Rikuma Shijo

Tsunami Simulation by 3D Model Around a Power Station Due to the 2011 Tohoku Earthquake

In the 2011 Tohoku Earthquake, many structures were destroyed by the tsunami whose magnitudes were much larger than the design level. Tsunami defense structures in coastal areas will need reinforcement in the future, and for that reason it is important to evaluate tsunami behavior and resulting tsunami force. This study analyzes tsunami transformation around a Haramachi thermal power station which suffered serious damage by the tsunami due to the 2011 Tohoku Earthquake and which has complex topography and building layout. A three-dimensional (3D) tsunami simulation is carried out for a surrounding region of the Haramachi thermal power station using boundary conditions of the water surface elevation and flow velocity obtained from a two-dimensional (2D) tsunami simulation by a nonlinear shallow water model. Using these boundary conditions, the computer fluid dynamic model FLUENT is employed to simulate the tsunami behavior around the Haramachi thermal power station. The validity of the predictions is examined by comparison with actual traces of tsunami inundation depths (I.D.).

Influence of wave shapes to Tsunami Wave Force Acting on a Bridge Superstructure

In the Tohoku-Pacific Ocean Earthquake, many bridges were washed away by the tsunami. In the future, countermeasure for tsunami disaster will be needed, and the evaluation of tsunami wave force acting on bridges will be very important. This paper discusses the hydrodynamic tsunami-induced force acting on a bridge superstructure based on hydraulic model experiments. The results showed that tsunami wave forces were different according to the shape of tsunami incident wave and it was confirmed that maximum wave forces could be expressed by a function of the wave front slope of tsunami incident wave.

Numerical Analysis Study on Tsunami Wave Force Acting on a Bridge Superstructure using VOF Method

ここで,u:流速ベクトル,p:圧力,μ:流体の粘性係 数,g:重力加速度ベクトル,ρ1:水の密度,ρ 2:空気 の密度,φ:水の充填率(0≦φ≦1),ρ:水と空気の混 在を考慮した見かけの密度である.式(1)と式(2)の 空間離散化には有限体積法を用い,流速と圧力の連成解 法にはPISO法を採用した.解析には汎用流体解析コード であるANSYS社のFLUENTを用いた. (2)再現する水理実験条件 数値解析で再現する水理実験で用いた水路は,図-1で 示す長さ20m,断面幅0.7m,断面高さ1.0mの片面ガラス 張りの可視化水路である.津波は図中左端のスライド式 造波板により生成し,造波板の稼働距離と速度,静水深 を調整することで,津波高と流速を変化させた.模型は, 図-2で示す縮尺1/50の部分模型を製作し,幅員11.64mの 箱桁橋上部構造に最大10m(実験で20cm)高さの孤立波 性状の津波が作用する状況を模擬した実験を行った(林 橋梁上部構造に作用する津波波力のVOF法による数値解析的検討 Numerical Analysis Study on Tsunami Wave Force Acting on a Bridge Superstructure using VOF Method