研究者データベース

岩崎 理樹(イワサキ トシキ)
工学研究院 土木工学部門 自然災害適応
准教授

基本情報

所属

  • 工学研究院 土木工学部門 自然災害適応

職名

  • 准教授

学位

  • 博士(工学)(北海道大学)

J-Global ID

研究キーワード

  • 数値計算   地形変動   河川工学   水工学   

研究分野

  • 社会基盤(土木・建築・防災) / 水工学

職歴

  • 2019年06月 - 現在 北海道大学 工学研究院 准教授
  • 2016年06月 - 2019年05月 寒地土木研究所 寒地河川チーム 研究員
  • 2014年05月 - 2016年05月 イリノイ大学アーバナシャンペーン校 土木工学科 博士研究員
  • 2013年04月 - 2014年05月 北海道大学 工学研究科 博士研究員

学歴

  • 2010年04月 - 2013年03月   北海道大学   工学院   環境フィールド工学部門
  • 2008年04月 - 2010年03月   北海道大学   工学院   北方圏環境政策工学専攻
  • 2006年04月 - 2008年03月   北海道大学   工学部   土木工学科
  • 2001年04月 - 2006年03月   苫小牧工業高等専門学校   環境都市工学科

所属学協会

  • アメリカ地球物理連合   土木学会   

研究活動情報

論文

  • Toshiki Iwasaki, Gary Parker
    Proceedings of the National Academy of Sciences of the United States of America 2020年01月 [査読有り][招待有り]
  • Shimizu Yasuyuki, Nelson Jonathan, Ferrel Kattia Arnez, Asahi Kazutake, Giri Sanjay, Inoue Takuya, Iwasaki Toshiki, Jang Chang-Lae, Kang Taeun, Kimura Ichiro, Kyuka Tomoko, Mishra Jagriti, Nabi Mohamed, Patsinghasanee Supapap, Yamaguchi Satomi
    EARTH SURFACE PROCESSES AND LANDFORMS 2019年07月17日 [査読有り][通常論文]
  • Zhang Li, Iwasaki Toshiki, Li Tiejian, Fu Xudong, Wang Guangqian, Parker Gary
    SCIENTIFIC REPORTS 9 2019年04月16日 [査読有り][通常論文]
  • 岩崎 理樹, 岡部 博一, 島田 友典, 矢部 浩規, 米元 光明
    寒地土木技術研究 : 国立研究開発法人土木研究所寒地土木研究所月報 : monthly report 786 11 - 20 土木研究所寒地土木研究所 2018年11月 [査読無し][通常論文]
  • Toshiki Iwasaki, Satomi Yamaguchi, Hiroki Yabe
    E3S Web of Conferences 40 2018年09月05日 [査読無し][通常論文]
     
    © The Authors, published by EDP Sciences, 2018. An understanding of bedload transport processes is an essential research goal for better prediction of river morphology and morphodynamics as well as the transport and fate of sediment-bound materials in river systems. Passive tracer particles have been used widely to monitor bedload transport processes in rivers by measuring the spatiotemporal distribution of the bedload tracers. Here, we propose a numerical model for reproducing the transport of bedload tracers in river systems, more specifically, the behaviours of bedload tracers under the influence of complex river morphodynamics. A two-dimensional morphodynamic model is combined with a flux-based bedload tracer model with use of the active layer approach. The model is applied to a laboratory experiment that demonstrates the transport processes within the channel of bedload tracers supplied from the floodplain. The numerical model effectively reproduces the main features of the experiment, namely, the bedload tracers supplied from the floodplain due to bank erosion deposit onto sand bars developed within the channel. Because the sand bars cause a very long residence time of the bedload tracers within the bed, the transport speed of the tracers is slowed significantly under the influence of bar formation and channel migration.
  • Jun Okuda, Yasuyuki Shimizu, Tomoko Kyuka, Toshiki Iwasaki, Yoshiaki Ishida
    Proceedings - International Association for Hydro-Environment Engineering and Research (IAHR)-Asia Pacific Division (APD) Congress: Multi-Perspective Water for Sustainable Development, IAHR-APD 2018 2 1007 - 1014 2018年09月01日 [査読無し][通常論文]
     
    © Proceeding of the 21st LAHR-APD Congress 2018. All rights reserved. There was a record breaking rainfall by Typhoon Lionrock over eastern Hokkaido in August 2016. Two levee breaches were caused by this rainfall leading to inundation disaster at Ikutora region in Minami Furano town. According to a field survey, the inundation disaster started from an upstream point at first, then the flood flow went through a flood plain and reached a downstream levee, finally overtopping to a river channel caused the second breach at downstream point. Since the flood started during midnight, a detailed explanation of the flood's behavior and a procedure of breaches remain unclear. In this study, we have investigated the river channel deformation and the levee erosion using a 2-dimensional numerical analysis. The computed results showed good agreement with field survey data regarding the inundation area, breach points, and the river channel deformation. Especially, the starting time of the inundation in the numerical analysis agreed with expected time estimated by field survey reports. The computational results indicate that with the increase of discharge, the development of a point bar pushed the channel near the upstream of the breach point toward outer bend of the channel meander. This channel migration may cause severe levee erosion. In the same time, the water level went up and overtopping flow happened. It suggests that both the bank erosion caused by the channel migration and overtopping flow caused the large-scale levee breach. Regarding the downstream breach, the results showed that the breach was caused by an overtopping flow from the floodplain to the river channel. which was expected by the field survey.
  • 濱木 道大, 岩崎 理樹, 井上 卓也, 清水 康行
    水工学論文集 Annual journal of Hydraulic Engineering, JSCE 63 I_955 - 960 土木学会 2018年 [査読無し][通常論文]
  • 岩崎 理樹, 井上 卓也, 音田 慎一郎, 矢部 浩規
    水工学論文集 Annual journal of Hydraulic Engineering, JSCE 63 I_643 - 648 土木学会 2018年 [査読無し][通常論文]
  • 岩崎 理樹, 井上 卓也, 矢部 浩規
    土木学会論文集B1(水工学) 74 4 I_1207 - I_1212 公益社団法人 土木学会 2018年 [査読無し][通常論文]
     
    本研究は,急流河川に発生する三角波が河川構造物に及ぼす影響を把握する水理実験を実施するものである.移動床条件で三角波が発生する水理条件においても,平坦固定床条件では三角波が発生しないことを利用し,固定床と移動床条件で底面に設置されたブロックの移動特性の違いについて比較した.実験結果より,平坦固定床条件で移動しない条件であっても,三角波が発生することでブロックが移動する可能性があることがわかった.三角波発生条件で生じる水面波と河床波による瞬間的な高流速や,反砂堆上に生じる上昇流がブロックの不安定化に寄与していることが示唆された.この結果は,三角波の発生を想定せずに,平坦固定床条件でブロックの設計重量を計算すると,危険側の設計となることを示唆している.
  • 山口 里実, 久加 朋子, 清水 康行, 泉 典洋, 渡邊 康玄, 岩崎 理樹
    土木学会論文集B1(水工学) 74 4 I_1153 - I_1158 公益社団法人 土木学会 2018年 [査読無し][通常論文]
     
    急流河川において出水時の流路変動による大規模な側岸侵食は深刻な災害を引き起こす.本研究では,出水時の土砂動態と大規模侵食を誘発する流路変動の関係を把握することを目的とし,特に河道内の土砂動態と流路変動との関連性を検討した.ペケレベツ川と音更川の出水時の河道内土砂収支を整理し,側岸からの流出土砂が供給源となり河道内へ堆積することで側岸侵食が拡大した可能性を示した.また,側岸からの流出土砂量の違いが流路変動へ与える影響を実験的に検討し,側岸から流出する土砂が直下流の砂州の外岸側への拡大に寄与することで大規模侵食を誘発する流路変動の要因となり得ることを示した.
  • 濱木 道大, 岩崎 理樹, 井上 卓也, 佐藤 大介, サムナー 圭希, 清水 康行
    土木学会論文集B1(水工学) 74 4 I_1033 - I_1038 公益社団法人 土木学会 2018年 [査読無し][通常論文]
     
    近年,全国的に河床低下傾向となっている河川が増加しており,総合土砂管理の考え方に基づき土砂還元等による対策が試行されている.しかし,還元した土砂を追跡する有効な手法が確立されておらず,効果検証に課題が残っている.本論文では,土砂還元による流砂追跡手法を開発することを目的として,室内水路実験による着色流砂(トレーサー)の追跡実験を行い,トレーサー群の平均的な移動速度及び分散状況を把握した.更に,トレーサー濃度を考慮した平面2次元河床変動解析による再現検証を行い,平均的な流砂の移動速度(表層濃度の到達距離)を精度良く再現するためには,鉛直方向の分散現象を考慮した交換層厚の設定が有効であることを見出した.
  • Yan Qina, Iwasaki Toshiki, Stumpf Andrew, Belmont Patrick, Parker Gary, Kumar Praveen
    EARTH SURFACE PROCESSES AND LANDFORMS 43 1 218 - 228 2018年01月 [査読有り][通常論文]
  • 岩崎 理樹, 川村 里実, 矢部 浩規
    寒地土木技術研究 : 国立研究開発法人土木研究所寒地土木研究所月報 : monthly report 774 2 - 10 土木研究所寒地土木研究所 2017年11月 [査読無し][通常論文]
  • Toshiki Iwasaki, Jonathan Nelson, Yasuyuki Shimizu, Gary Parker
    JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE 122 4 847 - 874 2017年04月 [査読有り][通常論文]
     
    Asymptotic characteristics of the transport of bed load tracer particles in rivers have been described by advection-dispersion equations. Here we perform numerical simulations designed to study the role of free bars, and more specifically single-row alternate bars, on streamwise tracer particle dispersion. In treating the conservation of tracer particle mass, we use two alternative formulations for the Exner equation of sediment mass conservation: the flux-based formulation, in which bed elevation varies with the divergence of the bed load transport rate, and the entrainment-based formulation, in which bed elevation changes with the net deposition rate. Under the condition of no net bed aggradation/degradation, a 1-D flux-based deterministic model that does not describe free bars yields no streamwise dispersion. The entrainment-based 1-D formulation, on the other hand, models stochasticity via the probability density function (PDF) of particle step length, and as a result does show tracer dispersion. When the formulation is generalized to 2-D to include free alternate bars, however, both models yield almost identical asymptotic advection-dispersion characteristics, in which streamwise dispersion is dominated by randomness inherent in free bar morphodynamics. This randomness can result in a heavy-tailed PDF of waiting time. In addition, migrating bars may constrain the travel distance through temporary burial, causing a thin-tailed PDF of travel distance. The superdiffusive character of streamwise particle dispersion predicted by the model is attributable to the interaction of these two effects.
  • 島田 友典, 渡邊 康玄, 岡部 博一, 岩崎 理樹, 中島 康博
    水工学論文集 Annual journal of Hydraulic Engineering, JSCE 61 Ⅰ_1345 - 1350 土木学会 2017年 [査読無し][通常論文]
  • 内山 雄介, 東 晃平, 小谷 瑳千花, 岩崎 理樹, 津旨 大輔, 上平 雄基, 清水 康行, 恩田 裕一
    土木学会論文集B2(海岸工学) 73 2 I_685 - I_690 公益社団法人 土木学会 2017年 [査読無し][通常論文]
     
    福島新田川流域には原発事故直後に大量の放射性セシウム137が大気経由で沈着し,河道に集積した高濃度の懸濁態<sup>137</sup>Csが出水毎に間欠的に海域へ供給され,沿岸域の底質環境に影響を与え続けている.本研究では,4段ネストJCOPE2-ROMS海洋モデル,多粒径3次元土砂輸送モデル,波浪推算モデルSWAN,河道モデルiRIC-Nays2DH,放射性核種吸着モデルを連成させた超高解像度広域土砂・懸濁態<sup>137</sup>Cs海洋分散モデリングを行い,台風201326号出水イベントに伴う河川起源土砂の河口・沿岸域における堆積・浸食状況の時空間特性を評価した.さらに懸濁態<sup>137</sup>Csインベントリ解析を行い,水深5 mまでの河口域,水深10mまでの河口外縁域での堆積,沿岸漂砂等による河川起源<sup>137</sup>Csの海域堆積層への移行特性を定量化した.
  • 島田 友典, 渡邊 康玄, 岡部 博一, 岩崎 理樹, 中島 康博
    土木学会論文集B1(水工学) 73 4 I_1345 - I_1350 公益社団法人 土木学会 2017年 [査読無し][通常論文]
     
    近年,堤防決壊が頻発する中,破堤被害軽減技術の構築は重要であるが,それには破堤現象の解明が不可欠である.千代田実験水路を用いた破堤実験により様々な知見を得ているが限られた河道条件である.そこで実験をもとに開発された数値計算モデルを用いて,川幅と河床勾配が破堤現象に与える影響について検討を行った.河床が急勾配では川幅の広狭によらず縦断方向に破堤拡幅が進行すること,河床勾配が緩くなるにつれ落掘の発達が顕著になり川幅が広くなると氾濫流況は正面越流に近くなることなど,河道特性を4つのカテゴリーに分類し破堤現象の相違を明らかにし,効果的な減災工法の考え方を示した.
  • 岩崎 理樹, 井上 卓也, 矢部 浩規
    土木学会論文集B1(水工学) 73 4 I_901 - I_906 公益社団法人 土木学会 2017年 [査読無し][通常論文]
     
    本論文は,非静水圧の影響を考慮した水深積分モデルである原形ブシネスクモデルと非平衡流砂モデルを組み合わせた二次元モデルが持つ三次元河床擾乱に対する不安定性について線形安定解析により明らかにし,これと三角状水面波列発生の関連性について議論を行うものである.線形安定解析の結果より,本モデルは反砂堆の三次元化をある程度表現できることがわかった.また,三次元反砂堆の縦横断方向卓越波数は,三角状水面波列の特性をよく表現しているが,波長を過大評価する傾向にあることが示唆された.
  • T. Inoue, T. Iwasaki, G. Parker, Y. Shimizu, N. Izumi, C. P. Stark, J. Funaki
    JOURNAL OF HYDRAULIC ENGINEERING 142 7 2016年07月 [査読無し][通常論文]
     
    Natural bedrock rivers exhibit diverse erosional morphologies. Although the formation of alternate bars on bedrock has been noted in previous studies, the influence of these alternate bars on bedrock erosion has not been clarified. In this study, the authors propose a model for bedrock-alluvial channels that reproduces both bar formation and erosional morphology. In addition, the authors report on numerical simulations to evaluate the influence of sediment supply on the state of the bed at and over the bedrock surface. The numerical results illustrate the formation of different morphologies for different supply rates. When the sediment supply rate is close to transport capacity, mixed alluvial-bedrock alternate bars form. These bars are analogous to purely alluvial alternate bars. A meandering thread of alluvial material migrates downstream over a uniformly eroding bedrock surface. When the sediment supply rate is well below capacity, however, multiple incisional troughs (grooves) form on the bedrock surface, and alluvial cover tends to concentrate in the troughs.
  • Toshiki Iwasaki, Yasuyuki Shimizu, Ichiro Kimura
    ADVANCES IN WATER RESOURCES 93 118 - 134 2016年07月 [査読有り][通常論文]
     
    Recent studies suggest that braided river could be single-thread channel by colonization of riparian vegetation; however, this kind of mutual interactions between physical and ecological processes in rivers are still poorly understood. Here we investigate the development of meandering channel in a river, which was originally braided and currently vegetated, the Otofuke River in Japan. The significant morphological processes of this river during a destructive flood event was studied using a two-dimensional morphodynamic model. Using well-calibrated parameters, this model qualitatively reproduced observed morphological changes such as the co-development of sand bars, bar-induced meandering and a chute cutoff. We find that for vegetated channels, meandering could maintain moderate sinuosity; in contrast, in the absence of riparian vegetation, bar-induced meandering channels could become braided. This suggests that distinct meandering channels could be a fundamental channel morphology in the originally braided, but currently vegetated river; however, the simultaneous occurrence of the chute cutoff and meandering indicates that this channel could not be a fully-developed high amplitude meandering channel. (C) 2015 Elsevier Ltd. All rights reserved.
  • Jonathan M. Nelson, Yasuyuki Shimizu, Takaaki Abe, Kazutake Asahi, Mineyuki Gamou, Takuya Inoue, Toshiki Iwasaki, Takaharu Kakinuma, Satomi Kawamura, Ichiro Kimura, Tomoko Kyuka, Richard R. McDonald, Mohamed Nabi, Makoto Nakatsugawa, Francisco R. Simoes, Hiroshi Takebayashi, Yasunori Watanabe
    ADVANCES IN WATER RESOURCES 93 62 - 74 2016年07月 [査読有り][通常論文]
     
    This paper describes a new, public-domain interface for modeling flow, sediment transport and morphodynamics in rivers and other geophysical flows. The interface is named after the International River Interface Cooperative (iRIC), the group that constructed the interface and many of the current solvers included in iRIC. The interface is entirely free to any user and currently houses thirteen models ranging from simple one-dimensional models through three-dimensional large-eddy simulation models. Solvers are only loosely coupled to the interface so it is straightforward to modify existing solvers or to introduce other solvers into the system. Six of the most widely-used solvers are described in detail including example calculations to serve as an aid for users choosing what approach might be most appropriate for their own applications. The example calculations range from practical computations of bed evolution in natural rivers to highly detailed predictions of the development of small-scale bedforms on an initially flat bed. The remaining solvers are also briefly described. Although the focus of most solvers is coupled flow and morphodynamics, several of the solvers are also specifically aimed at providing flood inundation predictions over large spatial domains. Potential users can download the application, solvers, manuals, and educational materials including detailed tutorials at www.-i-ric.org. The iRIC development group encourages scientists and engineers to use the tool and to consider adding their own methods to the iRIC suite of tools. Published by Elsevier Ltd.
  • Toshiki Iwasaki, Yasuyuki Shimizu, Ichiro Kimura
    ADVANCES IN WATER RESOURCES 92 57 - 72 2016年06月 [査読有り][通常論文]
     
    A number of numerical models have been proposed to understand and simulate fluvial river morphodynamics; however, it is somewhat unclear whether all the models are able to consistently simulate flow-bed instability phenomena. This study investigates the sensitivity of free bar morphology in rivers to secondary flow models used in depth-averaged models using linear stability analyses and numerical simulations. Both the linear analyses and numerical simulations suggest that under certain hydraulic conditions, an equilibrium-type secondary flow model, which has been widely used in river morphodynamic models, fails to generate a finite wavelength and bar mode, allowing the inception of bars of infinitely short scale and infinitely high mode. Using a nonequilibrium-type secondary flow model avoids the un-physical formation of these incipient free bars, and gives better solutions regarding finite amplitude bars. Since free bars are essential, intrinsic river morphological features, the findings of this study can be applied to a wide range of river morphodynamic calculations. (C) 2016 Elsevier Ltd. All rights reserved.
  • 山西 琢文, 内山 雄介, 岩崎 理樹, 清水 康行, 津旨 大輔, 三角 和弘, 恩田 裕一
    土木学会論文集B2(海岸工学) 72 2 I_757 - I_762 公益社団法人 土木学会 2016年 [査読無し][通常論文]
     
    二級河川福島県新田川の流域には福島原発事故直後に大量の<sup>137</sup>Csが大気経由で沈着し,河道内には高濃度の<sup>137</sup>Csが吸着した土砂が堆積していた.本研究では,荒天・出水イベントによる事故直後の新田川河口および沿岸域における陸域起源の<sup>137</sup>Csインベントリを定量的に評価するために,iRIC-Nays2DHをベースとした平面2次元河道モデルを用いた高出水時の河川流量および粒径別土砂流入フラックスの計算結果を用いて,同河口域における新田川由来の懸濁態<sup>137</sup>Csの海洋分散解析を行った.河口域観測結果等も併せて検討した結果,2011年5月末の大出水時に新田川から流入した懸濁態<sup>137</sup>Csは,約一ヶ月経過しても70%程度が河口付近に残存していること,流入した懸濁態<sup>137</sup>Csは再懸濁と再輸送を繰り返しながら数ヶ月以上の長い時間スケールで再分配され,長期的には河口域から散逸することが示唆された.
  • 井上 卓也, 岩崎 理樹, 音田 慎一郎
    土木学会論文集A2(応用力学) 72 2 I_565 - I_574 公益社団法人 土木学会 2016年 [査読無し][通常論文]
     
    流れの抵抗に影響を及ぼす小規模河床波の発生・発達は,河川工学分野における重要テーマの一つである.本研究では,ブシネスク方程式と非平衡流砂モデルを組み合わせたモデルに対して線形安定解析を行った.また浅水流方程式や平衡流砂モデルを用いた場合の分析も行い,ブシネスク項や流砂の非平衡性が河床波の不安定性と波長へ与える影響を考察した.この結果,ブシネスク方程式のみ,もしくは非平衡流砂モデルのみでは,反砂堆の不安定性を表現できないが,2つを組み合わせることにより,既往の反砂堆実験結果と良好な整合性が得らることが確認された.
  • F. Schuurman, Y. Shimizu, T. Iwasaki, M. G. Kleinhans
    GEOMORPHOLOGY 253 94 - 109 2016年01月 [査読無し][通常論文]
     
    River meandering results from spatially alternating bank erosion and bar growth. Recent flume experiments and theory suggest that a continuous inflow perturbation is a requirement for sustained meandering. Furthermore, flume experiments suggest that bar-floodplain conversion is an additional requirement. Here, we tested the effects of continuous inflow perturbation and bar-floodplain conversion on meander migration using three numerical morphodynainic models: a 1D-model, and two 2D-models with one of them using adaptive moving grid. We focused on the interaction between bars and bends that leads to meander initiation, and the effect of different methods to model bank erosion and floodplain accretion processes on meander migration. The results showed that inflow perturbations have large effects on meander dynamics of high-sinuosity channels, with strong excitation when the inflow is periodically perturbed. In contrast, inflow perturbations have rather small effect in low-sinuosity channels. Steady alternate bars alone are insufficient to cause high-sinuosity meandering. For high-sinuosity meandering, bar-floodplain conversion is required that prevents chute-cutoffs and enhances flow asymmetry, whilst meandering with chute-cutoffs requires merely weak floodplain formation, and braiding occurs without floodplain formation. Thus, this study demonstrated that both dynamic upstream inflow perturbation and bar-floodplain conversion are required for sustained high-sinuosity meandering. (C) 2015 Elsevier B.V. All rights reserved.
  • 赤堀 良介, 赤松 良久, 岩崎 理樹, 乾 隆帝, 永野 博之, 上鶴 翔悟
    土木学会論文集B1(水工学) 71 4 I_1471 - I_1476 公益社団法人 土木学会 2015年 [査読無し][通常論文]
     
    Semimountainous areas in Yamaguchi and Shimane Prefectures suffered severe damage brought by floods on July 2013. The damages in these areas were characterized by the vulnerability of their backlands that consists of agricultural lands. In order to investigate the mechanisms of land erosion on these areas where existing high-resolution data was not prepared, post-disaster RTK-GPS surveys and numerical simulations were conducted for Abu River in Yamaguchi. The surveys were aimed at providing the high-resolution topographic datasets of these regions in order to evaluate the influences of micro-topography on channel incisions by the flood flow. The results of the numerical calculations of movable bed-evolution well reproduced the process of the channel incisions on these areas, and it implies that the micro-topography is one of the most influential factors on erosion and channel formation processes on such semimountanious regions.
  • 岩崎 理樹, PARKER Gary, 清水 康行
    土木学会論文集B1(水工学) 71 4 I_877 - I_882 公益社団法人 土木学会 2015年 [査読無し][通常論文]
     
    This paper presents numerical simulations of tracer particle transport both in the absence and presence of free bars. The transport and diffusion of tracer particles is affected by both the probabilistic motion of sediment particles and by the river bed geometry associated with free bars. We compare results of numerical models using an equilibrium (flux-based model) and a non-equilibrium (entrainment-based model) conservation formulation for river bed variation associated with bedload transport. The results show that 1) the entrainment-based morphodynamic model successfully reproduces free bar formation, 2) the flux-based morphodynamic model fails to simulate tracer diffusion in the absence of bars, and 3) free bar formation enhances streamwise tracer diffusion.
  • T. Iwasaki, M. Nabi, Y. Shimizu, I. Kimura
    Journal of Environmental Radioactivity 139 416 - 426 2015年01月01日 [査読無し][通常論文]
     
    © 2014 Elsevier Ltd. A numerical model capable of simulating the transfer of137Cs in rivers associated with transport of fine sediment is presented. The accident at Fukushima Dai-ichi Nuclear Power Plant (FDNPP) released radionuclides into the atmosphere, and after fallout several radionuclides in them, such as radiocesium (134Cs,137Cs) and radioiodine (131I) were adsorbed on surface soil particles around FDNPP and transported by surface water. To understand the transport and deposition of the radioactive contaminant along with surface soil particles and its flux to the ocean, we modeled the transport of the137Cs contaminant by computing the water flow and the associated washload and suspended load transport. We have developed a two-dimensional model to simulate the plane flow structure, sediment transport and associated137Cs contaminant transport in rivers by combining a shallow water flow model and an advection-diffusion equation for the transport of sediment. The proposed model has been applied to the lower reach of Abukuma River, which is the main river in the highly contaminated area around FDNPP. The numerical results indicate that most137Cs supplied from the upstream river reach with washload would directly reach to Pacific Ocean. In contrast, washload-oriented137Cs supplied from the upstream river basin has a limited role in the radioactive contamination in the river. The results also suggest that the proposed framework of computational model can be a potential tool for understanding the sediment-oriented137Cs behavior in rivers.
  • 岩崎 理樹, 清水 康行, 木村 一郎
    土木学会論文集B1(水工学) 70 4 I_1267 - I_1272 公益社団法人 土木学会 2014年 [査読無し][通常論文]
     
    A numerical model for calculating the behavior of radioactive contaminant associated with the sediment transport in rivers has been proposed in this study. The equations for simulating the concentration of radioactive contaminant of the sediment has been derived from the governing equation of the sediment transport model. The proposed model has been applied to a simple river confluence to understand the mixing process of the sediment and the radioactive contaminant in the confluence point. The numerical results provide a useful data for discussing the relation between the bed evolution process and the behavior of radioactive contaminant. In addition, the model can contribute to estimate the origin of the sediment by using the relationship between the simulated sediment diameter and the concentration of the radioactive contaminant.
  • M. Nabi, S. Giri, T. Iwasaki, I. Kimura, Y. Shimizu
    RIVER FLOW 2014 1253 - 1259 2014年 [査読無し][通常論文]
     
    We developed a morphodynamic model for generation and migration of dunes under shallow flow approximation. The flow was calculated by two-dimensional depth-averaged equations and the bed shear stress was found by fitting a log-low function at each grid cell. The shear stress then was adjusted by adding slope effect. As the bed features have smaller spatial scales than the flow, a two-grid approach is adopted. The flow is solved on a coarse grid and then the flow field is interpolated on a finer grid, on which the bed morphology is calculated. This technique enabled us to solve the morphological process for large scale applications. A parameterized relation is applied for bedload sediment transport and the bed evolution is updated using Exner equation. Two cases with different flow conditions are simulated and compared with experimental results and field measurements. The computed results show good agreement with experiments and field measurements.
  • R. Suzuki, I. Kimura, Y. Shimizu, T. Iwasaki, T. Hosoda
    RIVER FLOW 2014 179 - 187 2014年 [査読無し][通常論文]
     
    The secondary current of the second kind, which is initiated by the turbulence anisotropy, is a classical topic in fluid engineering and has been studied by many researchers with wide variety of methods. However, we have still controversy on this phenomenon, in particular, the secondary currents in open channels with larger aspect ratio (=B/h > 5, B: channel width, h: water depth). This paper investigated the fundamental characteristics of the secondary current of the second kind in wide shallow open channel flows through the comparison between 3-D (three-dimensional) URANS (Unsteady Reynolds Averaged Navier Stokes Equations) computations and results of laboratory experiments performed by Blanckaert et al. (2010). A second order non-linear k-epsilon model proposed by Ali et al. (2007) was employed as a turbulence model. First, we tried to carry out the computations under the same conditions of the laboratory tests by Blanckaert et al. We employed three cases in rectangular open channels with different depths for validating the numerical model. The computational results are generally in good agreement with the experimental results not only the cross-sectional secondary flow patterns but also patterns of Reynolds stresses and turbulence kinetic energy. The experimental results showed that the periodic vortices with streamwise axes are generated regularly in the cross section except the vicinity of side walls, and their diameter is almost same as the water depth. It means that the larger vortices are generated in case of larger depth. The same tendency was well simulated by the present computations. It has been pointed out in previous papers that the secondary currents of straight open channels are initiated by the surface vortex and the bottom vortex near the side walls, and the secondary current becomes weaker as the distance from the side wall increases. It has been reported that the clear secondary current is not generated at the region where the distance from the side wall is larger than 2.5 h (e.g., Nezu et al., 1985). However, such damping of vortex strength was not observed in the present computations as well as the experiments by Blanckaert et al. In order to check the effect of side walls to the secondary current, we performed the computation under the aspect ratio = 100. In this case, the secondary currents are again generated clearly in the whole channel and no damping effect is observed in the middle part. The result was also same even if a periodic boundary condition is adopted in the lateral direction to neglect completely the effect of side walls. Those results imply an important finding that the surface and bottom vortices near the side walls, which have been considered to drive the secondary current cells, are not a necessary source for generating secondary currents in entire cross section of a shallow straight open channel.
  • Toshiki Iwasaki, Yasuyuki Shimizu, Ichiro Kimura
    PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-MARITIME ENGINEERING 166 2 76 - 88 2013年06月 [査読有り][通常論文]
     
    The physical and numerical modelling of the initiation and development process of tidal creek network in tidal environments is presented herein. An attempt was made to reproduce the developing process of tidal creeks on a small experimental flume by considering the scaling rules of flow and sediment transport associated with tidal flows between the real scale and an experimental flume. In the experiments, the initial stage of channel evolution and the complex channel network configuration were successfully modelled, and results show that the similar network geometry observed in tidal environments can be reproduced at an experimental scale. Numerical simulations of initiation and development of tidal creeks were also undertaken using a two-dimensional-based morphodynamic model. The results indicated that the proposed numerical model simulated the geometry of channel network and its development process observed in the experiment reasonably well. In addition, a sensitivity analysis of grid resolution was carried out to show how grid resolution affected the computational results. The results implied that a grid size which can resolve the finer-scale channels that form in the initial stages of network development is required to simulate the evolution of tidal creeks adequately.
  • 木村 一郎, 山蔦 涼, 岩崎 理樹
    水工学論文集 土木学会水工学委員会 編 57 1_643 - 648 土木学会 2013年 [査読無し][通常論文]
  • 岩崎 理樹, 奥寺 亮太, 清水 康行, 木村 一郎
    土木学会論文集B1(水工学) 69 4 I_1093 - I_1098 公益社団法人 土木学会 2013年 [査読無し][通常論文]
     
    This paper presents a consideration of formation mechanism of tidal channel networks. We employed a simple mathematical model to explain the flow and bed evolution in intertidal zones. By assuming the regular periodic tidal wave and the simple bed geometry which has constant slope, we derived an advection - diffusion equation for the bed evolution. This equation has a Peclet type non dimensional number which expresses the ratio between advection and diffusion. We investigated this Peclet number in the experimental results conducted under the different hydraulic conditions. The results show that in the conditions with small Peclet number, which means that the diffusion effect is relatively strong, clear channel network can not develop on the bed surface. On the other hand, in large Peclet number conditions, clear and complicated channel network tends to develop.
  • 木村 一郎, 山蔦 涼, 岩崎 理樹, 清水 康行
    土木学会論文集B1(水工学) 69 4 I_643 - I_648 公益社団法人 土木学会 2013年 [査読無し][通常論文]
     
    A multi-level grid type turbulent shallow flow model combined with an equilibrium sediment transport model (KMR-MB: Kinematic Mesh Reconstruction for Movable Bed) is proposed. KMR method is a kind of multi-level grid model with dynamic refinement and combining grid cells to capture efficiently unsteady flow phenomena. Saito et al. (2012)1) have applied the KMR approach to open channel flows around a bridge pier and shown the advantage of the model. They used the maximum value of the strain and rotation parameters for the threshold for quad-tree and 3 x 3 type grid divisions. We have extended the model for computations of morphological phenomena in rivers by incorporating an equilibrium sediment transport model as well as a bed continuity equation, and employing new criteria for grid cell refinement. We employed an average curvature of the bed surface as the criteria for refinement and combining quad-tree type grid cells. The present model has been applied to simulate the alternative bar formations. The experimental result by Akahori et al (2011)2) was used for validation of the model. The comparison between numerical and experimental results showed that the present KMR-MB can simulate excellently the phenomena with less CPU time than the fixed grid computations.
  • 岩崎 理樹, 清水 康行, 木村 一郎
    土木学会論文集B1(水工学) 69 3 123 - 134 公益社団法人 土木学会 2013年 [査読無し][通常論文]
     
    本研究では,浅水流方程式と平衡掃流砂量式を基本とした河床変動モデルの特性と安定性について,微小な河床擾乱の伝搬計算を通じて検討を行った.方程式系を線形化することで,河床擾乱の伝搬を示す双曲型微分方程式を導出し,河床擾乱の伝搬特性について明らかにした.この時,平衡流砂量式の枠組みでモデル化される流砂量に対する局所勾配の影響は河床擾乱を拡散させる作用を持つ.双曲型方程式を安定的に計算する条件であるP&eacute;clet数が2以下となる条件を満たすように格子幅を設定すれば,流砂量の空間微分に対して風上化を導入せずとも,方程式が持つ不安定性を合理的に散逸させつつ,安定的な河床変動計算を実行できることを示した.
  • 岩崎 理樹, 清水 康行, 木村 一郎
    土木学会論文集B1(水工学) 69 3 147 - 163 公益社団法人 土木学会 2013年 [査読無し][通常論文]
     
    本研究は,平面二次元河床変動モデルにおける二次流のモデル化の違いが自由砂州の計算に与える影響について,線形安定解析,数値計算及び実験の結果を比較することで検討を行ったものである.一般に広く適用される局所的な流線湾曲に対して一様湾曲流における二次流解を適用すると,流砂移動に対する横断方向勾配の影響が相対的に小さい場合に高次モードの砂州ほど初期発達増幅率が大きくなる可能性を示した.また,二次流の発達・減衰を考慮したモデルを用いることで,物理的にこのような不安定成分を抑制でき,河床変動に対する二次流の影響を合理的に考慮可能であることが明らかとなった.構築した数値計算モデルは,理論卓越波長,砂州モードを良好に再現するとともに,平衡砂州波高の再現性も向上することが示された.
  • 田中 甫幸, 清水 康行, NELSON Jonathan, 岩崎 理樹
    土木学会論文集B1(水工学) 68 4 I_1033 - I_1038 公益社団法人 土木学会 2012年 [査読無し][通常論文]
     
    The Great Mississippi Flood of 1927 was the most destructive river flood in the history of the United States. After the flood in 1927, Mississippi River and Tributaries Project has carried out and changed the engineering policy. One of the biggest projects in MR&T project is the constriction of Birds Point-New Madrid Floodway. In 2011, May, Mississippi River had flooded dramatically and floodway had used which have not been used since 1937. By using floodway smoothly, explosion of levee had executed which was including in Birds Point-New Madrid Floodway operation measure. On our research, we evaluate the effect of the floodway and reproduce the flood by using numerical simulation. By our simulation, floodway has the effect to reduce the water level 1.5m~3m. We also simulate the characteristics of the floodway.
  • 岩崎 理樹, 清水 康行, 木村 一郎
    土木学会論文集B1(水工学) 68 4 I_979 - I_984 公益社団法人 土木学会 2012年 [査読無し][通常論文]
     
    This study presents the numerical simulations of initiation and development process of tidal creek network by using two-dimensional morphodynamic model including the seepage flow model, and also discusses the effect of seepage flow for development of tidal creek network. A two dimensional shallow flow equation and two dimensional saturated seepage flow model based on Darcy law were combined to simulate flow field both on and in the bed. The numerical tests with and without seepage flow model were carried out to understand the effect of seepage flow for development of tidal creek in simplified conditions. The result shows that, by including seepage flow model, the channel network tend to become complex one, which has a lot of small scale channels. In addition, the channel width and depth increases by the very shallow flows induced by water supply from inside the bed. This indicates that the seepage flow from inside the bed can have dominant effect for morphodynamics on tidal areas, especially in case of subjecting the dry and wet condition in the bed surface.
  • 禅野 浩貴, 岩崎 理樹, 清水 康行, 木村 一郎
    土木学会論文集B1(水工学) 68 4 I_865 - I_870 公益社団法人 土木学会 2012年 [査読無し][通常論文]
     
    It is important from the engineering point of view to predict the collapsing process of river embankment and behavior of overtop flow for reducing disaster during flood. We performed some considerations on refinement of a two-dimensional computational model based on shallow flow equations to predict more accurately the front overflow levee breach phenomena. We tried to introduce a levee erosion model instead of sediment transport model to evaluate the deformation of the levee. In addition, intermittent behavior of the bank collapse is modeled. A calibration of the numerical model is made through the comparison with field experimental data. Recently, a real-scale experiment on a front levee breach was carried out at the Chiyoda Experimental Channel in Hokkaido, Japan. We performed the computation under the same conditions in the experiment. The computational results showed that the present refined model can predict fundamental aspects of the front levee breach phenomena. breach phenomena.
  • Numerical simulation on bed evolution and channel migration in rivers
    Toshiki Iwasaki, Yasuyuki Shimizu, Ichiro Kimura
    RIVER FLOW 2012, VOLS 1 AND 2 673 - 679 2012年 [査読有り][通常論文]
     
    This paper presents the numerical simulation of sand bar evolution with bank erosion in the Otofuke river, Hokkaido, Japan. A great flood occurred in the Otofuke River, at Hokkaido region in September 6th, 2011 have caused the significant bed evolution and channel migration. As a result, a part of the river embankment was destroyed. To protect such damage of the river embankment during the flood, the complex interaction between flow, bed evolution and bank erosion in rivers have to be investigated. In this study, the flow and bed deformation of the Otofuke river during the flood was examined by using a depth-averaged two-dimensional morphodynamic model. The numerical result indicates that the alternate sand bars developed in low water channel at peak discharge and these sand bars creates the clear alternative thalweg. By the concentration of flows in the thalweg, the significant channel migration might occur during falling stage of discharge. This implies that unsteadiness of discharge is a one of key role to bank erosion process in case of co-existing of sand bars.
  • Geomorphological characteristics of female and male-type meanders
    Kozue Tanaka, Yasuyuki Shimizu, Satomi Yamaguchi, Toshiki Iwasaki, Ichiro Kimura, Gaku Tanaka
    7th IAHR Symposium on River, Coastal and Estuarine Morphodynamics(CD-ROM) 7 1824 - 1831 2011年 [査読有り][通常論文]
  • 岩崎 理樹, 渡部 靖憲, 奥寺 亮太, 清水 康行, 木村 一郎
    土木学会論文集B2(海岸工学) 67 2 I_951 - I_955 公益社団法人 土木学会 2011年 [査読無し][通常論文]
     
    The complex channel networks have dominant roles for flow, sediment and nutrient transport on salt marshes and tidal flats, and therefore provide rich habitat structures. This study discusses the fundamental geometric properties of tidal channel network by statistical analysis to their channel length and planimetric shapes. We employed channel networks which delineated from experimental and numerical result and also satellite image of real field. It is found that the probability density distribution of channel length can be described by a lognormal distribution, and network in experimental and real scale have similar properties for channel length. The results also indicate that the difference of tidal conditions change the characteristics of tidal channel network configuration.
  • 田中 甫幸, 清水 康行, 木村 一郎, 岩崎 理樹
    土木学会論文集B1(水工学) 67 4 I_895 - I_900 公益社団法人 土木学会 2011年 [査読無し][通常論文]
     
    The urbanization in Sapporo was started about only 140 years ago. Before the urbanization, the topography of most part of Sapporo was wetland and not suitable for living and cultivation. Intensive river training works have changed this area dramatically for relatively short period, and made Sapporo as one of the biggest cities in Japan with a population of 1.9 million. In this study, the history of river training works and the transition of inundation characteristics in Sapporo are investigated through old literatures and numerical simulations. First, the historical process of river training constructions was clarified by inspecting old documents and found out some key works. Then numerical simulations of flood were performed in three cases, namely, original topography, after construction of Toyohira-River- Bank and after construction of new Toyohira River Channel. The comparison of simulation results elucidated the relation between river training works and change of inundation behavior.
  • 岩崎 理樹, 清水 康行, 木村 一郎
    土木学会論文集B1(水工学) 67 4 I_859 - I_864 公益社団法人 土木学会 2011年 [査読無し][通常論文]
     
    This paper presents the laboratory tests on developing process of tidal creek network in the small flume and also validation of numerical model which can replicate the morphodynamic evolution of tidal channel and its geomorphic features. The experimental conditions fully satisfied the kinematic, dynamic and sediment transport similarities between the real and experimental scale. The channel network, which has the similar channel characteristics such as ratio between the channel width and depth observed in real field, was reproduced in the experimental flume. This study also conducted the numerical simulations with experimental conditions for validating the physically-based two-dimensional morphodynamic model. The results showed that the proposed morphodynamic model can simulate reasonably the geometry of channel network and its developing process observed in the experiment.
  • 禅野 浩貴, 岩崎 理樹, 清水 康行, 木村 一郎
    土木学会論文集B1(水工学) 67 4 I_853 - I_858 公益社団法人 土木学会 2011年 [査読無し][通常論文]
     
    Flood in rivers is a common disaster all over the world. If a levee breach happens, it sometimes causes a fatal disaster. In addition, many buildings, urban facilities, lifelines, etc. are seriously damaged. Detailed mechanism of a levee breach has not been clarified yet. Therefore, it is important to predict the collapsing process of riverbank and behavior of overtop flow for reducing damage. We applied a two-dimensional shallow flow computational model to levee breach phenomena caused by overflow and the performance of the model was elucidated. A calibration of the numerical model is made through the comparison with field experimental data. Recently, a real-scale experiment on a levee breach was carried out at the Chiyoda Experimental Channel in Hokkaido, Japan. We performed the computation under the same conditions in the experiment. The computational results showed the excellent performance for simulating levee breach phenomena.
  • 及川 森, 岩崎 理樹, 山口 里実, 清水 康行, 木村 一郎
    土木学会論文集B1(水工学) 67 4 I_751 - I_756 公益社団法人 土木学会 2011年 [査読無し][通常論文]
     
    The bed degradation is going rapidly in the upper part of the Ishikari River recently, owing to exposed bedrock erosion caused by bedload on the bedrock. In order to estimate the erosion rate of bedrock, we performed an experiment by a circular channel flume with artificial bedrock made of plaster. We applied the erosion rate estimated by the present experiment to a numerical simulation of bed deformation on the bedrock by using horizontal 2D flow model and the bedload layer model. The result of the simulation shows that gut pattern appeared in the simulated results which is very similar to the experimental result. It was found that the bed degradation was progressed by the erosion caused by sediment transport itself.
  • Toshiki Iwasaki, Yasuyuki Shimizu, Ichiro Kimura
    International Journal of River Basin Management 9 237 - 245 2011年01月01日 [査読無し][通常論文]
     
    This paper discusses the bed evolution and the grain sorting process in meandering channel by using a two-dimensional (2D) based morphodyamic model. In river bends, secondary currents, which are three-dimensional (3D) flow structures caused by a balance between centrifugal force and pressure gradient, has important roles for flow structure and the sediment transport. Therefore, a numerical model, which can reproduce this 3D flow structure, is required to describe the morphodynamic phenomena in meandering rivers. This study employed the depth-averaged 2D shallow water equations’ integrated effect of secondary currents of the first kind for flow calculations. This flow model can consider the effect of lag between the developments of secondary current and streamline curvatures. In addition, we employed the equilibrium sediment transport model and a multiple layer model for simulating the sediment transport and sorting phenomena due to non-uniform sediments. This study applied the different kind of model for evaluating the secondary current and sediment transport to a meandering channel with simple-rectangular sine-generated curve. We examined the applicability of models and morphodynamic process in a meandering channel through the comparison between the experimental and numerical results. The result shows that the correlation for secondary currents for flow structures and sediment transport is important to reproduce the bed evolution and sorting phenomena in river bends. © 2011 International Association for Hydro-Environment Engineering and Research.
  • 岩崎理樹, 清水康行, 木村一郎, 田中岳
    水工学論文集(CD-ROM) 53 ROMBUNNO.125  2009年02月 [査読有り][通常論文]
  • 舛屋 繁和, 清水 康行, 岩崎 理樹
    水工学論文集 52 607 - 612 公益社団法人 土木学会 2008年 [査読無し][通常論文]
     
    This study aims to develop a physically-based morphodynamic model in order to reproduce incision of tidal creek networks as well as evolution of geomorphology in the tidal environments. The process of incision and long-term geomorphologic evolution on tidal flats and marsh is of practical significance from the environmental view point. Generally, it is postulated that tidal creeks are developed as a result of ecomorphologic processes of tidal system driven by tidal energy. Some previous investigations have provided significant insight to this problem. However, there is still lack of a physically-based modeling approach that can replicate the initiation and evolution process of this phenomenon. In this study, physically-based model was applied to a narrow area referred to as tidal flats in order to provide quantitative and qualitative evaluation of its reproducibility. Calculation was conducted for different time scale up to 350 days. Calculation results revealed that the incision of tidal network and its initial development process can satisfactorily be reproduced by a physically-based computational model.
  • 岩崎 理樹, 清水 康行
    応用力学論文集 11 745 - 752 公益社団法人 土木学会 2008年 [査読無し][通常論文]
     
    In this paper, eco-morphological model is proposed to simulate morphology at tidal environment with vegetation growth. Two numerical experiments such as vegetated scenario and unvegetated scenario were performed to clarify influence of vegetation on morphological evolution. This model was applied to a square tidal flat and calculations were conducted for 350 days. Computational results show that a complicated channel network is formed on tidal marsh and natural levees were appeared around the channel network in both cases. In addition, the vegetation propagated along the natural levees. In vegetated scenario, sediment deposition was enhanced by effect of vegetation on natural levee in comparsion with unvegetated scenario. Therefore, these results indicated that tidal channels are formed more clearly due to vegetation.

その他活動・業績

受賞

  • 2019年11月 土木学会水工学委員会 水工学論文賞
     
    受賞者: 岩崎理樹
  • 2018年05月 北海道開発局 北海道開発技術研究発表会 寒地土木研究所長賞
     
    受賞者: 岩崎理樹
  • 2015年06月 土木学会 土木学会論文奨励賞
     
    受賞者: 岩崎理樹
  • 2013年03月 土木学会 水工学委員会 水工学論文奨励賞
     
    受賞者: 岩崎理樹
  • 2010年03月 土木学会 北海道支部 土木学会北海道支部年次講演会優秀学生講演賞
     
    受賞者: 岩崎理樹
  • 2008年03月 北海道大学 土木工学科 廣井賞
     
    受賞者: 岩崎理樹
  • 2006年03月 苫小牧工業高等専門学校 環境都市工学科 近藤賞
     
    受賞者: 岩崎理樹

共同研究・競争的資金等の研究課題

  • シームレス広域土砂輸送-地形変動モデルの構築と流域内の水土砂災害への脆弱性評価
    日本学術振興会:科学研究費助成事業 若手研究
    研究期間 : 2020年04月 -2023年03月 
    代表者 : 岩崎 理樹
  • 大量アンサンブル降雨―流出計算データを利用した流路変動解析による河道被災リスクの定量評価手法の構築
    国土交通省水管理・国土保全局:河川砂防技術研究開発 河川技術部門
    研究期間 : 2020年05月 -2021年03月 
    代表者 : 清水康行,泉典洋,今日出人,山田朋人,久加朋子,星野剛,山口里実,井上卓也
  • 混濁流による高流砂階のベッドフォームの堆積構造解明と堆積モデルの構築
    文部科学省:科学技術研究費補助金 基盤研究(B)
    研究期間 : 2018年04月 -2021年03月 
    代表者 : 横川美和
  • 令和元年台風19号及び台風21号による広域災害に関する総合研究
    日本学術振興会:科学研究費助成事業 特別研究促進費
    研究期間 : 2019年12月 -2020年03月 
    代表者 : 二瓶 泰雄, 中北 英一, 竹見 哲也, 山田 朋人, 三隅 良平, 飯塚 聡, 鈴木 真一, 仲江川 敏之, 柳瀬 亘, 立川 康人, 田中 茂信, 佐山 敬洋, 田中 智大, 朝位 孝二, 前野 詩朗, 田中 仁, 吉谷 純一, 田中 規夫, 泉 典洋, 矢野 真一郎, 森脇 亮, 赤松 良久, 内田 龍彦, 重枝 未玲, 岩崎 理樹, 清水 義彦, 小山 毅, 長谷川 兼一, 西嶋 一欽, 藤本 郷史, 毛利 栄征, 前田 健一, 岡村 未対, 卜部 厚志, 森口 周二, 蝦名 裕一, 松四 雄騎, 王 功輝, 竹林 洋史, 鈴木 素之, 田島 芳満, 佐々木 淳, 信岡 尚道, 森 信人, 有川 太郎, 鈴木 崇之, 下園 武範, 松井 正宏, 小林 文明, 畑山 満則, 牛山 素行, 佐藤 健, 梶谷 義雄
  • 土砂トレーサーを利用した土砂動態-地形変動過程の理解と予測
    文部科学省:科学技術研究費補助金 若手研究
    研究期間 : 2017年04月 -2020年03月 
    代表者 : 岩崎理樹
  • 日本学術振興会:科学研究費助成事業 基盤研究(B)
    研究期間 : 2015年04月 -2018年03月 
    代表者 : 横川 美和, 泉 典洋, 石原 与四郎, 成瀬 元, 岩崎 理樹, 大西 由梨, 大畑 耕治
     
    海底の混濁流の通り道にしばしば見られるサイクリックステップ(CS)の形成機構について,従来行われていなかった,短いサージ的な混濁流が何度も作用する実験を行った.主に長さ7mの水路を用いて,継続時間3秒,5秒,7秒の短い時間のサージ的混濁流(塩水+樹脂粒子)を130-140回ずつ流した.いずれも5-6個のCSが形成されたが,同じ単位時間流量で連続的に流すとCSは形成されず,サージ的混濁流によってCSができやすいこと等がわかった.実験結果を踏まえて,理論解析・数値シミュレーションを行った他,地層(宮崎層群)の混濁流堆積物中のセディメントウェーブ層準に適用して,詳細な調査から,堆積モデルを作成した.
  • 感潮域における持続可能な環境保全手法の確立に向けた地形変動予測モデルの開発
    文部科学省:科学技術研究費補助金 特別研究員奨励費
    研究期間 : 2010年04月 -2013年03月 
    代表者 : 岩崎理樹

大学運営

委員歴

  • 2018年03月 - 現在   土木学会 水工学委員会   基礎水理部会 部会員


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