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水路壁の摩耗や劣化に対して表面被覆工法が局所選択的に実施され，補修区間と未補修区間が間欠的に連なったパッチワーク状に補修された水路を想定し，粗度係数の低下が補修区間の設置パターンに応じて水位の低下やエネルギー損失に与える影響を水理模型実験および不等流解析により明らかにした。水路底や水路幅の凹凸による水路断面の変化をなくした一様な水路であれば，パッチワークのパターンによらず，粗度の切り替わり部でのエネルギーの局所損失は発生せず，通常の不等流解析によって，水面形を精度良く算出できる。補修工事の設計・施工においては，あらかじめ不等流解析を行って，水位低下に必要な補修区間の長さを求め，溢水箇所の下流側から劣化の激しい箇所を優先的に補修していくことで，効果的に溢水を防ぐ対策が可能となることを示した。Hydraulic model experiments and non-uniform flow analysis were conducted to clarify the influence of the decrease of roughness coefficient on the water surface profiles and energy loss according to the installation pattern of the repair section, assuming the intermittent repaired channel. Regardless of the length of repaired sections nor frequency of switching repaired / non-repaired sections, local loss of energy did not occur in the boundary of the both sections, and it was found that the water surface profiles can be calculated accurately by conventional non-uniform flow analysis. To avoid flooding, it is necessary to determine the total repair length required for water surface recovery by conducting a hydraulic analysis beforehand. In designing and constructing a repaired channel, it is effective to repair preferentially the part with severe deterioration from the downstream side of the overflow point. |
