Yukinobu Oda

BEHAVIOR OF THE 2011 TOHOKU EARTHQUAKE TSUNAMI AND RESULTANT DAMAGE IN TOKYO BAY

The behavior of the 2011 Tohoku earthquake tsunami in Tokyo Bay and its resultant damage to the coasts are studied using a field survey, an analysis of observed tsunami wave profiles and numerical hindcasting using FVCOM and Delft3D-Flow. The field survey reveals that the tsunami caused several fishery ports to overflow, and unexpectedly large inundation and run-up heights of 2.84 m and 2.91 m were recorded in Funabashi Fishery Port and Shin-Futtsu Fishery Port, respectively. Examining the observed tsunami wave profiles, the tsunami wave entered the bay with a maximum height of approximately 0.9 m for the second wave and a period of approximately 60 min, propagating along the major axis of the bay with almost uniform height. Numerical hindcasting results using both the models are fairly consistent with the measurements, revealing that the tsunami wave heights are locally amplified in ports because of wave reflection, water accumulation due to their narrow and enclosed shape, and, to some extent, the harbor resonance. Heavy damage to seaweed farming was also observed, especially around the Futtsu Cape and the northern part of the Banzu tidal flat, which numerical analysis attributes to the appearance of large hydraulic resistance on seaweed net.

An Experimental Study on Resistance of Coastal Dike with Lean Cement Mixed Soil

The tsunami generated by the 2011 off the pacific coast of tohoku earthquake caused massive damage to coastal dikes. It is required for coastal dikes to increase the resistance of tsunami. Although some coastal dikes resistant to tsunami are proposed, embankment materials which can enhance the resistance of coastal dikes are not identified clearly. In this study, embankment materials of a coastal dike which can enhance its resistance are investigated by conducting hydraulic physical model tests. The results of hydraulic tests showed that embankment mixed by cement or clay could enhance the resistance of tsunami. The numerical simulation was also conducted to clarify the erosion process of lean cement mixed soil.

Physical Model Test of Tsunami Wave Force on a Refuge Facility Protected with Fender Piles

本論で対象とした津波避難ビルは,津波漂流物の衝突 防止および津波が引いた後,漂流してきた自動車や船舶 が火災を起こした際にその火災の避難ビルへの延焼を防 ぐために,全周に杭式防衝工を配置した構造形式である. ここでは,防衝工が津波来襲時の避難者に与える影響に ついて考察する. 防衝工の存在が避難者に威圧感や抵抗感を与える可能 性を考え,防衝工の配置として図-1(a)の直線配置と避 難性の向上をねらった(b)千鳥配置を検討対象とした. 防衝工は一辺1mの正方形の杭とした.津波避難ビルの 緒元は,縮尺1/62.5で記載した後出の図-6(a)(b)を参照 されたい.避難者が正面から見た防衝工の見え方を図-1 (c)(d)に示す.直線配置と千鳥配置ともに中央部には 開口を感じることができるものの両サイドは防衝工が互 いに重なりあい開口を感じることができない.しかし, 漂流物対策として防衝工を配置した津波避難ビルに作用する 津波波力に関する水理実験 Physical Model Test of Tsunami Wave Force on a Refuge Facility Protected with Fender Piles

Construction Techniques for Deep-water Immersed Tunnel Using Real-time Sea Strait Current Forecast

The Marmaray Project (Lykke and Belkaya 2005) in Istanbul, which provides an upgraded urban railway system approximately 76 km long with a 13.4 km underground section (see Fig. 1), is under construction to overcome Istanbul’s chronic traffic congestion. Istanbul is divided into a European side and an Asian side by the Bosphorus Strait, thus the new railway system needs to cross the strait. An immersed tunnel method was applied for the construction of the tunnel, called Bosphorus Crossing Immersed Tunnel, and it is at the present time the world’s deepest immersed tube tunnel. The tunnel elements were prefabricated off-site and towed by ship to the work-site for installation and connection to the previously installed underwater elements. The remaining parts on the Asian side and the European side are being constructed using TBMs (tunnel boring machines) and are to be connected to both ends of the immersed tunnel, which consists of 11 individual submarine elements each approximately 135 m long, 15.3 m wide and 8.6 m tall. The total length of the immersed tunnel is 1,387 m and the maximum depth of the bottom of the tunnel is 60 m under the water of the Bosphorus Strait.

REAL-TIME CURRENT FORECAST FOR TUNNEL IMMERSION WORK OF BOSPHORUS RAIL TUBE CROSSING PROJECT, TURKEY

Yukinobu Oda, Technology Center, Taisei Co., od-ykn00@pub.taisei.co.jp Takahide Honda, Technology Center, Taisei Co., hndtkh01@pub.taisei.co.jp Kazunori Ito, Technology Center, Taisei Co., kazunori.ito@sakura.taisei.co.jp Seizo Ueno, Technology Center, Taisei Co., seizo.ueno@sakura.taisei.co.jp Fumio Koyama, International Operations Headquarters, Taisei Co., f-koyama@ce.taisei.co.jp Hideki Sakaeda, Pacific Consultants International, sakaedah@pcitokyo.co.jp Claus Iversen, Avrasyaconsult, civersen@avrasyaconsult.com Steen Likke, Avrasyaconsult, slykke@avrasyaconsult.com

3D HYDRODYNAMIC SIMULATION FOR THE WORK OF RAILWAY BOSPHORUS TUBE CROSSING

The immersed tunnel crossing the Bosphorus Strait located in Istanbul, Turkey, is under construction. It is known that the current field of the Bosphorus Strait is complicated. It has two-layer flow of surface southward and bottom northward. In this paper, the numerical hydrodynamic simulation, which is carried out to clarify the current structure, is described. This simulation results are used for construction assistance system. For the simulation, the salinity and temperature boundary conditions of both northern and southern ends of the strait are vertically given as step function. The simulation results agree with monitoring results well. Through the simulation, following results are found out. Large water level difference between both ends of the strait causes the increase of the current speed of both surface and bottom layers. However, in one range of the water level difference, the maximum current speed of the surface layer reaches a constant value of 1.8 m/s approximately. The current structure is mainly ruled by the shape of the density interface.