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臨海施設の排水路を対象とした津波による内水氾濫解析

津波により複雑な排水路を逆流し陸域に溢水する現象のシミュレーション

高畠 知行^＊１・本田 隆英^＊１・織田 幸伸^＊１・伊藤 一教^＊１

臨海施設に津波が来襲した場合，津波の遡上を防潮壁などで防いでも，取放水路や雨水排水路を介して津波が陸域に溢水・浸入し（津波による内水氾濫），浸水被害や避難経路損失の危険性がある。本研究では，こうした津波による内水氾濫現象に着目し，支管路を含む複雑な水路においても，溢水解析が可能な一次元解析モデルを構築した。立坑接続部の圧力差と溢水時の水面の盛り上がりを考慮することで，一次元モデルを用いても，三次元モデルとほぼ同程度の精度で溢水量が再現できることを確認した。本モデルで得られた溢水解析の結果を用いて，陸上での氾濫解析を行えば臨海施設での津波による内水氾濫解析が少ない計算負荷で可能になる。また本モデルを用いることで，津波波形の違いによる溢水特性の検討や対策工の効果検討などを行えることを示した。

＊１ 技術センター 土木技術研究所 水域・環境研究室

Simulation of Inundation Disasters via Drainage Channels at Seaside Industrial Plant Induced by Tsunami

Simulation of Overflow Phenomena from Pits via Drainage Network Channels

Tomoyuki TAKABATAKE^*1, Takahide HONDA^*1, Yukinobu ODA^*1 and Kazunori ITO^*1

This paper studies about inundation disasters via drainage channels induced by tsunami, which may occur even if high seawalls protect inside areas from tsunami. Since the inundation may cause massive damage and lead to losses of evacuation routes, it is important to consider the countermeasures for industrial facilities from a view point of a business continuity. An 1-D pipe network flow model, which is generally used for a surging analysis, was improved to evaluate an amount of overflow from pits of a channel network. In the improved 1-D model, an elevation of water surface caused by overflow at a pit top and a pressure difference which occurs on the connections between a pit and pipes are taken into consideration. It was found that the improved 1-D model could reproduce the almost same results from a 3-D model simulation. By using the improved 1-D model, it became possible to evaluate the overflow phenomena induced by tsunami with less computational load. In addition, characteristics of overflow induced by tsunami and effects of countermeasures against that were examined with the improved 1-D model.