論文 - 末次 大輔
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中詰め材と金網の種類の違いが蛇籠の圧縮特性に与える影響 査読あり
中澤博志，末次大輔，原忠，栗原裕之，西剛整
材料 73 ( 1 ) 46 - 51 2024年1月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Zairyo/Journal of the Society of Materials Science, Japan
The advantage of gabion structures is that they are simple, cost-effective, and quick to construct, and they are used in a wide variety of applications in Japan and abroad. However, despite the fact that wire mesh comprising the gabion has been used for a long time, there are few studies on its basic mechanical properties. Therefore, the design and construction of gabion structures are mostly based on experience due to the lack of established design methods. In this study, large triaxial compression tests on the stones for filling into gabion boxes and a series of compression tests on miniature gabions were carried out in order to understand the basic mechanical properties of the structures. From the tests, the compressive properties of the miniature gabions were found to be varied depending on the difference of geometry of the stone and the combination of the shape and direction of the wire mesh. These results suggest that an understanding on deformation mechanism of gabion structures is necessary for their reasonable design and construction.
DOI： 10.2472/jsms.73.46
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EFFECT OF DIATOMACEOUS EARTH ON DESICCATION CRACKING OF EXPANSIVE SOILS 査読あり
Tadesse A.B., Fukubayshi Y., Koyama A., Suetsugu D.
International Journal of GEOMATE 24 ( 105 ) 66 - 76 2023年5月
掲載種別：研究論文（学術雑誌） 出版者・発行元：International Journal of GEOMATE
Expansive soils shrink and swell, causing considerable density differences as the moisture content varies and cracks develop as the soil dries. This cracking condition has a detrimental effect on the stability of infrastructure built on expansive soil, such as road embankments. This paper investigates the influence of diatomaceous earth (at 5%, 10%, 15%, and 20% DE percent by mass) on the desiccation cracking of expansive soils. The report demonstrates an image analysis technique to describe soil surface cracking quantitatively. The geometric features of cracks, such as surface crack area and crack connectivity, were estimated and examined. The study considers soil crack area ratio and cracking index to investigate the effect of diatomaceous earth on expansive soil surface cracking. The crack area ratio and cracking index analysis results show that the expansive soil surface cracking is uneven and significant. The soil matrix containing 10% and 20% diatomaceous earth has reduced surface cracking and a homogenous radial cracking pattern. The image analysis approach, an essential method to quantitatively quantify soil desiccation cracking, revealed that diatomaceous earth substantially affects surface crack reduction.
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日南層群分布域の道路斜面の動態観測と地下水位推定による地すべり挙動の検討 査読あり
伊集院 弘尚, 福林 良典, 神山 惇, 末次 大輔
地盤工学会災害調査論文報告集 1 ( 1 ) 121 - 137 2023年4月
担当区分：最終著者 記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：公益社団法人 地盤工学会
イモ洗いのニホンザルが生息する宮崎県串間市の幸島から，南へ2.0kmほど国道448号を南下した箇所で，令和2年7月豪雨により路側構造物や道路に変状をきたす道路災害が発生した。当該箇所は，平成22年（2010年）から現在に至るまで，数回にわたり被災・復旧を繰り返している箇所であり国道448号の道路管理上の要ともいえる場所である。令和2年7月豪雨においては，擁壁の増し打ちアンカーの抜け出し，擁壁の傾倒・沈下，道路のクラック等の変状が確認され，全面通行止めによる通行規制が数か月間に渡り実施された。人的被害の発生は免れたものの，地域経済や観光業，緊急輸送道路としての機能に少なからず影響を与え，地域住民の生活に大きな制限を強いたことは言うまでもない。本事例報告においては，過去に発生した被災状況及び令和2年7月豪雨で発生した被災状況を紹介しながら，地盤工学的観点から，同じ箇所で繰り返し発生する道路災害防止に関しての1つの考えを述べるものである。
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宮崎県西米良村における国道219号線での道路盛土の崩壊と復旧工 査読あり
神山 惇, 福林 良典, 伊集院 弘尚, 末次 大輔
地盤工学会災害調査論文報告集 1 ( 1 ) 115 - 120 2023年4月
担当区分：最終著者 記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：公益社団法人 地盤工学会
令和2年7月豪雨により，宮崎県西米良村にある国道219号の道路盛土が崩壊した。当該現場は令和元年台風17号においても同様な被害が生じている。本稿では，令和2年7月豪雨における当該現場での被災状況調査結果について報告するとともに，過去の豪雨による被害事例について述べる。そして，今回の被害を受け設計，施工されている復旧工の様子を示す。
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Fukubayashi Y., Koyama A., Suetsugu D.
E3S Web of Conferences 368 2023年2月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：E3S Web of Conferences
In African countries, in order to improve the trafficability of earth and gravel road, locally available material-based and labour-based approach are regarded as one of the most practical measures. As one of the approaches, a base course reinforcement method using Do-nou, which is the Japanese term for soil bag, had been developed. In this study, the bearing capacity of base course built with Do-nou has been examined through the Dynamic Cone Penetration tests (DCP). The series of full-size driving tests have been conducted with varying base structures and compaction methods. The results of the DCP tests show that, only in the case of Do-nou reinforcement base with manual compaction, the strength distribution balance at the part of base course and subgrade within 800 mm in depth from surface was shifted from average to well after being subjected to traffic load. In the other two cases, the balance remained average. It presents that by reinforcing soil material with Do-nou bags, the base course compacted manually keeps the sufficient bearing capacity and well-balanced strength profile in depth comparing with those conventionally designed and constructed with equipment.
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Koyama A., Akira Y., Mitabe H., Fukubayashi Y., Suetsugu D.
Case Studies in Construction Materials 18 2022年12月
担当区分：責任著者 記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Case Studies in Construction Materials
The method of filling the lower space of a bridge with rigid polyurethane foam (RPU foam) to reduce the traffic load along with seismic reinforcement has rarely been applied to extend the life of bridges in Japan. This study evaluates the reinforcement effect and change in the vibration characteristics of a bridge converted into a lightweight embankment by RPU foam filling. A truck was driven on the bridge before and after the RPU foam filling. The vibration and strain of the slab were found to have reduced at the span center. When a traffic load was applied, the predominant frequency inside the RPU foam was ∼5 Hz, and long-period vibrations relative to the slab were confirmed.
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粘性土中に打設される木杭の鉛直支持力に及ぼす杭形状の影響 査読あり
末次 大輔, 那須 龍斗, 神山 惇, 福林 良典
土木学会論文集E2（材料・コンクリート構造） 77 ( 5 ) I_77 - I_83 2022年3月
担当区分：筆頭著者, 責任著者 記述言語：日本語 掲載種別：研究論文（学術雑誌）
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Performance of labor-intensive base course for gravel roads with application of Do-nou 査読あり
Fukubayashi Y., Koyama A., Suetsugu D.
Transportation Engineering 7 2022年3月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Transportation Engineering
Community participation in road construction and repair is necessary in improving rural roads in developing countries, more than 50% of which are in poor condition caused by less involvement by the government due to budget constraints. To promote community participation, constructing base course with do-nou, the Japanese term for soil bag, which does not require the use of compaction equipment, has been proposed as a practical method. To extend the application of this method, the method must be adopted by stakeholders and its performance must be clearly understood. In this study, to compare the performance of the base course constructed with do-nou with that of the conventional structures constructed with equipment based on the existing manual for low-volume roads, a series of full-size model driving tests were conducted. Silty sand with gravel was selected as the base course material that is locally available and can be practically used in rural areas of developing countries. The deformation of the base course reinforced with do-nou under traffic loading was 14.0%. By contrast, the deformation for the base course compacted with equipment was 4.9% and that for the base course compacted manually without reinforcement with do-nou was 20.9%. The results of a dynamic cone penetration survey revealed that encapsulating the base course material in do-nou bags efficiently converted the traffic load into compaction energy and thus developed a balanced strength profile. Base course reinforced with do-nou behaved as an aggregate of distinct elements of do-nou and transferred a smaller load to the subgrade when subjected to traffic loading compared with nonreinforced base courses compacted manually and with equipment. The base course with do-nou and manual compaction did not perform as well as the base course compacted with equipment; however, it demonstrated intermediate performance with surface settlement of less than the maximum allowable level of 50.8 mm. The thickness of the base course reinforced with do-nou can be determined according to the existing design manual. The degree of compaction of base course constructed labor-intensively is initially insufficient. Therefore, once the road is opened to traffic, traffic should pass over the entire width of the road in dry conditions to accelerate compaction and improve road performance.
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Koyama A., Suetsugu D., Fukubayashi Y., Mitabe H.
Construction and Building Materials 321 2022年2月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Construction and Building Materials
Frequent major earthquakes in Japan necessitate earthquake-resistant infrastructure. The dynamic deformation characteristics of rigid polyurethane foam, used as a lightweight embankment material, is examined in this study. The effect of the initial static stress on the shear modulus of single-layer samples was small, while the shear modulus of two-layer samples increased with increasing initial static stress. The damping ratio of single-layer samples converged to 4–5%, but decreased with increasing initial static stress up to 30 kPa in two-layer samples before increasing above 40 kPa. Results from cyclic uniaxial and triaxial tests were compared. The dynamic properties depended on restriction conditions and the deformation direction.
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Nakazawa H., Ishizawa T., Danjo T., Onoue Y., Suetsugu D., Hara T.
Lecture Notes in Civil Engineering 209 LNCE 56 - 67 2022年
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Lecture Notes in Civil Engineering
In this study, based on the damage survey in Nepal, shake table tests and rainfall experiments using a typical gabion retaining wall model were conducted to investigate the influence on earthquake and rainfall basically. In a series of experiments, two same models with retaining wall with slope ground same as typical gabion retaining wall in Nepal were constructed in rigid soil container. Then, the model experiments containing shake table test after preceding rainfall and rainfall after preceding shake table test were simultaneously performed in order to confirm difference of the damage aspects caused by pattern of earthquake and rainfall. As main results, it was confirmed that the deformation tendency of the gabion retaining wall was different by the order of rainfall and earthquake. Especially, the deformation of the retaining wall in Case of preceding shake table test was minor compared to preceding rainfall. Regardless of the order by rainfall and earthquake, the gabion retaining wall showed the same tendency on deformation mode.
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Deformation Resistance of the Gabion Retaining Wall Under Horizontal Loading 査読あり
Suetsugu D., Nakazawa H., Hara T., Fukubayashi Y., Koyama A.
Lecture Notes in Civil Engineering 209 LNCE 999 - 1007 2022年
担当区分：筆頭著者, 責任著者 記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Lecture Notes in Civil Engineering
This research investigated the effects of the connecting gabions, the packing density and the particle shape of the filling gravel, and the vertical pressure on the horizontal deformation resistance of the gabion retaining wall. The dimensions of the model gabion used in this experiment were 20 cm × 20 cm × 20 cm. The model gabion retaining wall was prepared by stacking three of them vertically. The horizontal loading tests were performed with a plane strain, in which a gabion in the middle of the retaining wall was pushed horizontally while applying constant vertical load. The obtained main findings are as follows. 1) The connecting gabions have the effect of increasing the deformation resistance due to the generation of tension in the gabion net due to the deformation of itself. 2) The particle shape of the filling gravel affects the deformation resistance of the gabion retaining wall. That is, the rigidity of the gabion retaining wall using the round gravel at a small deformation level was stiffer than in the case using the angular gravel. 3) The vertical stress acting on the gabion retaining wall has little influence on its deformation resistance.
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原 弘行, 藤江 佑大, 末次 大輔
土木学会論文集B3（海洋開発） 78 ( 2 ) I_571 - I_576 2022年
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：公益社団法人 土木学会
土にセメントを添加するとセメント水和物が間隙を充填するため，その透水性は未処理時に比べて著しく減少する．しかしながら，最近では海水の化学的浸食によってセメント水和物が崩壊することが指摘されている．そのため，海水が浸透すると固化処理土の透水性が変化することが懸念される．本研究では，セメント処理した砂質土に海水の代用としてMg水溶液を通水し，透水性の変化を調べた．その結果，セメント処理土の透水性は著しく低下することが明らかになった．併用した各種機器分析の結果から，Mg水溶液の浸透によるセメント処理土の透水性の低下は，処理土に浸透したMg塩によってセメント水和物の崩壊や水酸化マグネシウムの析出が起こり，通水前に比べて間隙容積が減少するとともに，浸透しにくい小さな径の間隙が増加したためと推定された．
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Koyama A., Fujimoto T., Suetsugu D., Fukubayashi Y.
Geomatics, Natural Hazards and Risk 13 ( 1 ) 1849 - 1866 2022年
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：Geomatics, Natural Hazards and Risk
Many heavy rain disasters have occurred in recent years in Japan. The maintenance of water storage facilities such as dams has become a global issue. The aim is to simulate the failure mechanism of reservoirs in which slip failure occurred on the downstream slope of the embankment due to the heavy rainfall in August 2019 in Japan. This study proposes a simulation method for evaluating embankment stability with respect to the fluctuations in the water level and the rainfall infiltration from the embankment surface using the two-dimensional saturated–unsaturated seepage flow simulation based on the finite element method. Moreover, the safety factors of the slip surface during heavy rain were calculated based on the simulated seepage line. By considering rainfall infiltration, the safety factor of the slip surface decreased significantly, and the occurrence of slip failure in the in-situ position could be reproduced. In conclusion, rainfall infiltration must be considered when evaluating the stability of a reservoir body during heavy rainfall.
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Dynamic properties of rigid polyurethane foam in cyclic triaxial tests 査読あり
Koyama A., Suetsugu D., Fukubayashi Y.
International Journal of GEOMATE 20 ( 82 ) 34 - 39 2021年6月
記述言語：英語 掲載種別：研究論文（学術雑誌） 出版者・発行元：International Journal of GEOMATE
The aim of this study is to clarify the dynamic properties of rigid polyurethane foam. A method for renovating a deteriorated bridge as a lightweight embankment was proposed. The space underneath a bridge is filled with polyurethane to support the upper structure. In this case, the upper structure of the bridge is considerably heavier than the polyurethane. Therefore, it is important to examine the seismic behavior of this new lightweight embankment. However, the dynamic deformation characteristics of polyurethane have not been clarified previously. In this study, stress-controlled cyclic triaxial tests based on JGS0542-2009 are used to evaluate the effect of the confining stress and the presence of a rigid layer on the dynamic properties of rigid polyurethane foam. As a result, the shear modulus of rigid polyurethane foam increases with increasing confining stress regardless of the absence of the rigid layer. The shear modulus of polyurethane with the rigid layer is lower than that of polyurethane without the rigid layer. The value of shear modulus of rigid polyurethane foam was measured in the range of approximately 1.6~3.2MPa. Moreover, the stiffness degradation and of rigid polyurethane foam are in good agreement with the Hardin-Drnevich model.
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Reconnaissance report on geotechnical damage caused by a localized torrential downpour with emergency warning level in Kyushu, Japan 査読あり
Toshifumi Mukunoki, Daisuke Suetsugu, Kazunari Sako, Satoshi Murakami, Yoshinori Fukubayashi, Ryohei Ishikura, Takenori Hino, Satoshi Sugimoto, Kota Wakinaka, Shinichi Ito, Atsushi Koyama
Soils and Foundations 61 ( 2 ) 600 - 620 2021年4月
記述言語：英語 掲載種別：研究論文（学術雑誌）
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令和2年7月九州豪雨による地盤災害特集号の追加報告について 査読あり
椋木 俊文, 末次 大輔, 酒匂 一成
地盤工学会災害調査論文報告集 1 ( 3 ) 333 - 333 2023年9月
記述言語：日本語 掲載種別：研究論文（学術雑誌） 出版者・発行元：公益社団法人 地盤工学会
本号は，令和5年4月1日に発刊された「地盤工学会災害調査論文報告集」創刊号の追加号である。「地盤工学会災害調査論文報告集」創刊号は，災害連絡会議から依頼を受けた企画であり，「令和2年7月九州豪雨による地盤災害調査報告書<sup>1)</sup>」をひな形にして，同災害の実態をアーカイブするための特集号として編集したものである。この調査報告書を作成した災害調査団の活動期間および報告集編集期間は，コロナ禍の状態であり，調査団間の連絡はメールが中心となった。また，越県調査も禁止していたため，調査団内に福岡-大分，長崎-佐賀，熊本-宮﨑-鹿児島の3つ領域ワーキンググループを作り，活動いただいた。調査団の中には，若手の研究者もいたことから，今後調査結果を論文発表したい可能性もあることを考慮し，この報告論文集への投稿については，あくまで調査団の意向ではなく各報告書の著者によるものとして公募した。ところが，一部で団員のメールアドレスが欠落していたことに気が付かれないまま，この企画が進められ，結果的に調査団員全員にこの方針がいきわたっていなかったことが，調査論文報告発刊後に判明した。本調査論文報告集の作成の意図が，調査結果を関係者の多くの方々に閲覧いただき，今後に役立ててもらうことが趣旨であることから，追加報告という形でも報告すべきであるという結論に至り，このような形で発刊させていただくこととした。今後の調査論文報告集については，調査団内での公募体制と形式を整えていただき，同様のことが起きないように留意いただきたい。最後に，追加発刊のためにご協力いただいた関係皆様には改めて御礼を申し上げる。
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令和2年7月九州豪雨による地盤災害特集号の発刊に際して 査読あり
椋木 俊文, 末次 大輔, 酒匂 一成, 若井 明彦
地盤工学会災害調査論文報告集 1 ( 1 ) 169 - 169 2023年
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神山 惇, 末次 大輔, 福林 良典
Construction and Building Materials 321 126377 2022年
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降雨浸透を考慮したため池堤体のすべり破壊に対する安定性評価手法の検討
宮崎睦士，神山 惇，末次大輔，福林良典，藤本哲生
令和2年度土木学会西部支部研究発表会 2021年3月
記述言語：日本語 掲載種別：研究論文（研究会，シンポジウム資料等）
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粘土地盤に打設された丸太継杭の鉛直支持力に及ぼす杭形状の影響
那須龍斗，末次大輔，神山 惇，福林良典
令和2年度土木学会西部支部研究発表会 2021年3月
記述言語：日本語 掲載種別：研究論文（研究会，シンポジウム資料等）