Updated on 2022/11/26

写真a

 
SEKINE, Masato
 
Scopus Paper Info  
Paper Count: 0  Citation Count: 0  h-index: 1

Citation count denotes the number of citations in papers published for a particular year.

Affiliation
Faculty of Science and Engineering, School of Creative Science and Engineering
Job title
Professor

Concurrent Post

  • Affiliated organization   Art and Architecture School

  • Faculty of Science and Engineering   Graduate School of Creative Science and Engineering

  • Affiliated organization   Global Education Center

Research Institute

  • 2020
    -
    2022

    理工学術院総合研究所   兼任研究員

Degree

  • Waseda University   Doctor of Engineering

Professional Memberships

  •  
     
     

    日本自然災害学会

  •  
     
     

    International Association for Hydraulic Engineering and Research

  •  
     
     

    International Association for Hydraulic Engineering and Research

  •  
     
     

    American Society of Civil Engineers

  •  
     
     

    Japan Society of Erosion Control Engineering

  •  
     
     

    Japan Society of Civil Engineers

  •  
     
     

    Japan Society of Civil Engineers

  •  
     
     

    Japan Society of Civil Engineers

  •  
     
     

    Japan Society of Civil Engineers

  •  
     
     

    Japan Society of Civil Engineers

  •  
     
     

    Japan Society of Civil Engineers

  •  
     
     

    Japan Society of Civil Engineers

  •  
     
     

    Japan Society of Civil Engineers

▼display all

 

Research Areas

  • Hydroengineering

Research Interests

  • River Engineering, Hydraulics, River Mechanics

Papers

  • 豪雨・高潮による東京都23区の大規模浸水プロセスと下水道が果たす役割

    関根正人, 小方公美子, 馬場航

    日本下水道協会第56回下水道研究発表会講演集     203 - 205  2019.07  [Refereed]

  • 集中豪雨による鶴見川流域の浸水拡大プロセスと​これに及ぼす下水道の効果

    関根正人, 竹村尚樹, 馬場航

    日本下水道協会第56回下水道研究発表会講演集     200 - 202  2019.07  [Refereed]

  • 高度に都市化された川崎市東部を​対象とした豪雨時の浸水リスク評価

    関根正人, 吉野萌

    日本下水道協会第56回下水道研究発表会講演集     197 - 199  2019.07  [Refereed]

  • 模擬河川堤防の決壊プロセスに与える堤体材料の礫・砂・粘土の混合比率の影響

    関根正人, 菅俊貴, 松浦泰地

    土木学会論文集B1(水工学)   75 ( 4 )  2019  [Refereed]

  • 大礫群の間隙に露出する大粒径の砂礫がさらに小さな砂の移動に及ぼす遮蔽効果

    平松裕基, 本合弘樹, 関根正人

    土木学会論文集B1(水工学)   75 ( 4 )  2019  [Refereed]

  • 豪雨・高潮時に発生する東京都23区の大規模浸水プロセス

    関根正人, 馬場航, 小方公美子

    土木学会論文集B1(水工学)   75 ( 4 )  2019  [Refereed]

  • 横浜・川崎を対象とした2016年8月22日豪雨時の浸水の再現計算

    関根正人, 竹村尚樹, 馬場航, 吉野萌

    土木学会論文集B1(水工学)   75 ( 4 )  2019  [Refereed]

  • 横浜市東部を対象とした豪雨時の浸水リスク評価

    関根正人, 馬場航

    日本下水道協会第55回下水道研究発表会講演集     128 - 130  2018.07

  • 荒川決壊時を想定した大規模浸水とプロセスとこれに及ぼす下水道からの逆流水の影響

    関根正人, 古川侑里

    日本下水道協会第55回下水道研究発表会講演集     125 - 127  2018.07

  • 高潮時に東京都23区で発生する浸水拡大プロセスと下水道の効果

    関根正人, 小方公美子

    日本下水道協会第55回下水道研究発表会講演集     122 - 124  2018.07

  • 横浜市東部を対象とした豪雨時の浸水プロセスとリスク情報の効果的な表示方法(登載決定)

    関根正人, 馬場航, 竹村尚樹, 中山裕貴

    土木学会論文集B1(水工学)   74 ( 5 )  2018

  • 粘土河床上に配置した模擬巨石による砂礫の捕捉効果と河床変動プロセス(登載決定)

    関根正人, 芦澤穂波, 佐藤裕, 吉川文崇

    土木学会論文集B1(水工学)   74 ( 5 )  2018

  • 河道湾曲部で発生する粘着性河床の変動プロセスに及ぼす掃流砂礫の影響(登載決定)

    関根正人, 佐藤裕, 芦澤穂波, 吉川文崇

    土木学会論文集B1(水工学)   74 ( 5 )  2018

  • 大礫群の間隙に存在する掃流砂として輸送される砂礫の三次元構造(登載決定)

    平松裕基, 本合弘樹, 関根正人

    土木学会論文集B1(水工学)   74 ( 5 )  2018

  • 模擬河川堤防の決壊プロセスに及ぼす含有する砂礫・粘土の影響に関する検討(登載決定)

    関根正人, 佐藤耕介, 菅俊貴

    土木学会論文集B1(水工学)   74 ( 5 )  2018

  • 高潮により引き起こされる東京都23 区の浸水被害拡大プロセス(登載決定)

    関根正人, 小方 公美子

    土木学会論文集B1(水工学)   74 ( 5 )  2018

  • 越流による模擬河川堤防の決壊プロセスに関する検討

    関根正人, 堀江翼, 佐藤耕介

    土木学会論文集B1(水工学)   74 ( 4 ) I_1057 - I_1062  2018

  • 砂礫の移動に起因する粘土河床の浸食促進・抑制効果と河床変動プロセス

    関根正人, 池田憲昭, 芦澤穂波, 佐藤裕

    土木学会論文集B1(水工学)   74 ( 4 ) I_1087 - I_1092  2018

  • 骨格が大礫により構成される河床上で生じる鉛直分級のメカニズム

    関根正人, 平松裕基, 中川裕貴

    土木学会論文集B1(水工学)   74 ( 4 ) I_1069 - I_1074  2018

  • 東京東部低平地を対象とした大規模浸水予測

    関根正人, 柴田祐希, 小方公美子, 中山裕貴

    土木学会論文集B1(水工学)   74 ( 4 ) I_1531 - I_1536  2018

  • 交通渋滞が道路冠水に及ぼす影響に関わる数値計算による検討

    関根正人, 斎藤涼太

    土木学会論文集B1(水工学)   74 ( 4 ) I_1309 - I_1314  2018

  • 東京都23区を対象とした豪雨時浸水リスク評価とアンダーパスの冠水事前予測

    関根正人, 児玉香織

    土木学会論文集B1(水工学)   74 ( 4 ) I_1543 - I_1548  2018

  • 街路ネットワーク浸水・氾濫解析モデルを用いた東京東部低平地の浸水危険度評価

    関根正人, 中山裕貴, 小方公美子, 柴田祐希

    日本下水道協会第54回下水道研究発表会講演集     161 - 163  2017.07

  • 豪雨域の移動方向が下水道ならびに都市河川への雨水集中と都市浸水に及ぼす影響

    関根正人, 中森奈波, 近藤恭平

    日本下水道協会第54回下水道研究発表会講演集     164 - 166  2017.07

  • 集中豪雨による東京都心部の浸水プロセスと都市河川の洪水に及ぼす下水道の効果

    関根正人, 児玉香織, 斎藤涼太, 中森奈波

    日本下水道協会第54回下水道研究発表会講演集     158 - 160  2017.07

  • Gravel sorting and variation of riverbeds containing gravel, sand, silt and clay

    Masato Sekine, Yuki Hiramatsu

    John Wiley & Sons, Ltd, Gravel-Bed Rivers: Processes and Disasters     591 - 608  2017

  • 森ヶ崎処理区を対象とした2013年7月23日豪雨時の都市浸水の再現計算とその精度検証

    関根正人, 中森奈波, 児玉香織, 斎藤涼太

    土木学会論文集B1(水工学)   73 ( 4 ) I_1459 - I_1464  2017

  • 荒川決壊を想定した東京東部低平地の大規模浸水と避難に関わるリスクの評価

    関根正人, 小林香野

    土木学会論文集B1(水工学)   73 ( 4 ) I_1453 - I_1458  2017

  • 粘土を含有した模擬河川堤防の決壊プロセスに関する実験的検討

    関根正人, 佐野正太, 鈴木昌宏, 堀江翼

    土木学会論文集B1(水工学)   73 ( 4 ) I_817 - I_822  2017

  • 石神井川流域を対象とした豪雨時の都市浸水と河川洪水の同時予測計算

    関根正人, 近藤恭平, 神山宙大, 小林香野

    日本下水道協会第53回下水道研究発表会講演集     139 - 141  2016.07

  • 荒川破堤時に発生する大規模浸水とそのプロセスに及ぼす下水道の影響

    関根正人, 小林香野

    日本下水道協会第53回下水道研究発表会講演集     136 - 138  2016.07

  • 数値予測による豪雨時の東京都森ヶ崎下水道処理区内の浸水危険度評価

    関根正人, 児玉香織, 斉藤涼太, 中森奈波

    日本下水道協会第53回下水道研究発表会講演集     133 - 135  2016.07

  • 東京都心部の地下空間への氾濫水の流入危険度とトンネル内の浸水域拡大過程に関する検討

    関根正人, 関根貴広

      72 ( 4 ) I_1369 - I_1374  2016

  • 石神井川流域を対象とした豪雨時の内水氾濫と河川洪水流の一体予測計算

    関根正人, 近藤恭平, 神山宙大, 小林香野

    土木学会論文集B1(水工学)   72 ( 4 ) I_337 - I_342  2016

  • Sediment Run-Out Processes and Possibility of Sediment Control Structures in the 2013 Izu-Ohshima Event

    EGASHIRA Shinji, TAKEBAYASHI Hiroshi, SEKINE Masato, OSANAI Nobutomo

    International Journal of Erosion Control Engineering   9 ( 4 ) 155 - 164  2016

     View Summary

    Typhoon No. 26 in 2013 attacked the Izu-Oshima Island with record heavy rainfall and caused a disaster resulting from landslides and mud flows. This extreme event is the motivation of our study on how we evaluate hazardous zones at risk of mud flows and how we design structural and non-structural measures accordingly. The present study describes sediment runout processes, mud flow control by means of a guide wall, and a method to evaluate topological conditions in which landslides and mud flows avalanche into unexpected areas. The landslides took place in the western slope of Izu-Oshima, which is only about 2500m wide. Analyses on phase shifting from solid to liquid as well as on mobility of the soil masses suggest that the soil masses released by the landslides transformed directly into mud flows, and that the mud flows developed in size through sediment erosion in their run-out processes. The predicted results by means of a numerical model based on depth-integrated governing equations of sediment-water mixture flow suggest that mud flows could be controlled well using a guide wall, which shows a high possibility of mud flow control using a storage structure with a guide wall. In addition, we propose a simple method to evaluate topological conditions to judge whether mud flows will enter unexpected areas, which will provide a key to identify hazardous zones including even those that have been missed out conventionally.

    DOI CiNii

  • 石神井川流域を対象とした集中豪雨時の浸水危険度に関する数値予測

    関根正人, 神山宙大, 小林香野, 近藤恭平

    日本下水道協会第52回下水道研究発表会講演集     149 - 151  2015.07

  • X-Rainによる豪雨データを用いた都心部のリアルタイム浸水予報に向けた試み

    関根正人, 関根貴広, 古木雄

    日本下水道協会第52回下水道研究発表会講演集     146 - 148  2015.07

  • EROSION PROCESS OF CLAY RIVERBED BY SAND TRANSPORT AND VERTICAL STRUCTURE OF THE BED

    SEKINE Masato, NOMOTO Takami, TAKANO Hirotaka

    Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering)   71 ( 4 ) I_859 - I_864  2015

     View Summary

    Erosion process of clay riverbed was investigated. The clay riverbed is eroded by the action of water flow. It is also eroded by moving sand and gravel. In this study, the influence of moving sand and gravel on erosion of the clay is investigated. This process is affected by the amount of sand and gravel transport in the river. Movable bed experiments were conducted under the several conditions of both the flow discharge and the rate of sediment supply. As a result, we found that the relationship between the erosion rate of the clay riverbed and the rate of supplied sand has extreme value. It was also found characteristic vertical structure under the bed surface.

    DOI CiNii

  • VERTICAL STRUCTURE OF THE DYNAMIC EQUILIBRIUM STATE OF RIVERBED WITH LARGER STONES

    HIRAMATSU Yuki, SEKINE Masato, KENMOTSU Naoki

    Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering)   71 ( 4 ) I_865 - I_870  2015

     View Summary

    Experimental investigation was conducted on the dynamic equilibrium state of bed which was composed of extremely wide range of sediment. A void of larger stones was filled with medium gravel which moves as bed load and finer sand which moves as suspended load. Experiment was conducted with supplying gravel and sand. The flow discharge and the sediment supply discharge of gravel were set as fixed value, and the sediment discharge of sand was changed. The layer of only gravel was exposed on the bed surface under the condition that the discharge of sand was small. On the other hand, if the supplying rate of sand was large, the layer which was composed of both gravel and sand was formed below the bed surface. It was verified that this results were not changed even if the flow rate and the discharge of gravel changed.

    DOI CiNii

  • NUMERICAL PREDICTION OF URBAN INUNDATION IN THE KANDA RIVER BASIN

    SEKINE Masato, ASAI Koichi

    Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering)   71 ( 4 ) I_1429 - I_1434  2015

     View Summary

    The Kanda river basin is a highly-urbanized area located next to the Tokyo metropolitan area. In this area, most ground was paved, and high density drain network has been constructed under the ground. Because of such condition, rain water concentrates rapidly to the drainage pipe, and it flows into urban river system. In this study, numerical simulation was conducted to investigate a process of urban inundation in this basin by focusing on the interaction between river and drainage system. Two rain events, Suginami torrential rain in 2005 and heavy rain event on June, 29 in 2014, were paid attention in this study. In the latter case, the rain data by X-MP radar which was provided by MLIT was applied. As a result of this analysis, it was revealed where the points with higher inundation risk lay hidden in this basin.

    DOI CiNii

  • NUMERICAL SIMULATION OF INUNDATION IN URBAN AREA OF TOKYO AND UNDERGROUND SPACE

    SEKINE Masato, FURUKI Yu, SEKINE Takahiro

    Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering)   71 ( 4 ) I_1435 - I_1440  2015

     View Summary

    Recently extremely strong rain came to attack the urban areas of Tokyo. As a result, urban inundation came to be frequent. Because there are several underground spaces including subway stations in this highly urbanized area in Tokyo, appropriate measures must be taken beforehand. Numerical simulation is effective to reduce damage of the inundation. In this study, we applied numerical prediction technique developed by the first author to the Tokyo downtown area. Based on the result, the inundation risk of the actual large-scale underground was made clear.

    DOI CiNii

  • 三河島下水道処理区を対象とした東京都心部の内水氾濫危険性評価に関する数値解析

    関根正人, 関根貴広, 井上優香

    日本下水道協会第51回下水道研究発表会講演集     208 - 210  2014.07

  • 芝浦処理区を対象とした集中豪雨時の浸水危険性評価に関する数値解析

    関根正人, 古木雄, 竹順哉

    日本下水道協会第51回下水道研究発表会講演集     205 - 207  2014.07

  • REAL-TIME PREDICTION OF INUNDATION BY USING HIGH-RESOLUTION RAIN DATA OF X-BAND LADAR

    SEKINE Masato, ASAI Koichi, FURUKI Yu

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   70 ( 4 ) I_1423 - I_1428  2014

     View Summary

    Recently, the warming on the earth advances gradually. Under such circumstances, occurrence frequency of the torrential rain increases in Tokyo. The technique of numerical prediction of the inundation is an effective tool in order to reduce damage due to such a torrential rain in urban area. In this study, the numerical prediction was conducted by using the rain data of the X-band MP radar as the first step to realize a real-time inundation forecast at the time of the localized torrential rain occurrence. Inundation in Shinjuku area that was highly-urbanized was investigated in this study by using the actual rain data that was measured locally on August 26, 2011. It was suggested that an inundation forecast could be realized soon in future.

    DOI CiNii

  • NUMERICAL SIMULATION OF INUNDATION IN LOWLAND AREAS OF EAST TOKYO

    SEKINE Masato, IKEDA Ryo

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   70 ( 4 ) I_1429 - I_1434  2014

     View Summary

    In this study, inundation process in lowland areas of Tokyo which is bordered by the Ara River and the Sumida River was investigated numerically. Numerical technique developed by the first author was applied in order to estimate how hazardous the urban lowland area under two different conditions. The state of inundation which is caused by a localized torrential rain was predicted. Inundation rocess in this area was also investigated numerically under the assumption that the overflow from the Ara River into this area occurred. As a result of these simulations, the time series of information about the flow path of inundated water were obtained, and the aracteristics of inundation in this area were made clear.

    DOI CiNii

  • EXPERIMENTAL STUDY ON THE DYNAMIC EQUILIBRIUM STATE OF RIVERBED WITH LARGER STONE CONSTITUTING THE BED FRAME

    HIRAMATSU Yuki, SEKINE Masato, KADOI Yuki, KENMOTSU Naoki

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   70 ( 4 ) I_955 - I_960  2014

     View Summary

    The objective of this study is to clarify the deformation process of river bed which is composed of extremely wide range of sediment. The frame of bed is constituted by the larger rock or stone which cannot move at all. In this study, "the dynamic equilibrium state of river bed" was investigated experimentally. The flow discharge and the sediment discharge of supply were the parameters in experiment. The sand and gravel existing in a void of the stones of the large particle size is affected by the stones. It is called a hiding effect. It was found from this study that the riverbed reaches different dynamic equilibrium state according to a supplying rate of the sand or gravel, and the surface elevation of sand and gravel exposed on the riverbed surface changes.

    DOI CiNii

  • EXPERIMENTAL STUDY ON BARE-SLOPE EROSION CAUSED BY RAINFALL AND CHANNEL NETWORK FORMATION

    SEKINE Masato, TADA Atsushi, ISHIKAWA Manabu

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   70 ( 4 ) I_913 - I_918  2014

     View Summary

    Experimental investigations were conducted on the process of surface erosion and channel network formation on the bare slope. This is the process of sediment yields on the river basin. Some experiments were conducted to clarify the process of the erosion by varying both the gradient of slope and the width of mouth at the downstream end. It was found that characteristics of channels were different among the experiments, such as length, width, branches and interruptions. As a result, it became clear that the steepness of slope affects the length of the channel network in longitudinal direction. The width of the mouth, on the other hand, affected the width and the pattern of channel network in lateral direction.

    DOI CiNii

  • NUMERICAL SIMULATION OF BARE-SLOPE EROSION CAUSED BY RAINFALL AND CHANNEL NETWORK FORMATION

    SEKINE Masato

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   70 ( 4 ) I_919 - I_924  2014

     View Summary

    Fundamental process of surface erosion on bare slope which is caused by artificial rainfall was studied in this study. Numerical simulation was attempted under the same condition as the experiment that we conducted at the same time. Investigations were carried out for two type of the bare slope. Erosion process of the bare slope of sand which contains clay by 12% was one of the targets of this study. Numerical predictions technique was newly developed in consideration of being a non-equilibrium sediment transport process. Results of the numerical computation agreed well with experimental results, and the validity of the technique was confirmed.

    DOI CiNii

  • 東京都心部を対象とした集中豪雨時の浸水危険性評価に関する数値解析

    関根正人, 竹順哉

    日本下水道協会第50回下水道研究発表会講演集     211 - 213  2013.07

  • 住宅密集地を対象とした集中豪雨時の浸水氾濫過程に関する数値解析

    関根正人, 佐藤裕隆, 和田祐樹

    日本下水道協会第50回下水道研究発表会講演集     208 - 210  2013.07

  • Equilibrium state of river bed with three grain size groups of sediment

    M. Sekine, Y. Hiramatsu, Y. Kadoi

    The 12th International Symposium on River Sedimentation     393 - 400  2013

  • NUMERICAL SIMULATION OF INUNDATION ON ROADS AND IN UNDERGROUND SPACES IN HIGHLY URBANIZED AREA OF THE CENTER OF TOKYO

    SEKINE Masato, TAKE Junya

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   69 ( 4 ) I_1567 - I_1572  2013

     View Summary

    Recently, we often experience a localized torrential rain whose intensity is much larger than the design value for drainage network system. Numerical simulation ofinundation was conducted in order to estimate how hazardous the highly urbanized area of center of Tokyo is if such a heavy rain attacks there. There are several underground spaces including subway stations there, and a number of gates for stairs toward the space exist in the spots where the ground elevation is lower than the surrounding area. As a result of this study, it was concluded that serious inundation may occur in large scale underground space in this area. We also found out the gates leading to the space through which water flowing on road can enter.

    CiNii

  • EFFECT OF SAND TRANSPORT ON DEFORMATION OF BED WITH COHESIVE SEDIMENT

    SEKINE Masato, OKA Yukihiro, NOMURA Masakazu

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   69 ( 4 ) I_1027 - I_1032  2013

     View Summary

    The purpose of this experiment is to understand the effect of sand transported from upstream reach of river on both deformation of bed with cohesive sediment and vertical bed structure. In this experiment, the amount of sediment feeding is equal to the amount of equilibrium bed-load transport, and experiment was continued until the deformation of the bed reaches the dynamic equilibrium state. As a result, characteristic vertical structure consisting of "sand layer", "sand-clay mixed layer" and "clay layer" were confirmed on the bed. In addition, it was seen that the existence of waves formed over the surface of cohesive sediment leads such vertical bed structure.

    CiNii

  • EFFECT OF PERMEABILITY AND ADHESIVENESS OF MATERIALS ON CHANNEL NETWORK CAUSED BY SLOPE EROSION

    SEKINE Masato, TANAKA Shoma, TADA Atsushi

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   69 ( 4 ) I_1021 - I_1026  2013

     View Summary

    In this study, series of experiments were conducted in order to investigate the effect of permeability of sediment on slope erosion by artificial rainfall. In this study, the slope was mainly composed of sand whose grain size was different in each case. In addition to such experiments, another investigation was carried out to find out the effect of adhesiveness on the erosion of slope which contains some amount of clay. As a result, it was found that overland flow affects surface erosion, and therefore the slope permeability governs the slope erosion considerably. And it was also confirmed that adhesiveness affects channel network formation due to the surface erosion considerably.

    CiNii

  • NUMERICAL SIMULATION OF INUNDATION IN UNDERGROUND SPACE AND EVACUATION MOVEMENT OF PERSONS FROM IT

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   69 ( 1 ) 30 - 43  2013

     View Summary

    Numerical simulation of inundation in actual underground space in Tokyo was conducted. Urban inundation around the space was also computed simultaneously. Characteristic of the inundation process in the space was made clear as a result of this investigation. Evacuation movement of persons from the space was also studied by using the newly invented numerical model. An evacuation route from this space was successfully found and recommended in this study. It was confirmed that the guide for evacuation was effective to make the persons evacuate orderly and safely. The announcement for the persons there to be urged toward the evacuation is also effective so that the evacuation can complete more rapidly. But the special consideration must be needed about the timing not to make the persons be in panic.

    CiNii

  • Static equilibrium state of river bed composed of three grain size groups of sediment

    Masato SEKINE, Yuki HIRAMATSU, Hiromasa MIKUNI

    Journal of Hydroscience and Hydraulic Engineering   30 ( 2 ) 65 - 75  2012

  • RECENT PROGRESS OF SEDIMENT TRANSPORT RESEARCH AND PREDICTION OF BED DEFORMATION

      67 ( 4 ) II_5 - II_8  2012

  • NUMERICAL PREDICTION TECHNIQUE FOR REAL-TIME FORECAST OF RAIN AND INUNDATION IN URBAN AREA

    SEKINE Masato, SAKURAI Yasuhiro, SATO Takamitsu, TANAKA Sou, FURUICHI Nobumichi, SATO Hirotaka, WADA Yuki

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   68 ( 4 ) I_991 - I_996  2012

     View Summary

    Recently, we often experience a localized torrential rain whose intensity is much larger than the design intensity for drainage network systerm. In such a case, severe damage of inundation is expected especially in urban area. In order to reduce the magnitude of damage, the information obtained by numerical simulation is so effective. Recently, the authors have started the attempt for a real-time forecast of inundation as well as the localized torrential rain. In this paper, two numerical prediction techniques in each field were summarized. Numerical simulation of inundation was newly attempted by using the observed mesh-data of rain, and the discussion about the results of prediction was also conducted.

    CiNii

  • STATIC STABLE STRUCTURE AND HIDING EFFECT OF RIVER BED WITH THREE GRAIN SIZE GROUPS OF SEDIMENT

    SEKINE Masato, HIRAMATSU Yuuki, MIKUNI Hiromasa, KADOI Yuki

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   68 ( 4 ) I_931 - I_936  2012

     View Summary

    The main purpose of this study is to understand the evolution process of river bed in case that the sediment size distribution is extremely wide. In this fundamental experimental study, the bed is composed of three groups of sediment, and one of the grain size is completely different from each other. One is L-particle which cannot move at all in the stream, and constitutes a bed frame. And M-particle or S-particle exists in the space surrounded by L-particles, and moves as bed load or suspended load, respectively. Hiding effect of L-particle on M and S-particles was evaluated, and the vertical structure of bed was also made clear in the evolution process toward a static equilibrium state. In addition to these, it was found that the arrangement of L-particle cannot affect the state of equilibrium state.

    CiNii

  • NUMERICAL SIMULATION OF INUNDATION IN THE REGION OF DENSE RESIDENTIAL AREA DUE TO A TORRENTIAL RAIN

    SEKINE Masato, WADA Yuki, SATO Hirotaka

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   68 ( 4 ) I_997 - I_1002  2012

     View Summary

    In order to understand the state of expected inundation in urban area due to a localized torrential rain, a numerical simulation technique can be extremely useful tool. The first author has kept conducting such a research work, and has developed his own technique. In this study, the effect of runoff process from a garden area in residential area to a road (and vice versa) was considered numerically, and the new submodel of it was added to the original model. And it was applied to the event which occured in the basin of the Myosyoji River in 2005. It was confirmed that the model works fairly well. As a result of this study, it was concluded that the effect of the above process was not negligible in this kind of simulation.

    CiNii

  • 局地的な集中豪雨による浸水被害とその軽減対策

    関根 正人

    下水道協会誌   48 ( 584 ) 4 - 6  2011.06

    CiNii

  • Numerical simulation of micro-scale alluvial fan formation

    Masato SEKINE, Motoki OGASAWARA

    Proceedings of the 7th IAHR Syposium on River, Coastal and Estuarine Morphodynamics (RCEM2011)    2011

  • Effects of vegetation root and leaf on slope erosin caused by a heavy rainfall

    Masato SEKINE, Kodai NABESHIMA

    Journal of Hydroscience and Hydraulic Engineering   29 ( 2 ) 17 - 28  2011

  • NUMERICAL SIMULATION OF EVACUATION MOVEMENT IN COMPOUND UNDERGROUND SPACE

    SEKINE Masato, OHNO Ryoma

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   67 ( 4 ) I_961 - I_966  2011

     View Summary

    Evacuation movement of persons from an inundated underground space was investigated in this study. Numerical simulation was conducted under the two conditions; (1) the persons were guided to evacuate in a recommended manner or (2) they escaped through the nearest stairs without guide. Simulation was also conducted in order to make clear the effect of evacuation announcement. It was confirmed that the guide was effective to make an orderly and safe evacuation movement. And the announcement was also effective to make persons escape more rapidly to a ground level in case that it was made at just the right time. This kind of computation must be needed before we make a plan of the announcement.

    CiNii

  • NUMERICAL ANALYSIS OF INUNDATION IN THE REGION OF DOWNTOWN TOKYO WITH RESIDENCE AREA

    SEKINE Masato

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   67 ( 2 ) 70 - 85  2011

     View Summary

    Recently, we often experience a localized torrential rain whose intensity exceeds much beyond the designed magnitude for both a drainage system and an urban river in Tokyo. On September 4-5, 2005, such an extremely heavy rainfall caused the inundation damage in the Myosyoji River basin. And also on August 5, 2008,five workers who worked in a trunk drainage pipe drowned because of the sudden concentration of rainwater in it in Zoshigaya area, Toshima Ward. In this study, numerical simulation model was developed in order to investigate how the rainwater can be removed by both a drainage system and an urban river in these areas during such a rainfall event.The validity of the model was verified by comparing the numerical results and the observed data. As a result of this study, the expanding process of inundation in each region explained above was made clear for some extent hydraulically.

    DOI CiNii

  • EROSION RATE OF COHESIVE SEDIMENT WITH DIFFERENT CLAY-CONTENT-RATIO

    SEKINE Masato, SHIRAKAWA Takeshi, OKA Yukihiro

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   67 ( 4 ) I_745 - I_750  2011

     View Summary

    Erosion rate formula of cohesive sediment had been derived by the first author, but the there was very few information about it in the range that clay-content-ratio Rcc was less than 0.3. A series of erosion experiments were conducted in order to understand the effect of Rcc on the erosion rate. As a result, it was confirmed that the formula was valid in the range of Rcc between 0.1 and 1.0. The influence of watercontent-ratio on the test sample was discussed on the basis of experimental results. A deformation process and a stable profile of cohesive straight channel with a different value of Rcc were also investigated in order to understand the erosion process of cohesive sediment from a different point of view.

    CiNii

  • EXPERIMENTAL STUDY ON THE STATIC EQUILIBRIUM STATE OF RIVERBED CONSISTING OF THREE GRAIN-SIZE GROUPS

    SEKINE Masato, MIKUNI Hiromasa, HIRAMATSU Yuuki

    PROCEEDINGS OF THE JAPANESE CONFERENCE ON HYDRAULICS   67 ( 4 ) I_733 - I_738  2011

     View Summary

    The purpose of this study is to understand the evolution process of river bed whose sediment size distribution is extremely wide. As a first stage of such study, movable bed experiments were conducted under the condition that the bed was composed of three different grain-sizes of sediment whose diameters take a different order of magnitude. One represents a group of larger size of sediment which can not move at all, and the others are in the group of medium or finer one which moves as a bed-load or a suspended load. In the process toward the stable state of bed, it was found that a typical vertical sorting occurred, and the characteristics of the bed structure were discussed on the basis of experimental results.

    CiNii

  • 複雑な構造をもつ地下鉄駅構内の浸水過程と避難誘導に関する数値解析

    関根正人

    水工学論文集   54   907 - 912  2010.02

    CiNii

  • 雑司ヶ谷幹線下水道における水難事故に関する数値解析

    関根正人, 青野雅士, 風間大彰

    水工学論文集   54   901 - 906  2010.02

  • 植生の根系と葉系が降雨に斜面浸食過程に及ぼす影響

    関根正人, 鍋島康大

    水工学論文集   54   655 - 660  2010.02

  • Gravel-Silt-Packed Bed Model and Its Application to the River Channel Deformation with Vegetation

    Masato SEKINE

    International Journal of Erosion Control Engineering   3 ( 2 ) 117 - 125  2010

     View Summary

    Channel deformation process of a gravel-bed river with vegetation zone was investigated in the present study. The channel is assumed to be constituted by gravel-silt mixture. When we simulate this deformation process, the evaluation of erosion rate of silt from gravel-bed is important. The formula by Ashida and Fujita [1986] is only the applicable one. In this study, a "gravel-silt-packed bed model" was newly invented and introduced in order to make the computation effectively with the above mentioned formula. The model enables us to predict a temporal variation of sediment composition in bed as well as the bed elevation reasonably. In this paper, the model was applied to investigate the effect of both a zone of vegetation and a silt erosion and deposition on the channel deformation. As a result, it was confirmed that a depositional terrace like landform formed just inside the vegetation zone around a water margin, which was observed and reported by Fujita et al. [1996].

    DOI CiNii

  • NUMERICAL ANALYSIS OF ALLUVIAL FAN FORMATION ON A PERMEABLE PLAIN

    OGASAWARA Motoki, SEKINE Masato

    Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering)   66 ( 2 ) 167 - 178  2010

     View Summary

    The formation process of depositional landforms on a 2-D permeable plain was studied numerically. In this paper, such landforms are called a micro-scale alluvial fan. The purpose of this study is to develop a numerical model which enables us to simulate this formation process. To understand the formation mechanism more precisely is also the purpose of it. The Slope collapse model was applied in order that the local slope angle does not to exceed the angle of repose. And the modified version of bed load transport function was introduced so as to consider the gravity effect associated with the slope angle in longitudinal and lateral directions. Water flow was computed on the basis of both the 2-D shallow water equations for surface flow and the 3-D Richards' equation for subsurface flow. Comparison was made between a computed result and that of the experiment by Sekine et al. (1998). As a result, it was verified that the numerical model works fairly well, and the formation process of micro-scale alluvial fan can be simulated reasonably. The process is closely related to the channel deformation process, that is, channel migration, disappearance of the channel, and a new channel formation.

    CiNii

  • Numerical analysis of alluvial fan formation on a permeable plain

    Motoki Ogasawara, Masato SEKINE

    Advances in Hydro-science and Hydraulic Engineerin, IAHR   Volume VIII   387 - 388  2009.09

  • 2005年集中豪雨により発生した妙正寺川流域の氾濫被害に関する数値解析

    関根正人, 風間大彰, 青野雅士

    土木学会水工学論文集   53   811 - 816  2009.02

  • Numerical simulation of urban inundation due to a localized torrential rain in the Myosyoji River Basin

    Masato Sekine, Hiroaki Kazama, Masashi Aono

    Proc. of 8th International Conference on Urban Drainage Modeling    2009

  • Numerical simulation of inundation in underground space in highly urbanized area in Tokyo

    Masato Sekine, Jun Nakamura

    Proc. of 8th International Conference on Urban Drainage Modeling    2009

  • EROSION RATE FORMULA OF COHESIVE SEDIMENT

    NISHIMORI Ken-ichiro, SEKINE Masato

    Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering)   Vol.65 ( No.2 ) 127 - 140  2009

     View Summary

    Main purpose of this study is to evaluate the erosion rate of cohesive sediment. More than 100 experiments were conducted in a closed conduit, and the test sample was the mixture of kaolin, silica sand, the composition of which was a variable. It was found from this study that a frictional velocity of flow, a water temperature and a water content ratio are the most dominant factors, and the amount of sand or gravel and its grain size contained in the sample, on the other hand, are independent of the erosion rate approximately. Erosion rate formula was derived in this study on the basis of the experimental results. Erosion process was also investigated qualitatively through an image processing.

    DOI CiNii

  • Inundation process of underground space in highly urbanized area

    Masato SEKINE, Nobuhisa Kawakami, Kazuhiro Motoyama

    Advances in Hydro-science and Hydraulic Engineering   Volume VIII   2200 - 2208  2008.09

  • Formation process of depositional landforms on a permeable flat plain

    Motoki Ogasawara, Masato SEKINE

    Journal of Hydroscience and Hydraulic Engineering, JSCE   26 ( 1 ) 29 - 38  2008.05

    CiNii

  • Experiments on the erosion rate of cohesive sediment using a movable erosion test apparatus

    Ken-ichiro Nishimori, Masato SEKINE, Takayoshi Higuchi

    Journal of Hydroscience and Hydraulic Engineering, JSCE   26 ( 1 ) 39 - 46  2008.05

    CiNii

  • 大河川からの越水を想定した東京東部低平地の外水氾濫解析

    関根正人, 秋本健輔

    土木学会水工学論文集   52   865 - 870  2008.02

  • 地下空間浸水時の避難誘導に関する数値解析

    関根正人, 本山量啓

    土木学会水工学論文集   52   847 - 852  2008.02

  • 植生の根系が斜面浸食に及ぼす影響に関する実験的研究

    関根正人, 大前謙友, 松島貴之

    土木学会水工学論文集   52   559 - 564  2008.02

  • 実河川に堆積した粘着性土の浸食速度評価に関する実験的研究

    西森研一郎, 関根正人, 樋口敬芳, 赤木俊雄

    土木学会水工学論文集   52   541 - 546  2008.02

  • Formation process of depositional landform over a permeable flat plain

    M. Ogasawara, M. Sekine

    RIVER, COASTAL AND ESTUARINE MORPHODYNAMICS: RCEM 2007, VOLS 1 AND 2     885 - 890  2008  [Refereed]

     View Summary

    The formation process of depositional landform over a one-dimensional permeable flat plain was investigated numerically in this paper. In such a process, a water exchange between a surface flow and a subsurface flow is important to be taken into account. The governing equations of the flows are one-dimensional shallow water equations for surface flow, and two-dimensional Richards' equation for subsurface flow. As a result of this study, the following two processes were confirmed: (a) a front of surface flow migrates a little in the downstream direction due to the loss of surface-flow discharge, and the thickness of the depositional landform increases; (b) the front migrates with relatively high speed due to the recovery of surface-flow discharge, and the depositional landform spread in the downstream direction.

  • Dispersion process of suspended sediment in turbulent shear flow

    M. Sekine

    RIVER, COASTAL AND ESTUARINE MORPHODYNAMICS: RCEM 2007, VOLS 1 AND 2     485 - 490  2008  [Refereed]

     View Summary

    In this study, numerical simulation of suspended sediment transport was conducted on the basis of an equation of motion in mass point system. LES turbulence model was introduced to simulate a coherent structure of turbulent shear flow which is composed of a series of ejection and sweep. The motion of multiple sediment particles were computed in this flow field, and their trajectories were analyzed statistically. And then a diffusion coefficient of sediment was evaluated numerically on the basis of diffusion theory by Taylor (1953). It was found that the diffusion coefficient of sediments approaches to that of turbulence as the sediments continue to move. This result coincides with the assumption of traditional analysis.

  • Erosion rate of cohesive sediment by running water

    Ken-ichiro Nishimori, Masato SEKINE

    Advances in Hydro-science and Hydraulic Engineerin, IAHR   Volume VIII   333 - 334  2008

  • Erosion rate of cohesive sediment by running water

    Masato SEKINE, Ken-ichiro Nishimori

    Proceedings of the 4th International Conference on Scour and Erosion (ICSE-4 Tokyo)     424 - 429  2008

  • 土砂の運動解析を基礎とした浮遊砂の分散過程に関する研究

    関根正人

    土木学会論文集B   Vol.63 No.4 ( 4 ) 311 - 322  2007.11

     View Summary

    In this study, numerical simulation of suspended sediment transport was conducted on the basis of the equation of motion in mass point system. LES turbulence model was introduced to simulate a coherent structure of turbulent shear fow which is composed of a series of ejection and sweep. Several hundred of sediments were traced in such a flow field, and their trajectories were analyzed statistically. Diffusion coefficient of sediment was evaluated numerically on the basis of diffusion theory by G.I. Taylor, and was compared with the value of turbulent diffusion coefficient. As a result, these two coefficients were found to take approximately same value, which coincides with the assumption of traditional analysis.

    DOI CiNii

  • 雨水の浸透・流出課程を考慮に入れた斜面浸食過程に関する数値解析

    小笠原基, 関根正人

    日本流体力学会年会    2007.08

  • 準二次元解析手法を用いた礫床河川の長期河床変動予測

    関根正人, 林将宏

    日本流体力学会年会    2007.08

  • 浸透が卓越する場に形成される堆積地形に関する数値解析

    小笠原基, 関根正人

    土木学会水工学論文集   51   979 - 984  2007.02

     View Summary

    Numerical analysis of the flow, which is established under the effect of interaction between surface flow and subsurface flow, was conducted, together with the analysis of the bed evolution due to a sediment transport in this study. Basic equations of water flow are one-dimensional shallow water equation for surface flow, and two-dimensional Richards equation for subsurface flow. Numerical model was applied to simulate the formation process of depositional landform on one-dimensional permeable bed, which is just like a fl uvial fan.

    DOI CiNii

  • 礫・シルト充填河床モデルを用いた礫河道の準二次元河床変動解析

    関根正人, 林 将宏

    土木学会水工学論文集   51   973 - 978  2007.02

     View Summary

    he knowledge about an actual condition of sediment transport at any local point in river is now needed as basic information before we discuss the preferable state of river system. In this study, semi-2D numerical model was developed to make the long-term prediction of river bed deformation as well as the local sediment sorting be possible. Gravel-silt packed bed model(2005) was included in the developed numerical model, which was applied to Sakawa River, which was a steep gravel bed river in Kanagawa Prefecture. Based on the result of sample calculation, the numerical model was found to work fairy well in terms of qualitative consideration.

    DOI CiNii

  • 簡易試験装置を用いた粘着性土の浸食実験とその試験法に関する研究

    西森研一郎, 関根正人, 樋口敬芳

    土木学会水工学論文集   51   865 - 870  2007.02

     View Summary

    Erosion rate of soft cohesive sediment was investigated experimentally in the present paper. In this study, we developed a movable apparatus of erosion test, which was designed to conduct a field measurement of erosion rate. In order to check the validity and utility of this apparatus, the several series of measurements were carried out outside in large-scale experimental flume. It was verified that the results by this new measuring system has almost same order of accuracy as that by our standard test in laboratory. Effect of water temperature on the erosion rate were also evaluated quantitatively.

    DOI CiNii

  • 浸水時の地下空間からの避難行動に関する数値シミュレーション

    関根正人, 本山量啓

    土木学会水工学論文集   51   547 - 552  2007.02

     View Summary

    Numerical model of evacuation behavior of people from the inundated underground space was investigated in this study. Information about a human behavior was taken into account as much as possible, a walking velocity, for example, was evaluated on the basis of relation between it and the congestion density of crowd. It was considered that the movement of each people was affected by both the movement by others and the approching flow of water on the floor. Numerical simulation was conducted in the relatively large scale model of underground space. It can be concluded that the present model works well and the reasonable simulation of evacuation behavior is possible to be realized.

    DOI CiNii

  • 環境ホルモン物質の河道内貯留に関する基礎的研究

    関根正人, 大内良二

    土木学会水工学論文集   50   1087 - 1092  2006.02

  • 粘土を含有する裸地斜面の降雨による表面浸食過程に関する研究

    関根正人, 長濱正憲, 西森研一郎

    土木学会水工学論文集   50   1045 - 1050  2006.02

  • 地下鉄駅が立体的に接続する地下空間における浸水過程に関する研究

    関根正人, 中村 淳

    土木学会水工学論文集   50   667 - 672  2006.02

  • 地下街を抱える高度に都市化された地域の内水氾濫に関する数値解析

    関根正人, 河上展久

    土木学会論文集   789/II-71   47 - 58  2005.05

  • 鬼怒川における洪水時の流路変動とその数値予測に関する研究

    関根正人, 片桐康博, 小笠原基

    土木学会水工学論文集   49   1015 - 1020  2005.02

     View Summary

    The channel deformation in Kinu River during a flood period was investigated in the present study. Field measurement and film analysis were conducted to quantify the temporal and spatial changes in channel profile in the reach of 54.5-56.5 km from the confluence point to Tone River in the term between 2001 and 2003. Considerable amount of bank erosion and channel shift were observed, and the alternative channel was created just after the final flood during this term. As a result of this analysis, it was found that the magnitude of channel deformation depends on an individual flood discharge and also on the history of the former flood events. Numerical analysis was also conducted to understand more deeply the mechanism of this channel deformation. It was confirmed that the numerical model worked fairly well.

    DOI CiNii

  • 礫・シルト充填河床モデルを用いた植生を伴う流路の変動解析

    関根正人, 矢島英明

    土木学会水工学論文集   49   991 - 996  2005.02

     View Summary

    The channel deformation of gravel-bed river with vegetation zone was investigated in the present study. The channel is assumed to be constituted by a gravel-silt mixture. In order to simulate such a phenomenon, the erosion rate of silt from gravel bed surface is the important factor to be considered. The formulation by Ashida and Fujita (1986) was applied here in the numerical model. Numerical computation was conducted by considering the effect of silt erosion and deposition on the channel deformation. As a result of this, it was confirmed that the depositional configuration like a terrace formed just inside the vegetation zone, which was mentioned by Fujita et al.(1996).

    DOI CiNii

  • 砂礫の運動解析を基礎とした河床波形成過程シミュレーション

    関根正人

    土木学会水工学論文集   49   973 - 978  2005.02

     View Summary

    Numerical simulation of sediment wave formation was conducted in the present study. Saltation model has been extended in order to analyze the entire motion of particle which starts by being picked-up from a bed and ceases its motion by depositing on it. The procedure in which a mutual collision between moving particles can be explained physically was newly invented here to consider the effect of interaction between them. Based on such models, the multi-particle motion can be analyzed simultaneously. In this paper, the gravel bed deformation which is caused by each particle motions was predicted under the same condition of flume experiment.

    DOI CiNii

  • 乾燥・湿潤履歴が粘着性土の浸食速度に及ぼす影響に関する研究

    関根正人, 西森研一郎, 安藤史紘

    土木学会水工学論文集   49   877 - 882  2005.02

     View Summary

    The effect of dry-wet history on the erosion process of cohesive sediment was investigated experimentally in the present study. Detailed discussion on the mechanism of this process was conducted here on the basis of enormous number of experimental data. In this experiment, the test sample keeps under dry or wet conditions every 6 hours, and erosion test was conducted just after each period. It wasfound that this process can be classified into two parts in their mechanisms according to the total period of this history. The erosion rate of test sample which experienced this history more than one day keeps almost constant value which agrees well with the predicted value of the erosion rate formula.

    DOI CiNii

  • 都市域における内水氾濫と地下鉄に接続する地下空間の浸水に関する数値解析

    関根正人, 河上展久

    土木学会水工学論文集   49   595 - 600  2005.02

     View Summary

    Inundation process in underground space which connecting to a subway station in urban area was studied numerically. Actual data sets of (1) road network, (2) drainage network and (3) underground space in the area around Shibuya Station were considered here, and a simplified numerical model was constructed. Based on the results of numerical computation, the characteristics and the weak points of the drainage system in this area were quantitatively understood. It was revealed that (1) the local area whose ground elevation is relatively lower and (2) the undergournd space are the possible area where extensive damage will result if there happenes to be the rainfall whose intensity exceeds the designed one.

    DOI CiNii

  • Numerical simulation of braided stream formation on the basis of slope-collapse model

    Masato SEKINE

    Journal of Hydroscience and Hydraulic Engineering, JSCE   22 ( 2 ) 1 - 10  2004.11

    CiNii

  • Erosion process of cohesive sediment and erosion rate formula

    Masato SEKINE

    Journal of Hydroscience and Hydraulic Engineering, JSCE   22 ( 1 ) 63 - 70  2004.05

    CiNii

  • 降雨により生じる裸地斜面の表面浸食とこれに伴う土砂流出に関する数値解析

    関根正人, 菱沼志朗

    水工学論文集 / 土木学会   48   961 - 966  2004.02

  • 植生群落を伴う河道の流路変動予測に関する研究

    関根正人, 矢島英明

    水工学論文集 / 土木学会   48   1045 - 1050  2004.02

  • 網状流路の形成過程における河床と河岸の相互作用

    関根正人, 小笠原基

    水工学論文集 / 土木学会   48   1039 - 1044  2004.02

  • 粘着性土の浸食速度に与える乾燥湿潤履歴の影響

    関根正人, 西森研一郎, 安藤史紘

    水工学論文集 / 土木学会   48   937 - 942  2004.02

  • Numerical Simulation of Braided Stream Formation

    Masato SEKINE

    IAHR Congress Proceedings 3rd IAHR Symposium on River, Coastal and Estuarine Morphodynamics    2003.09

  • 鬼怒川網状区間を対象とした洪水期間中の流路変動とその予測に関する研究

    関根正人, 片桐康博, 矢島英明

    河川技術論文集 / 土木学会   9   323 - 328  2003.06

  • 集中豪雨による都市域の内水氾濫と地下街浸水の被害軽減に関する研究

    関根正人, 河上展久

    河川技術論文集 / 土木学会   9   149 - 154  2003.06

    CiNii

  • 都市における内水氾濫と地下街浸水の被害予測に関わる数値解析

    関根正人, 河上展久

    土木学会水工学論文集   47   889 - 894  2003.02

    CiNii

  • 斜面崩落モデルを用いた網状流路の形成過程シミュレーション

    関根正人

    土木学会水工学論文集   47   637 - 642  2003.02

    CiNii

  • 粘着性土の浸食進行過程と浸食速度式に関する考察

    関根正人, 西森研一郎, 藤尾健太, 片桐康博

    土木学会水工学論文集   47   541 - 546  2003.02

    CiNii

  • 降雨による斜面浸食過程に関する数値解析

    関根正人, 小野 了

    土木学会水工学論文集   46   647 - 652  2002.02

  • 粘着性土の浸食速度に及ぼす粘着力の影響

    関根正人, 藤尾健太, 片桐康博, 西森研一郎

    土木学会水工学論文集   46   641 - 646  2002.02

    CiNii

  • 土砂粒子の運動の解析を基礎とした河床波の形成過程シミュレーションの試み

    関根正人

    土木学会論文集   692/II-57   85 - 92  2001.11

  • 都市地下空間の浸水被害シミュレーションの試み-新宿地下街を対象として-

    関根正人, 前川桂恵三

    土木学会河川技術論文集   7   161 - 166  2001.06

    CiNii

  • 粘着性土の浸食速度予測に向けた実験的研究

    関根正人, 飯塚暢明, 藤尾健太

    土木学会水工学論文集   45   667 - 672  2001.02

    CiNii

▼display all

Books and Other Publications

  • 移動床流れの水理学

    関根正人

    共立出版  2005.02 ISBN: 4320074165

  • 砂防用語集

    砂防学会編

    山海堂  2004.12 ISBN: 4381015908

Awards

  • 早稲田大学ティーチングアワード総長賞

    2018.02  

  • 土木学会水工学論文賞

    2016.03  

  • 土木学会水工学論文賞

    2015.03  

  • 土木学会水工学論文賞

    2004.03  

Research Projects

  • 粘土から大礫までの材料からなる河床上の流砂モデルの再構築と数値予測手法の開発

    Project Year :

    2020.04
    -
    2023.03
     

     View Summary

    本研究で取り組むのは,石礫・礫・砂・シルトならびに粘土からなる河床上で生じる流砂現象であり,従来の流砂理論の枠組みを超えたところに位置する二つの重要な現象を取り上げ,条件を制御した一連の移動床水理実験を通じてその本質を明らかにすることを目指します.具体的には,大きな粒径の石礫あるいは礫が,より小さな砂礫・シルトに及ぼす遮へい効果を表す評価式を誘導し,その妥当性を検証します.また,粘土からなる河床が掃流砂の作用を受けて砂礫河床へと遷移するメカニズムを解明していきます.さらに,これら二つの流砂現象を数値予測する手法を新たに開発し,実河川への適用を図ります

  • 都市浸水リスクのリアルタイム予測・管理制御

    科学技術振興機構 (JST)  未来社会創造事業

    Project Year :

    2017.11
    -
    2020.03
     

  • Mechanism of river embankment collapse by overflow of river and water seepage

    Project Year :

    2016.04
    -
    2019.03
     

     View Summary

    It was clarified experimentally that a noticeable difference appeared in the process of collapse according to the ratio of "gravel, sand, clay" constituting the embankment, and the elucidation of the mechanism was revealed considerably. When clay is contained enough to fill the gap of the gravel, erosion is suppressed because of the erosion resistance of clay, and the embankment becomes much more tenacious and difficult to collapse. In addition to clay and sand, when gravel is contained in a certain ratio, the effect of the interlocking between the gravel particles becomes noticeable, and the embankment collapse is difficult to cause. If clay is contained more than a certain ratio, the embankment becomes easier to deform. If the content ratio of the gravel is too large, the permeability of the entire material is increased and collapse by penetration. It is believed that the best ratio of mixture among "gravel, sand, and clay" exists for a tenacious embankment

  • 越水ならびに浸透による河川堤防決壊のメカニズムに関する研究

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(基盤研究(C))

    Project Year :

    2016.04
    -
    2019.03
     

  • Study on the erosion mechanism of the soft rock by the flow of water and its application to the actual river

    Project Year :

    2012.04
    -
    2015.03
     

     View Summary

    The cohesive materials which contained clay and had full compaction came to be exposed on actual riverbed, e.g., the Kinugawa River. Due to this, it was reported that the erosion of an unprecedented scale occurred. In this study, a series of fundamental movable bed experiments were conducted to elucidate the mechanism of such cohesive sediment erosion. As a result, it was made clear what kind of change appeared for the erosion of the clay riverbed by sand and gravel which had been transported as bed load from upstream reach of river. In addition, the numerical prediction technique was newly developed. It enables us to predict a deformation of the bed or slope which contained clay. It was applied to a surface erosion phenomenon of the bare slope. And another flume experiments were conducted in order to verify validity of this technique. As a result, it was verified that the formation process of channel network on a slope can be predicted precisely by this technique

  • 水流による軟岩の浸食機構の解明とその実河川への応用に関する研究

    科学研究費助成事業(早稲田大学)  科学研究費助成事業(基盤研究(C))

    Project Year :

    2012
    -
    2014
     

     View Summary

    近年,実河川の河床に固結化した粘着性土(あるいは堆積軟岩)が露出するようになりました.本研究では,このような特異な河床材料が水流ならびに流送砂礫の作用によって浸食されていくメカニズムを探るとともに,その浸食速度自体を推定可能とすることを目的としています.このため,2013年度には次のような検討を行いました.
    堆積軟岩の浸食が顕著になってきた鬼怒川の実態を把握するため,下館河川事務所とともに現地調査を行いました.また,現地材料を不攪乱状態で採取し,これを供試体とした土質試験を行い,材料の土質力学特性について検討しました.次に,このような材料が水流ならびに流送砂礫の影響を受けて浸食されていくメカニズムを探るための移動床水理実験を行いました.この実験時には,上流側から砂礫を供給しながら通水を行うことが必要になります.そのため,前年度まで用いてきた大型の開水路における実験に加えて,連続給砂が可能なアクリル性矩形断面閉水路を新たに設計・製作し,この水路において給砂量を制御しながらの一連の実験を行いました.
    2013年度までの実験的な検討は,粘土として一般的なカオリンを対象としたものに止まっていますが,水流のみによる浸食現象とは明らかに異なる興味深い結果が得られました.たとえば,単位時間当たりに浸食される粘土の体積 (これを「浸食速度」と呼ぶ) は,供給される砂礫の量(給砂量)の大小の影響を顕著に受け,給砂量がある値の時に極大値をとるような特性を有するというものです.この点についてはこれまでにも示唆されてきましたが,一連の基礎的な実験を通じてこれが明確に説明されたことは今後に向けて価値あるものと考えております.また,このような実験と並行して,粘着性土からなる裸地斜面の表面浸食に関わる実験的検討もあわせて行ってほか,この現象を数値解析により予測する手法の開発も進めてきました.

  • Study on the erosion mechanism of the soft rock by the flow of water and its application to the actual river

    Project Year :

    2012
    -
    2014
     

     View Summary

    The cohesive materials which contained clay and had full compaction came to be exposed on actual riverbed, e.g., the Kinugawa River. Due to this, it was reported that the erosion of an unprecedented scale occurred. In this study, a series of fundamental movable bed experiments were conducted to elucidate the mechanism of such cohesive sediment erosion. As a result, it was made clear what kind of change appeared for the erosion of the clay riverbed by sand and gravel which had been transported as bed load from upstream reach of river. In addition, the numerical prediction technique was newly developed. It enables us to predict a deformation of the bed or slope which contained clay. It was applied to a surface erosion phenomenon of the bare slope. And another flume experiments were conducted in order to verify validity of this technique. As a result, it was verified that the formation process of channel network on a slope can be predicted precisely by this technique

  • GOVERNING EQUATIONS OF SOLID-LIQUID TWO PHASE FLOW AND THEIR APPLICATIONS

     View Summary

    Three types of models, i.e.one fluid model, two fluid model and particle-fluid model, are generally applied to investigate the characteristics of two phase flow. In each the careful consideration on the structures of governing equations and the constitutive relations employed should be needed. Essential point to be discussed in this study is how the effects of interactions between two phases are taken into account in these basic equations

  • Mechanics of Stable Straight Channel or Braided Channel Formation

     View Summary

    The process in which a straight channel reaches a stable equilibrium state was investigated. The process is classified into a following two categories ; (1) channel widening process due to a bank erosion in case that the initial channel width is larger than the stable one, (2) channel narrowing process due to a sediment deposition around a water margin which is caused by the unsteadiness of water discharge. Such two processes were reported through the field investigations by the researchers in Public Works Research Institute, Ministry of Construction, Japan. In this study, the processes were simulated in an experimental flume. Numerical simulation model was also constructed to understand the process itself.The process in which a braided channel network forms was also investigated. Channel network formation on a bare slope as well as a braided river formation in a flume was studied experimentally with a focus attention on the similarity between these two processes. The mechanism was understood. For example, subsurface flow plays an important role in such formation. Some other interesting information was also obtained. Besides the experimental investigation, numerical model was developed in some limited conditions. This will be extended in more sophisticated version in future.The mechanisms of the above two processes were made clear as the author expected in the initial plan

  • Research on Free Meandering and Channel Width Formation in Channels with Mixture Grain Size Bed Material

     View Summary

    Fine sand deposition on a floodplain during the Abukuma River flood in 1998 is studied both observationally and theoretically. It is found from the observation that most of the deposition consists of fine sand of about 0.1 mm in diameter, which is commonly refer to washload that is not included in bed material. The observed data shows that the deposition is maximized around 10 m inside of the floodplain along the boundary between the main channel and the floodplain. This phenomenon is found to be well-explained by the theory of suspended sediment transport. The predicted value of the magnitude of the deposition agrees well with the observed value with the use of suspended sediment concentration obtained in another observation.A numerical model is proposed to investigate free meandering of river. Flow field, bed deformation, bank erosion and channel migration are calculated numerically with a general non-orthogonal coordinate system which can be applied to moving boundary conditions. Flow field is calculated from two dimensional momentum equations and continuity equation. Bed deformation is calculated from continuity equation of bed load transport. Bank erosion and deposition is estimated from critical slope of bank material and emergence of bed due to the bed deposition. Time dependent change of channel geometry is calculated with an iteration process of these procedures. Calculated results are favorably compared with experimental results with movable bed and bank, and thus the accuracy of new model is verified

  • Study on the erosion mechanism of cohesive sediment and its application to the phenomenon in rivers

     View Summary

    Erosion process of soft cohesive sediment which deposited naturally on a river bed is the objective of this study. Extensive series of experiments, the condition of which were set systematically, were conducted to evaluate the erosion rate by running water in a closed conduit. The test sample was the mixture of silica sand, clay and water, the composition of which was set to be variable. The main factors which govern this process were found to be the clay content ratio, the water content ratio, a frictional velocity of flow, a water temperature, the size of silica sand and so on. The effects of these parameters on the erosion rate were evaluated quantitatively. The correlation between the erosion rate and the adhesive strength of the sediment was also investigated by conducting the soil mechanical test. Erosion rate formula was also derived on the basis of experimental results. The attempt was also conducted to test the applicability of the formula to the sediment deposited on the real river

  • Exoerimental study on erosion rate of cohesive sediment and the attempt toward direct measurement of it in revers.

     View Summary

    The erosion process of soft cohesive sediments, which were deposited naturally on a river bed, is investigated in this study. Extensive series of experiments, conditions of which were set systematically, were conducted to evaluate the erosion rates by running water in a closed conduit. Test samples consisted of a mixture of silica sand, clay and water, the composition of which was set to be a variable. The main factors which govern this process were found be the clay content ratio (the weight ratio of clay to the total sediment), the water content ratio (the weight ratio of water to the clay), and a frictional velocity of flow, a water temperature, the size of silica sand and the dry-wet history. The effects of these parameters on the erosion rate were evaluated quantitatively. The erosion rate formula was also derived on the basis of experimental results. Also, the mechanism of this process was examined and made clear to a certain extent. In addition to these fundamental studies, the portable measuring system of erosion rate in a real river was developed, and a series of measurement was also conducted confirm the validity of this erosion test

  • Evaluation technique for erosion rate of cohesive sediment and its application to the geomorphological

     View Summary

    Erosion process of cohesive sediment was investigated experimentally in this study. Fundamental studies had been already conducted in the experimental flume to evaluate the erosion rate of uniform cohesive sediment. In this study, we developed a movable apparatus of erosion test, which was designed to conduct a field measurement of erosion rate of naturally deposited cohesive sediment. We also established the experimental techniques for such a measurement. Several series of measurements were conducted in large-scale open-air experimental flume in order to check the validity and utility of this apparatus. It was verified that the results had almost same order of accuracy as that by our standard test in laboratory. This is one of the main achievements of this study.The effect of cohesiveness of sediment on the erosion process of bare-slope was also investigated here. This is the second part of this study. Experiments were conducted to investigate the geomorphological change in model bare slope, which was constituted by cohesive sediment, due to an artificial rainfall. Before doing that, the information about the experimental technique of erosion test of cohesive sediment by us was instructive. Clay content ratio is only the parameter to be changed in this series of experiments. It was seen that the main channel which formed on the slope grew narrower and deeper as the clay content ratio increased. Vertical erosion on the bed was found to be more dominant than the lateral bank erosion. It was also understood that the erosion process and the geometry of channel network in case of cohesive bare slope have different characteristics than those of cohesionless slope

  • Inundation risk in highly urbanized area and the strategy of evacuation from an underground space

  • Deformation process of river channel with cohesive sediment and the stable cross-section in the equilibrium state.

     View Summary

    Experimental investigation was conducted in order to clarify the effect of cohesive sediment on stable channel geometry in dynamic equilibrium state. Comparing the result with the one in case of sand only, the bank erosion is less remarkable in case that the bed is composed of sand and clay mixture. It should be noted that sediment sorting occurs in the river bed because of the deposition of sand only. And another series of experiments were also conducted in this study on the equilibrium state of bed with an extremely wide range of sediment size distribution. Hiding effect of the larger stone on gravel and sand was made clears quantitatively

▼display all

Presentations

  • 粘土・砂・礫からなる模擬堤防の越流決壊プロセス

    関根 正人, 松浦 泰地, 菅 俊貴, 佐藤 耕介

    土木学会第74回年次学術講演会  (高松市)  土木学会

    Presentation date: 2019.09

  • 掃流砂が粘土河床の変動プロセスに及ぼす影響

    関根 正人, 吉川 文崇, 石原 駿, 芦澤 穂波, 佐藤 裕

    土木学会第74回年次学術講演会  (高松市)  土木学会

    Presentation date: 2019.09

  • 粒度幅の大きな材料からなる河床近傍で生じる土砂粒子間の遮蔽効果

    平松 裕基, 本合 弘樹, 関根 正人

    土木学会第74回年次学術講演会  (高松市)  土木学会

    Presentation date: 2019.09

  • 鶴見川流域を含む横浜市東部エリアにおける浸水リスク評価

    馬場 航

    土木学会第74回年次学術講演会  (高松市)  土木学会

    Presentation date: 2019.09

  • 高度に都市化された川崎南部を対象とした浸水リスクの評価

    吉野 萌

    土木学会第74回年次学術講演会  (高松市)  土木学会

    Presentation date: 2019.09

  • 掃流砂として移動する砂礫の粒度分布の違いが混合砂礫河床の鉛直構造に与える影響

    本合弘樹

    土木学会第73回年次学術講演会  (北海道) 

    Presentation date: 2018.08

  • 礫を含有する模擬堤防の越流決壊プロセス

    菅俊貴

    土木学会第73回年次学術講演会  (北海道) 

    Presentation date: 2018.08

  • 掃流砂礫による粘土河床の浸食促進・抑制効果

    吉川文崇

    土木学会第73回年次学術講演会  (北海道) 

    Presentation date: 2018.08

  • 掃流砂の作用により生じる一様湾曲流路内の粘土河床の変動

    佐藤裕

    土木学会第73回年次学術講演会  (北海道) 

    Presentation date: 2018.08

  • 粘土河床上に配置した模擬巨石による河床変動と砂礫の捕捉効果

    芦澤穂波

    土木学会第73回年次学術講演会  (北海道) 

    Presentation date: 2018.08

  • 東京都臨海部を対象とした高潮時の浸水リスク評価

    小方公美子

    土木学会第73回年次学術講演会  (北海道) 

    Presentation date: 2018.08

  • 横浜市東部における豪雨時の浸水危険度評価

    竹村尚樹

    土木学会第73回年次学術講演会  (北海道) 

    Presentation date: 2018.08

  • 荒川堤防決壊時の東京東部低平地における住民避難

    古川侑里

    土木学会第73回年次学術講演会  (北海道) 

    Presentation date: 2018.08

  • 骨格が大礫により構成された河床に生じる鉛直分級とその構造

    本合弘樹

    砂防学会第67回研究発表会  (鳥取) 

    Presentation date: 2018.05

  • 掃流砂の移動に伴う河道湾曲部の粘土河床の浸食現象

    佐藤裕

    土木学会第72回年次学術講演会  (福岡) 

    Presentation date: 2017.09

  • 掃流砂の移動に伴い生じる粘土河床の浸食促進・抑制効果

    芦澤穂波

    土木学会第72回年次学術講演会  (福岡) 

    Presentation date: 2017.09

  • 堤防の土質構造の違いが決壊プロセスに及ぼす影響

    佐藤耕介

    土木学会第72回年次学術講演会  (福岡) 

    Presentation date: 2017.09

  • 掃流砂礫の粒度分布の違いが粒径幅の大きな河床の鉛直構造に及ぼす影響

    中川裕貴

    土木学会第72回年次学術講演会  (福岡) 

    Presentation date: 2017.09

  • 荒川と江戸川にはさまれた東京東部低平地の豪雨時浸水リスクの評価

    小方公美子

    土木学会第72回年次学術講演会  (福岡) 

    Presentation date: 2017.09

  • 東京都23区を対象とした都市浸水の再現計算とその精度検証

    中森奈波

    土木学会第72回年次学術講演会  (福岡) 

    Presentation date: 2017.09

  • 荒川堤防決壊に伴う大規模浸水と地下鉄トンネル内の浸水の拡大プロセス

    児玉香織

    土木学会第72回年次学術講演会  (福岡) 

    Presentation date: 2017.09

  • 荒川決壊を想定した東京東部低平地の大規模浸水プロセスに関する数値予測

    小林香野

    土木学会第71回年次学術講演会  (宮城) 

    Presentation date: 2016.09

  • 森ヶ崎下水道処理区を対象とした豪雨時の浸水の数値予測とこれによる危険度評価

    斎藤涼太

    土木学会第71回年次学術講演会  (宮城) 

    Presentation date: 2016.09

  • 石神井川流域における下水道への雨水集中プロセスと内水氾濫

    神山宙大

    土木学会第71回年次学術講演会  (宮城) 

    Presentation date: 2016.09

  • 初期条件の違いが粒度幅の極端に広い河床の鉛直構造に与える影響

    中川裕貴

    土木学会第71回年次学術講演会  (宮城) 

    Presentation date: 2016.09

  • 砂質土からなる堤防の越流破堤に関わる実験的検討

    鈴木昌宏

    土木学会第71回年次学術講演会  (宮城) 

    Presentation date: 2016.09

  • 掃流砂として移動する砂礫が粘土河床の浸食に及ぼす影響と河床の鉛直構造

    池田憲昭

    土木学会第71回年次学術講演会  (宮城) 

    Presentation date: 2016.09

  • 供給される砂礫の混合比率が粒度幅の広い河床の鉛直構造に及ぼす影響

    中川裕貴

    砂防学会第65回研究発表会  (富山) 

    Presentation date: 2016.05

  • 石神井川を対象とした豪雨時の浸水数値予測

    小林香野

    土木学会第70回年次学術講演会  (岡山) 

    Presentation date: 2015.09

  • XRAINによる降雨データを用いた東京都心部のリアルタイム浸水予報に向けた試み

    関根貴広

    土木学会第70回年次学術講演会  (岡山) 

    Presentation date: 2015.09

  • 粘土河床の浸食プロセスとこれに及ぼす砂礫の影響

    高野大貴

    土木学会第70回年次学術講演会  (岡山) 

    Presentation date: 2015.09

  • 隣接した粘土層の存在が砂斜面の表面浸食に及ぼす影響

    佐野正太

    土木学会第70回年次学術講演会  (岡山) 

    Presentation date: 2015.09

  • 粒度幅の極端に広い材料により構成された河床の動的平衡状態

    鎌田遼

    土木学会第70回年次学術講演会  (岡山) 

    Presentation date: 2015.09

  • Gravel sorting and variation of riverbeds containing gravel, sand, silt and clay

    Masato SEKINE  [Invited]

    Gravel Bed Rivers 8  (Gifu) 

    Presentation date: 2015.09

  • NUMERICAL SIMULATION OF BARE-SLOPE EROSION CAUSED BY RAINFALL AND CHANNEL NETWORK FORMATION

    Masato SEKINE  [Invited]

    (Tokyo) 

    Presentation date: 2015.03

  • 粘土河床の浸食に及ぼす砂礫の移動量の影響

    野本高視

    土木学会第69回年次学術講演会  (大阪) 

    Presentation date: 2014.09

  • 骨格が大礫により構成された河床の動的平衡状態

    平松裕基

    土木学会第69回年次学術講演会  (大阪) 

    Presentation date: 2014.09

  • 三河島下水道処理区を対象とした東京都心部の内水氾濫危険性評価

    関根貴広

    土木学会第69回年次学術講演会  (大阪) 

    Presentation date: 2014.09

  • 芝浦下水道処理区を対象とした東京都心部の内水氾濫危険性評価

    竹順哉

    土木学会第69回年次学術講演会  (大阪) 

    Presentation date: 2014.09

  • 集中豪雨に伴う東京東部低平地の内水氾濫に関する数値解析

    池田遼

    土木学会第68回年次学術講演会  (千葉) 

    Presentation date: 2013.09

  • 集中豪雨による東京新宿の内水氾濫と地下空間の浸水危険性評価

    浅井晃一

    土木学会第68回年次学術講演会  (千葉) 

    Presentation date: 2013.09

  • 降雨による斜面浸食と流路群形成に及ぼす斜面勾配の影響

    石川学

    土木学会第68回年次学術講演会  (千葉) 

    Presentation date: 2013.09

  • 大礫を骨格とする河床の動的平衡状態に関する研究

    劒持尚樹

    土木学会第68回年次学術講演会  (千葉) 

    Presentation date: 2013.09

  • 砂礫の輸送による粘土河床の変動に関する実験的研究

    野本高視

    土木学会第68回年次学術講演会  (千葉) 

    Presentation date: 2013.09

  • 東京駅を含む都心部の広範な地域を対象とした内水氾濫の数値解析

    竹順哉

    土木学会第67回年次学術講演会  (愛知) 

    Presentation date: 2012.09

  • 三つの粒径集団の砂礫からなる河床の静的安定状態

    門井勇樹

    土木学会第67回年次学術講演会  (愛知) 

    Presentation date: 2012.09

  • 降雨による斜面浸食過程に及ぼす土砂の粒径の影響

    多田篤史

    土木学会第67回年次学術講演会  (愛知) 

    Presentation date: 2012.09

  • 掃流砂礫が粘着性河床の浸食に及ぼす影響

    野村正和

    土木学会第67回年次学術講演会  (愛知) 

    Presentation date: 2012.09

  • 骨格となる大礫の配置が河床の静的安定状態に与える影響

    平松裕基

    砂防学会第61回研究発表会  (高知) 

    Presentation date: 2012.05

  • 雨滴径の異なる降雨による斜面の浸食過程

    田中翔真

    土木学会第66回年次学術講演会  (愛媛) 

    Presentation date: 2011.09

  • 粘着性を有する流路の動的安定形状に関する研究

    岡幸宏

    土木学会第66回年次学術講演会  (愛媛) 

    Presentation date: 2011.09

  • 三つの粒径集団の砂礫により構成された河床の静的安定状態

    平松裕基

    土木学会第66回年次学術講演会  (愛媛) 

    Presentation date: 2011.09

  • 三つの粒径集団の土砂により構成された河床の静的安定状態に関する研究

    平松裕基

    砂防学会第60回研究発表会  (神奈川) 

    Presentation date: 2011.05

  • RECENT PROGRESS OF SEDIMENT TRANSPORT RESEARCH AND PREDICTION OF BED DEFORMATION

    Masato SEKINE  [Invited]

    Annual Journal of Hydraulic Engineering, JSCE, Vol.55 (Keynote Paper)  (Tokyo) 

    Presentation date: 2011.03

  • 河床骨格が大礫で構成された河床の流砂過程とその静的安定状態に関する実験的研究

    三國寛正

    土木学会第65回年次学術講演会  (北海道) 

    Presentation date: 2010.09

  • 粘着性土の浸食速度に及ぼす粘土含有率の影響

    白川剛

    土木学会第65回年次学術講演会  (北海道) 

    Presentation date: 2010.09

  • 複雑な構造を持つ地下空間における浸水時避難行動に関する数値解析

    大野龍馬

    土木学会第65回年次学術講演会  (北海道) 

    Presentation date: 2010.09

  • 河床骨格が大礫により構成された河道における流砂現象に関する研究

    三國寛正

    砂防学会第59回研究発表会  (長野) 

    Presentation date: 2010.05

  • 2008 年8 月に発生した雑司ヶ谷下水道幹線の水難事故に関わる数値解析

    青野雅士

    土木学会第64回年次学術講演会  (福岡) 

    Presentation date: 2009.09

  • 降雨による斜面浸食過程に及ぼす植物の葉および根の影響

    鍋島康大

    土木学会第64回年次学術講演会  (福岡) 

    Presentation date: 2009.09

  • 透水性の高い平地上に形成される模擬扇状地に関する再現計算

    小笠原基

    土木学会第64回年次学術講演会  (福岡) 

    Presentation date: 2009.09

  • 粘着性を有する流路の変動過程に関する実験的研究

    白川剛

    土木学会第64回年次学術講演会  (福岡) 

    Presentation date: 2009.09

  • 複断面蛇行流路内の流れ場に関する数値解析

    瀬野裕介

    土木学会第63回年次学術講演会  (宮城) 

    Presentation date: 2008.09

  • ダム排砂を想定した土砂供給による河床の粒度変動過程

    境崇充

    土木学会第63回年次学術講演会  (宮城) 

    Presentation date: 2008.09

  • 微細土砂の供給を受ける礫床河道の平衡河床に関する数値解析

    西俊彰

    土木学会第63回年次学術講演会  (宮城) 

    Presentation date: 2008.09

  • 実河川に堆積した粘着性土の浸食速度評価に関する実験的研究

    樋口敬芳

    土木学会第62回年次学術講演会  (広島) 

    Presentation date: 2007.09

  • 2005年に石神井川流域で発生した外水氾濫に関する数値解析

    中村康朋

    土木学会第62回年次学術講演会  (広島) 

    Presentation date: 2007.09

  • 大河川からの越水を想定した東京東部地域の外水氾濫に関する数値解析

    秋本健輔

    土木学会第62回年次学術講演会  (広島) 

    Presentation date: 2007.09

  • 環境ホルモン物質の河道内貯留に関わる一考察

    串田有気

    土木学会第62回年次学術講演会  (広島) 

    Presentation date: 2007.09

  • 降雨による斜面浸食過程に及ぼす植生の根系の影響に関する実験的研究

    大前謙友

    土木学会第62回年次学術講演会  (広島) 

    Presentation date: 2007.09

  • 礫・シルト充填河床モデルを用いた河道の非定常準二次元変動解析

    林将宏

    土木学会第62回年次学術講演会  (広島) 

    Presentation date: 2007.09

▼display all

Specific Research

  • 粒径の幅が極端に大きな土砂からなる河床上の流砂現象の解明に関する研究

    2015  

     View Summary

    本研究では,極端に広い粒度幅をもつ材料により構成される河床に注目し,上流側から供給されてくる砂礫の量ならびに質の違いに応じて,河床がいかなる動的平衡状態に達するかを明らかにした.河床材料は,一般に,移動しない大礫(L粒子),掃流砂として移動する砂礫(M粒子),浮遊砂として移動する砂あるいはシルト(S粒子)の三つの粒径集団に分けられることから,ここでは各々の集団をひとつずつの大きさの材料で代表させることにし,M-S粒子の供給量ならびにその体積比率などを系統的に変化させた一連の実験を行った.その結果として,動的平衡状態の河床が5段階に整理されることがわかり,その河床の鉛直構造が明らかになった.

  • 裸地斜面の侵食過程に及ぼす粘着性土の影響とこの過程に関する数値解析モデルの開発

    2004  

     View Summary

    流域における健全な土砂収支のあり方について今後考えていくためには,「河川上流域にある裸地斜面や崩壊地から生産・流出される土砂量」を定量的に評価していく手法と,その予測技術とが不可欠であると言えます.しかし,これについては必ずしも十分と言える情報があるわけではなく,十分な精度をもってこの土砂量を予測することもまた容易でないと言わざるをえません.そこで,著者らは,次のような二つの段階に分けて研究を進めてきました.まず,第一に,粘着性土を含まない砂礫からなる斜面の浸食過程を対象として,室内模型実験と数値解析を通じて検討を行いました.その結果,現象の理解はかなりのところまで深まり,あわせてその数値予測も十分に満足のいく精度で行うことが可能になったと判断しております.成果として特徴的な点を挙げれば,浸食により斜面上には樹枝状の流路が形成されること,斜面下端からの流出土砂量の時間変化は,この流路内で進行する土砂の浸食・堆積の素過程と密接に絡み合いながら生じること,などが明らかになりました.次に,実際の裸地斜面や崩壊地を構成する土砂には,その比率は異なるものの粘着性土が含有されていることに鑑み,前述の浸食の過程に及ぼす粘着性土の影響について検討してきました.このような検討は,実験技術的にも難しいことから,これまでほとんど手つかずの状態で残されてきました.本研究では,助成費を活用して室内実験装置を再構成し,新たな計測システムを導入することで,これまでになく制御された実験を行い,土砂の粘着性が斜面浸食過程に及ぼす影響の本質に迫ることできたと考えています.ただし,問題の複雑さから今後に残された課題も少なくなく,引き続き検証実験を継続することで更なる発展を図る必要がありますが,この研究によって今後の研究をいかに進めるべきかが明らかになり,この点でも価値ある研究の基礎固めができたと考えています.

  • 河岸に植生群落を伴うウォッシュロードの堆積とそれに伴う流路の安定化に関する研究

    1998  

     View Summary

     本研究では、まず植生を伴わない河道を対象として、シルトや粘土がウォッシュロードとして輸送された場合に、これらが低水路水際線に沿って堆積を引き起こすメカニズムを明らかにする水路実験を行っている。その結果、川幅の縮小にまで発達するウォッシュロードの堆積は、洪水前後のような流量変動が生じる場合の減水期により顕著な形で生じることが理解された。次に、低水路水際線に沿って樹木状の植生群落が生じている場合を対象として、群落の配置パターンの違いによる流れ場の変化について系統的な実験を行った。その中でも、植生群落が左右岸に交互に繁茂している場合には、群落を避けて流れるような特徴的な「蛇行流」が誘起されることを明らかにし、群落の規模や幾何学的形状、群落間の距離などの配置条件の違いによって「蛇行流」のパターンが大きく変化することを示している。さらに、この流れによって、群落一つに対して「洗掘域と砂州」とからなる一組の河床パターンが周期的に形成されることが理解された。このことは、低水路河岸に植生群落が帯を成して繁茂する場合に、ここで検討したような交互配置となるように植生群落を残すことで、人工的な手だてを講じることなく、多様な河川空間を創造することができることを示唆している。 また、このような実験的研究と平行して、一旦堆積したシルト・粘土が再び浸食されるメカニズムを明らかにするための、粘着性材料の浸食実験も進めてきている。ここでは、粘土と砂とからなる土塊を供試体とし、その粘土含有率を変化させた一連の実験を行い、土塊の浸食速度が粘土含有率に応じて特徴的な変化をパターンを示すことなど、今後に向けて有用な知見が得られている。このように、このテーマに関して今後研究を展開していく上での基礎を固めることができた。

  • 土砂粒子の運動の解析に基づく河床波の形成機構に関する研究

    1997  

     View Summary

    本研究では、均一粒径砂礫により構成される平坦河床が、土砂の移動に伴って河床波を伴う河床へと変化していく過程を、個々の土砂粒子の運動の解析を通じて再現し、その機構を明らかにしようとするものである。なお、ここでいう「土砂粒子の運動」とは、河床を構成している粒子が河床から抜け出し、流水中を運動した後、再び河床に停止するまでの一連の動きを指し、粒子の質点系の運動方程式を数値的に解くことでこの運動を追跡しようとするものである。この解析手法の骨格は著者らによって既に確立されている(たとえば、SEKINE and KIKKAWA、 1992)が、これを河床波などの地形が形成される過程の解析に適用しようとした研究はほとんど見られない。ところが、最近のコンピューターの処理能力の向上と、本研究を含む一連の研究により、ようやく地形形成のシミュレーションが可能な段階にきたといえる。 本研究で得られた主な成果は次の通りである。すなわち、(1) 土砂の移動し易さと河床の凹凸への捕捉のされ難さが河床表層粒子の配列などの幾何学的条件によって異なることによって河床上の微地形は発達・成長を遂げ、小規模の河床波となることがわかった、(2) 一度形成された凹凸は時間とともにその規模を増大させるが、その際に、波は上流方向に遡上しながら複数のより規模の小さな波がひとつにまとめられていくことがわかった。なお、砂漣や砂堆として知られる規模の大きな河床波の発達過程においては、波は下流方向に移動することが知られており、両者の移動方向は正反対である。ここで解析を行った初期河床波が砂漣・砂堆にまで成長し得るのか、その過程のどの段階でなぜ移動方向が変わるのかについては未解明であり、今後の課題としたい。最後に、(3)粒子スケールの運動の追跡を基礎として地形形成過程を解析する一手法を確立することができた。研究成果の発表:1997年9月「土砂粒子の運動の解析に基づく河床波の形成過程に関する研究」、土木学会題2回年次学術講演会概要集、第2部。1999年投稿予定「土砂粒子の運動の解析に基づく河床波の形成機構に関する研究(仮題)」、土木学会論文集。

  • 扇状地の形成過程に関する土砂水理学的研究

    1996  

     View Summary

     本研究は、河川により運ばれた土砂が扇状地を形成する過程を土砂水理学的に理解することを目的として行われたものである。一般に扇状地は透水性の高い砂礫により構成されており、そこを流れる河川水の多くが浸透し、伏流水となるため、扇央部では水無し川になることさえある。そこで、このような扇状地の形成過程を理解する上で、表面流と浸透流との相互作用と、表面流の浸透に伴う輸送土砂の堆積過程についての知見を得ることは重要な意味をもつ。さらに、その土砂の堆積によって扇状の地形が形成される過程において、流路はひとつところに留るわけではなく、「首振り」と呼ばれる流路のシフトが頻繁に生じることになるが、その素過程については未だ十分な力学的な理解が得られているわけではない。本研究では、こうした点に注目し、河川地形の形成機構に関わる基礎的な実験を行った。ここでは、土砂の輸送形式として掃流砂のみによるものを対象とし、他の研究者らにより進められている土石流の堆積に伴う地形の形成については検討の範囲外としている。 本研究における実験では、堆積地形が形成される平地の地表面下に広がる透水層の透水性を変化させるほか、透水層内の水位を制御し、表面流から浸透流への遷移状況を変化させるなどして、土砂の堆積過程に生じる変化を系統的に調べた。その結果、(1) 透水性が高いほど土砂の堆積が促進され、堆積厚が大きく面積の小さな地形となることや、(2)透水性が低いほど円弧状のデルタの形成の際に見られるプロセスと類似のものとなること、さらには、(3) 扇状の堆積となるためには、流路の首振り・分岐が不可欠であり、これは砂面上の力学的不安定が原因となっていること、などの結論が得られた。さらに、扇状地が幅広い粒度分布をもった砂礫により構成されていることに着目し、堆積地形の地表面下に生じる「土砂の分級」についても詳細な解析を行い、興味深い成果を得ている。

 

Syllabus

▼display all

 

Social Activities

  • テレビ朝日 報道ステーション

    テレビ朝日 報道ステーション 

    2009.10
    -
     

     View Summary

    都市型水害特集

  • テレビ朝日 報道ステーション

    テレビ朝日 報道ステーション 

    2009.08
    -
     

     View Summary

    都市水害,雑司ヶ谷下水道事故

  • NHK おはよう日本

    NHK おはよう日本 

    2009.08
    -
     

     View Summary

    都市水害,雑司ヶ谷下水道事故

  • NHK 週間ニュース

    NHK 週間ニュース 

    2009.08
    -
     

     View Summary

    都市水害,地下浸水

  • テレビ朝日 報道ステーション

    テレビ朝日 報道ステーション 

    2006.10
    -
     

     View Summary

    都市水害

  • NHK教育 サイエンスZERO

    NHK教育 サイエンスZERO 

    2006.08
    -
     

     View Summary

    急増する都市水害

▼display all