Taro Arikawa - Academia.edu (original) (raw)

Papers by Taro Arikawa

Research paper thumbnail of The Examination of Collision Speed Reduction Effect of Tsunami Debris at the Tip of Runup Wave by Reflected Wave

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2020

Research paper thumbnail of Experimental Study on Local Scour at the Base of a Monopile Offshore Wind Generator

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2020

Research paper thumbnail of Protective Performance of Movable Breakwaters Against Storm Surge and Tsunami

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2019

Research paper thumbnail of Experimental Study for Wave Pressure of the Covering State of Wave-Dissipating Blocks

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2009

Research paper thumbnail of 大規模水理模型実験による津波・高波に対する直立浮上式防波堤の水理特性に関する研究

PROCEEDINGS OF CIVIL ENGINEERING IN THE OCEAN, 2007

Research paper thumbnail of 防波堤の腹付け被覆ブロックの安定性

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2014

One of the possible basic structural countermeasures taken for a breakwater to protect foundation... more One of the possible basic structural countermeasures taken for a breakwater to protect foundation mound and seabed against scouring caused by overflow is widening work for increasing the height of the foundation mound behind the breakwater. The widening work behind the caissons is topped with scour prevention work and a revetment to provide scour resistance to the structure. But the stability of armour blocks on the widening works is not cleared. In this report, the physical experiments were conducted to make clear the mechanism of failure of armour blocks under overflow of tsunami, and to consider the estimation methodology of stability of armour blocks. The results indicated that the stability of blocks related with the porosity of blocks and was estimated by using Isbash equations.

Research paper thumbnail of 避難途中に津波によって溺れる危険性の検討

PROCEEDINGS OF CIVIL ENGINEERING IN THE OCEAN, 2008

Kimihiko ENDOU and Taro ARIKAWA The primary objective of tsunami disaster mitigation is to reduce... more Kimihiko ENDOU and Taro ARIKAWA The primary objective of tsunami disaster mitigation is to reduce the casualties. The major cause of the deaths is drowning by tsunami current, especially during evacuation. In the paper, the causes of deaths are discussed through reference to past experiences. A fault tree is presented to summarize the physical danger posed by tsunami waves to the human body, and the personal danger is discussed based on the tree. The stability of the human body against wave front collision and tsunami currents is discussed and threshold conditions are proposed. The time for evacuation is usually very limited and the risk of encountering a tsunami during evacuation is often high. Walking in inundated areas during a tsunami attack is especially dangerous. Vertical evacuation is highly recommended.

Research paper thumbnail of Consideration to the resiliency of protective structures against tsunami by using High Performance Computer

Japan Geoscience Union, 2014

The Committee for Technical Investigation on Countermeasures for Earthquakes and Tsunami Based on... more The Committee for Technical Investigation on Countermeasures for Earthquakes and Tsunami Based on the Lessons Learned from the ”Great East Japan Earthquake” (2011) of the Central Disaster Management Council has responded to the Great East Japan Earthquake by proposing that basically, two levels of tsunami must be hypothesized to build future tsunami countermeasures. One is a tsunami hypothesized to build comprehensive disaster prevention countermeasures centered on evacuation of residents. It is set based on a survey of tsunami deposits formed over an ultra-long period and observations of crustal movement, and it is a maximum class tsunami which, although it occurs extremely rarely, causes devastating damage when it does occur. One more is a tsunami which is hypothesized to build coastal protection facilities such as breakwaters and other structures which prevent tsunami from inundating inland regions. It is a tsunami which occurs more often than the maximum class tsunami, and altho...

Research paper thumbnail of 高精度ISPH法による直立壁面上の砕波の数値解析

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2014

A numerical wave flume based on a particle method is a key tool for a design of coastal structure... more A numerical wave flume based on a particle method is a key tool for a design of coastal structure under the action of extremely large and strongly nonlinear wave forces. The SPH, which is the predominant method in the international research society, contains unphysical artificial viscosity due to its explicit algorithm. The ISPH method evades the artiflcial viscosity by introducing semi-implicit algorithm, however it suffers from another drawback, namely a pressure fluctuation. In this study, accurate schemes, which have been developed to enhance a stability of pressure in the MPS method, are applied to the ISPH method, with examining their applicability through some benchmark tests.

Research paper thumbnail of ISPH法による越流に伴う防潮堤背後の洗掘計算

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2015

Research paper thumbnail of 杭係留方式浮桟橋の津波外力推定に関する考察

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2014

In this paper, responses of a pontoon in tsunami were studied. As an example, a pontoon by the mo... more In this paper, responses of a pontoon in tsunami were studied. As an example, a pontoon by the mooring pile system of Izushima fishing port in Miyagi Pref. was treated. The pile of the pontoon was pulled out of the tsunami which was derived from the Great East Japan Earthquake. Model tests in a solitary wave was carried out and tsunami simulation was also carried out. The pontoon was capsized in fast elevating cases of water surface. In order to suppress the capsizing, it is effective to place the roller fender lower than the gravity center to increase restoring moment. According to the tsunami simulation for Izushima fishing port, tsunami height was small enough compared to the wave length and elevation speed was slow. Thus, the pullout force of the pile is estimated mainly from surplus buoyancy, and capsizing should not be occurred.

Research paper thumbnail of Hydraulic Model Experiment and Numerical Calculation on Scour

Research paper thumbnail of Performance of Soft-first-story Buildings against Earthquake Motions and Tsunami Loadings

A series of earthquake and tsunami loading tests of reinforced concrete buildings with soft-first... more A series of earthquake and tsunami loading tests of reinforced concrete buildings with soft-first story were conducted to identify the effects of earthquake shaking preceding to the tsunami loading, which might cause the collapse of the structure. The dynamic and hydraulic tests were conducted in 2014 and the static tests in 2015 totally for five specimens out of six specimens constructed. Three specimens were tested at hydraulic testing laboratory at PARI, Kurihama, in the first series of 2014 under earthquake loading and tsunami loading. The first specimen with 50 mm square column was tested under hydraulic loading with water height of 1.0 m and survived the hydraulic loading without collapse. The second specimen with the same dimensions of 50 mm square was subjected to dynamic loading first with the maximum acceleration of 0.4 G and then the same tsunami loading of 1.0 m, in case the specimen collapsed totally under hydraulic loading. The third specimen with 75 mm square columns ...

Research paper thumbnail of Hindcasting the Storm Surge During the 2017 Hurricane Irma on Minor Islands

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2019

Research paper thumbnail of Solving the Puzzle of the September 2018 Palu, Indonesia, Tsunami Mystery: Clues from the Tsunami Waveform and the Initial Field Survey Data

Journal of Disaster Research, 2018

On September 28, 2018, following a magnitude 7.5 strike-slip fault earthquake, an unexpected tsun... more On September 28, 2018, following a magnitude 7.5 strike-slip fault earthquake, an unexpected tsunami inundated the coast of Palu bay, Sulawesi, Indonesia, causing many casualties and extensive property damage. However, the earthquake’s mechanism rarely generates a destructive tsunami. The tidal record at Pantoloan, located along the coast of Palu bay, indicates that the tsunami arrived 6 min after the earthquake and generated 2 m of receding water. It had a maximum wave height of 2 m and arrived approximately 2 min later. The tsunami had a relatively short period and caused devastation as far inland as 300 m. Additionally, 8 m high watermarks were observed near the coast; the flow depth decreased to 3.5 m inland (Fig. 1). Amateur videos and eyewitness accounts indicate that the tsunami did not enter the bay through its mouth but obliquely from an area inside the bay. Our hypothesis, therefore, is that the killer tsunami was most likely generated by an underwater landslide occurring ...

Research paper thumbnail of Effect on Scour Depth of Falling Height of Overflow

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2016

Research paper thumbnail of Future Challenges to Address Climate Change in Japanese Coastal Areas

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2021

Research paper thumbnail of 1 Numerical Analysis of Bulk Drag Coefficient in Dense Vegetation by Immersed Boundary Method

In this paper, bulk drag coefficient in rigid dense vegetation is investigated mainly by using a ... more In this paper, bulk drag coefficient in rigid dense vegetation is investigated mainly by using a three dimensional numerical simulation model CADMAS-SURF/3D by incorporating Immersed Boundary Method to calculate flow around the vertical cylinder in the Cartesian grid. Large Eddy Simulation is also incorporated as a turbulence model. Firstly, validation of the developed model is conducted with a single cylinder in the flow field based on literature. All the results obtained here (Re=300, 3,900 and 8,000) show good agreement with the reference data in literature. After the validation, multiple cylinders are allotted in three different densities (S/D=2.8, 2.0, 1.4) in a numerical wave tank and numerical simulations are conducted to investigate bulk drag coefficient. The result shows that the ratio of bulk drag coefficient to drag coefficient, which represents a reduction, is not just a function of density but a function of parameter 2a/S, in which 2a is stroke of the motion and S is cy...

Research paper thumbnail of Calculation Method of Uplift Forces at Pier Based on Gas-Liquid Phase Flow Model

Coastal Engineering Proceedings

Seaside facilities such as pier are affected by uplift forces due to storm surge and waves caused... more Seaside facilities such as pier are affected by uplift forces due to storm surge and waves caused by typhoons. Therefore, detailed knowledge of external force is required for designing the pier (Tanimoto et al., 1978). Previously, the elucidation of the uplift forces and the shock wave pressure has been a major issue. Indeed, it has been clarified by experiments. Bagnold (1939) conducted an experimental study for revealing the relationship between the air layer and the pressure value, and found that air, which is a compressible fluid, reduces the pressure value. Furthermore, air has the effect for prolonging the action time. Arikawa and Yamano (2009) conducted the numerical simulation of shock breaking wave pressure by considering the inclusion of gas, and it was shown that the shock wave pressure after breaking wave can be reproduced. However, there are few cases that numerical calculation is considered for phenomena such as lifting pressure that are greatly affected by air. In thi...

Research paper thumbnail of Applicability of the Vertical Telescopic Breakwater Using the Past Typhoon in Tokyo Bay

Coastal Engineering Proceedings

The vertical telescopic breakwater(VTB), which is a new breakwater that permits the navigation of... more The vertical telescopic breakwater(VTB), which is a new breakwater that permits the navigation of ships, remain at the bottom of the sea during calm and rise to the surface during tsunamis or storm surges. Kawai et al. (2017) and Arikawa et al. (2019) found that it is effective not only for swell waves, but also for long-period waves simulating tsunamis and storm surges by previous experiments and numerical analyses. However, there have been few studies on the performance of VTB by numerical calculations in actual ports using actual typhoons. In addition, sea levels and changes in characteristics of typhoon due to climate change are predicted to occur; hence, we are concerned about the damage in all quarters caused by storm surge inundation, especially at Tokyo. Therefore, in this study, we used hypothetical typhoons under worst-case scenarios and quantitatively evaluated the protection performance of VTB against hypothetical typhoons with different aperture rates of VTB in Tokyo Ba...

Research paper thumbnail of The Examination of Collision Speed Reduction Effect of Tsunami Debris at the Tip of Runup Wave by Reflected Wave

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2020

Research paper thumbnail of Experimental Study on Local Scour at the Base of a Monopile Offshore Wind Generator

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2020

Research paper thumbnail of Protective Performance of Movable Breakwaters Against Storm Surge and Tsunami

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2019

Research paper thumbnail of Experimental Study for Wave Pressure of the Covering State of Wave-Dissipating Blocks

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2009

Research paper thumbnail of 大規模水理模型実験による津波・高波に対する直立浮上式防波堤の水理特性に関する研究

PROCEEDINGS OF CIVIL ENGINEERING IN THE OCEAN, 2007

Research paper thumbnail of 防波堤の腹付け被覆ブロックの安定性

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2014

One of the possible basic structural countermeasures taken for a breakwater to protect foundation... more One of the possible basic structural countermeasures taken for a breakwater to protect foundation mound and seabed against scouring caused by overflow is widening work for increasing the height of the foundation mound behind the breakwater. The widening work behind the caissons is topped with scour prevention work and a revetment to provide scour resistance to the structure. But the stability of armour blocks on the widening works is not cleared. In this report, the physical experiments were conducted to make clear the mechanism of failure of armour blocks under overflow of tsunami, and to consider the estimation methodology of stability of armour blocks. The results indicated that the stability of blocks related with the porosity of blocks and was estimated by using Isbash equations.

Research paper thumbnail of 避難途中に津波によって溺れる危険性の検討

PROCEEDINGS OF CIVIL ENGINEERING IN THE OCEAN, 2008

Kimihiko ENDOU and Taro ARIKAWA The primary objective of tsunami disaster mitigation is to reduce... more Kimihiko ENDOU and Taro ARIKAWA The primary objective of tsunami disaster mitigation is to reduce the casualties. The major cause of the deaths is drowning by tsunami current, especially during evacuation. In the paper, the causes of deaths are discussed through reference to past experiences. A fault tree is presented to summarize the physical danger posed by tsunami waves to the human body, and the personal danger is discussed based on the tree. The stability of the human body against wave front collision and tsunami currents is discussed and threshold conditions are proposed. The time for evacuation is usually very limited and the risk of encountering a tsunami during evacuation is often high. Walking in inundated areas during a tsunami attack is especially dangerous. Vertical evacuation is highly recommended.

Research paper thumbnail of Consideration to the resiliency of protective structures against tsunami by using High Performance Computer

Japan Geoscience Union, 2014

The Committee for Technical Investigation on Countermeasures for Earthquakes and Tsunami Based on... more The Committee for Technical Investigation on Countermeasures for Earthquakes and Tsunami Based on the Lessons Learned from the ”Great East Japan Earthquake” (2011) of the Central Disaster Management Council has responded to the Great East Japan Earthquake by proposing that basically, two levels of tsunami must be hypothesized to build future tsunami countermeasures. One is a tsunami hypothesized to build comprehensive disaster prevention countermeasures centered on evacuation of residents. It is set based on a survey of tsunami deposits formed over an ultra-long period and observations of crustal movement, and it is a maximum class tsunami which, although it occurs extremely rarely, causes devastating damage when it does occur. One more is a tsunami which is hypothesized to build coastal protection facilities such as breakwaters and other structures which prevent tsunami from inundating inland regions. It is a tsunami which occurs more often than the maximum class tsunami, and altho...

Research paper thumbnail of 高精度ISPH法による直立壁面上の砕波の数値解析

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2014

A numerical wave flume based on a particle method is a key tool for a design of coastal structure... more A numerical wave flume based on a particle method is a key tool for a design of coastal structure under the action of extremely large and strongly nonlinear wave forces. The SPH, which is the predominant method in the international research society, contains unphysical artificial viscosity due to its explicit algorithm. The ISPH method evades the artiflcial viscosity by introducing semi-implicit algorithm, however it suffers from another drawback, namely a pressure fluctuation. In this study, accurate schemes, which have been developed to enhance a stability of pressure in the MPS method, are applied to the ISPH method, with examining their applicability through some benchmark tests.

Research paper thumbnail of ISPH法による越流に伴う防潮堤背後の洗掘計算

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2015

Research paper thumbnail of 杭係留方式浮桟橋の津波外力推定に関する考察

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2014

In this paper, responses of a pontoon in tsunami were studied. As an example, a pontoon by the mo... more In this paper, responses of a pontoon in tsunami were studied. As an example, a pontoon by the mooring pile system of Izushima fishing port in Miyagi Pref. was treated. The pile of the pontoon was pulled out of the tsunami which was derived from the Great East Japan Earthquake. Model tests in a solitary wave was carried out and tsunami simulation was also carried out. The pontoon was capsized in fast elevating cases of water surface. In order to suppress the capsizing, it is effective to place the roller fender lower than the gravity center to increase restoring moment. According to the tsunami simulation for Izushima fishing port, tsunami height was small enough compared to the wave length and elevation speed was slow. Thus, the pullout force of the pile is estimated mainly from surplus buoyancy, and capsizing should not be occurred.

Research paper thumbnail of Hydraulic Model Experiment and Numerical Calculation on Scour

Research paper thumbnail of Performance of Soft-first-story Buildings against Earthquake Motions and Tsunami Loadings

A series of earthquake and tsunami loading tests of reinforced concrete buildings with soft-first... more A series of earthquake and tsunami loading tests of reinforced concrete buildings with soft-first story were conducted to identify the effects of earthquake shaking preceding to the tsunami loading, which might cause the collapse of the structure. The dynamic and hydraulic tests were conducted in 2014 and the static tests in 2015 totally for five specimens out of six specimens constructed. Three specimens were tested at hydraulic testing laboratory at PARI, Kurihama, in the first series of 2014 under earthquake loading and tsunami loading. The first specimen with 50 mm square column was tested under hydraulic loading with water height of 1.0 m and survived the hydraulic loading without collapse. The second specimen with the same dimensions of 50 mm square was subjected to dynamic loading first with the maximum acceleration of 0.4 G and then the same tsunami loading of 1.0 m, in case the specimen collapsed totally under hydraulic loading. The third specimen with 75 mm square columns ...

Research paper thumbnail of Hindcasting the Storm Surge During the 2017 Hurricane Irma on Minor Islands

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2019

Research paper thumbnail of Solving the Puzzle of the September 2018 Palu, Indonesia, Tsunami Mystery: Clues from the Tsunami Waveform and the Initial Field Survey Data

Journal of Disaster Research, 2018

On September 28, 2018, following a magnitude 7.5 strike-slip fault earthquake, an unexpected tsun... more On September 28, 2018, following a magnitude 7.5 strike-slip fault earthquake, an unexpected tsunami inundated the coast of Palu bay, Sulawesi, Indonesia, causing many casualties and extensive property damage. However, the earthquake’s mechanism rarely generates a destructive tsunami. The tidal record at Pantoloan, located along the coast of Palu bay, indicates that the tsunami arrived 6 min after the earthquake and generated 2 m of receding water. It had a maximum wave height of 2 m and arrived approximately 2 min later. The tsunami had a relatively short period and caused devastation as far inland as 300 m. Additionally, 8 m high watermarks were observed near the coast; the flow depth decreased to 3.5 m inland (Fig. 1). Amateur videos and eyewitness accounts indicate that the tsunami did not enter the bay through its mouth but obliquely from an area inside the bay. Our hypothesis, therefore, is that the killer tsunami was most likely generated by an underwater landslide occurring ...

Research paper thumbnail of Effect on Scour Depth of Falling Height of Overflow

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2016

Research paper thumbnail of Future Challenges to Address Climate Change in Japanese Coastal Areas

Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering), 2021

Research paper thumbnail of 1 Numerical Analysis of Bulk Drag Coefficient in Dense Vegetation by Immersed Boundary Method

In this paper, bulk drag coefficient in rigid dense vegetation is investigated mainly by using a ... more In this paper, bulk drag coefficient in rigid dense vegetation is investigated mainly by using a three dimensional numerical simulation model CADMAS-SURF/3D by incorporating Immersed Boundary Method to calculate flow around the vertical cylinder in the Cartesian grid. Large Eddy Simulation is also incorporated as a turbulence model. Firstly, validation of the developed model is conducted with a single cylinder in the flow field based on literature. All the results obtained here (Re=300, 3,900 and 8,000) show good agreement with the reference data in literature. After the validation, multiple cylinders are allotted in three different densities (S/D=2.8, 2.0, 1.4) in a numerical wave tank and numerical simulations are conducted to investigate bulk drag coefficient. The result shows that the ratio of bulk drag coefficient to drag coefficient, which represents a reduction, is not just a function of density but a function of parameter 2a/S, in which 2a is stroke of the motion and S is cy...

Research paper thumbnail of Calculation Method of Uplift Forces at Pier Based on Gas-Liquid Phase Flow Model

Coastal Engineering Proceedings

Seaside facilities such as pier are affected by uplift forces due to storm surge and waves caused... more Seaside facilities such as pier are affected by uplift forces due to storm surge and waves caused by typhoons. Therefore, detailed knowledge of external force is required for designing the pier (Tanimoto et al., 1978). Previously, the elucidation of the uplift forces and the shock wave pressure has been a major issue. Indeed, it has been clarified by experiments. Bagnold (1939) conducted an experimental study for revealing the relationship between the air layer and the pressure value, and found that air, which is a compressible fluid, reduces the pressure value. Furthermore, air has the effect for prolonging the action time. Arikawa and Yamano (2009) conducted the numerical simulation of shock breaking wave pressure by considering the inclusion of gas, and it was shown that the shock wave pressure after breaking wave can be reproduced. However, there are few cases that numerical calculation is considered for phenomena such as lifting pressure that are greatly affected by air. In thi...

Research paper thumbnail of Applicability of the Vertical Telescopic Breakwater Using the Past Typhoon in Tokyo Bay

Coastal Engineering Proceedings

The vertical telescopic breakwater(VTB), which is a new breakwater that permits the navigation of... more The vertical telescopic breakwater(VTB), which is a new breakwater that permits the navigation of ships, remain at the bottom of the sea during calm and rise to the surface during tsunamis or storm surges. Kawai et al. (2017) and Arikawa et al. (2019) found that it is effective not only for swell waves, but also for long-period waves simulating tsunamis and storm surges by previous experiments and numerical analyses. However, there have been few studies on the performance of VTB by numerical calculations in actual ports using actual typhoons. In addition, sea levels and changes in characteristics of typhoon due to climate change are predicted to occur; hence, we are concerned about the damage in all quarters caused by storm surge inundation, especially at Tokyo. Therefore, in this study, we used hypothetical typhoons under worst-case scenarios and quantitatively evaluated the protection performance of VTB against hypothetical typhoons with different aperture rates of VTB in Tokyo Ba...