲートから上流側へ逆流させることにより, 堆砂を再度侵食させて排砂する方法について, 数値計算により検討している。

We propose a one-dimensional simulation method in order to predict a reservoir sedimentation which causes imbalance of sediment runoff and spoils the function of reservoir. The model can calculate the temporal variation in the longitudinal bedprofile and the grain size distributions in a surface layer and a lower layer in deposits.The simulation model is verified by the data obtained from a flume experiment.We have already proposed a reduction system for sedimentation which is composed of a by-pass tunnel and a sub-dam. In the system, the transported sediment is stored in upstream area of the sub-dam during a flood, and after the flood, the delta is eroded by the flow discharged from a gate equipped to the sub-dam and the sedimentis transported into the by-pass tunnel. We develop a new two-dimensional simulation model in which the bank erosion is taken into account, and apply this model to the delta erosion process.