研究者詳細 - 野田　利弘

論文 - 野田　利弘

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Damage statistics (Summary of the 2011 off the Pacific Coast of Tohoku Earthquake Damage) 査読有り

Kazama, M. and Noda, T.

Soils and Foundations 52 巻 ( 5 ) 頁： 780-792 2012年10月

An attempt to replicate the so-called 'trampoline effect' in computational geomechanics

Asaoka, A., Sawada, Y., Noda, T., Yamada, S. and Shimizu, R.

Proceedings of l5th World Conference on Earthquake Engineering 頁： 1817 2012年9月

記述言語：英語

In this research, we reproduced the vertical asymmetrical acceleration response observed at the ground surface at KiK-net measurement station IWTH25 (West Ichinoseki) during the 2008 Iwate-Miyagi earthquake using the finite deformation analysis code GEOASIA, which employs an elasto-plastic constitutive equation, the SYSCam-clay model, that incorporates the concept of soil skeleton structure. Also, it was found that the asymmetrical acceleration motions in the vertical direction measured at the ground surface at this location can be caused by a ground uplift phenomenon associated with loosening of heavily overconsolidated soils.

Overview of the geotechnical damages and the technical problems posed after the 2011 off the Pacific Coast of Tohoku Earthquake 査読有り

Kazama, M., Noda, T., Mori, T. and Kim, T.

Geotechnical Engineering Journal of the SEAGS & AGSSEA 43 巻 ( 2 ) 頁： 49-56 2012年6月

SPH method with an elasto-plastic constitutive model taking account of soil skeleton structure at work

Nonoyama, H., Masaki, N. and Noda, T.

Proceedings of 6th International Workshop on New Frontiers in Computational Geomechanics 頁： 45-48 2012年5月

The effect of stratigraphic composition and dip of deeper layer on the occurrence of subsurface liquefaction

Nakai, K., Noda, T. and Asaoka, A.

Proceedings of 6th International Workshop on New Frontiers in Computational Geomechanics 頁： 173-176 2012年5月

A three-dimensional analysis of gas-governor located on a liquefiable soft ground

Takaine, T., Xu, B., Nakai, K. and Noda, T.

Proceedings of 6th International Workshop on New Frontiers in Computational Geomechanics 頁： 177-182 2012年5月

A preliminary simulation of undrained hollow cylinder torsional test on saturated overconsolidated clay

Xu, B., Nakai, K., Noda, T. and Asaoka, A.

Proceedings of 6th International Workshop on New Frontiers in Computational Geomechanics 頁： 177-182 2012年5月

Inertia effect on deformation and subsequent triggered acceleration during shear band in overconsolidated clay

Noda, T., Xu, B. Nakai, K. and Asaoka, A.

Proceedings of 6th International Workshop on New Frontiers in Computational Geomechanics 頁： 39-44 2012年5月

Numerical simulation of failure behavior of naturally deposited clay soil with dynamic motion

Yamada, S., Noda, T. and Asaoka, A.

Proceedings of 6th International Workshop on New Frontiers in Computational Geomechanics 頁： 165-168 2012年5月

Anti-seismic mechanism of a sandy ground improved by SCP method 査読有り

Noda, T., Asaoka, A., and Takeuchi, H.

Proc. of 14th Asian Regional Conf. on Soil Mechanics and Geotechnical Engineering (14th ARC) 頁： 273 2011年5月

担当区分：筆頭著者記述言語：英語

Anti-seismic mechanism of typical loose sandy ground improved by the sand compaction pile (SCP) method was investigated using the geo-analysis code GEOASIA, which is a dynamic/static soil-water coupled finite element deformation analysis code incorporating the SYS-Cam clay model as a constitutive model of the soil skeleton. The mechanism was evaluated on the two types of earthquakes, i.e., the so-called Level 1 (L1) and Level 2 (L2) earthquake motions under 2-dimensional plane strain conditions. The main conclusions are drawn as follows. (1)Compared with untreated grounds, the deformation caused by earthquakes is suppressed in the SCP-improved grounds, both L1 and L2 earthquake motions. (2)Stress concentration occurs at the sand piles because the sand element at the piles exhibits hardening behavior due to plastic expansion.

Numerical study on the seismic assessment of coastal reclaimed ground 査読有り

Nakai, K., Noda, T. and Asaoka, A.

Proc. of 14th Asian Regional Conf. on Soil Mechanics and Geotechnical Engineering (14th ARC) 頁： 278 2011年5月

記述言語：英語

Seismic behavior of a coastal artificial reclaimed ground within the Port of Nagoya and antiseismic effects of two types of ground strengthening techniques were evaluated through numerical analysis. Use of the program GEOASIA for the numerical analysis enabled precise modeling of the targeted ground and consistent analyses of the pre-seismic, co-seismic, and post-seismic behaviors. Main findings are as follows. 1)Loose sand layers were subjected to large amount of lateral flow due to liquefaction during the earthquake, which led in turn to extensive damage to the revetment constructed on the reclaimed ground. 2) Steel pipe sheet pile cofferdam method is unlikely to be effective because the bending moment loaded on the steel pipes will exceed the yield stress during the earthquake. 3) Ground improvement using a jet grouting method will not contribute to damage reduction in the revetment area, but should drastically reduce the ground deformation around the improvement area.

Prediction of Settlement in Natural Deposited Clay Ground with Risk of Large Residual Settlement due to Embankment Loading 査読有り

Tashiro, M., Noda, T., Inagaki, M., Nakano, M. and Asaoka, A.

Soils and Foundations ５１巻 ( １ ) 頁： 133-149 2011年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

This study endeavors to predict the settlement that could occur in the future at a site where settlement due to embankment loading is already occurring at present. In the site studied here, large residual settlement of as much as 70 cm has already occurred in the 4 years since it entered into service. It is believed that settlement will also continue in the future because excess pore pressure is still present within the clay layers. Furthermore, according to the method of evaluation proposed previously by the authors, which is based on the sensitivity and compression index ratios, it can be judged that the ground includes clays that are sensitive to disturbance and have a strong possibility of large residual settlement. In this paper, simulation of the settlement observed up to now at the site as well as prediction of the settlement that could occur in the future was carried out by deducing the higher compressibilities possessed by the in-situ clays compared with the undisturbed clay specimens in the laboratory. The soil-water coupled finite deformation analysis was employed using the analysis program GEOASIA, in which the constitutive equation for the soil skeleton is mounted with the SYS Cam-clay model. In addition, the effect of modifying the vertical section of the embankment by overlaying in order to counter the settlement was also investigated by numerical analysis. The results showed that such a countermeasure cannot be expected to lead to faster consolidation and that it may require massive funding over a long period of time to cover the maintenance and management costs involved.

DOI： 10.3208/sandf.51.133

総説：巨大地震に備えるための現代地盤力学の役割招待有り

野田利弘

電力土木 ( 356 ) 頁： 6-11 2011年1月

記述言語：日本語掲載種別：研究論文（学術雑誌）

人工島・海上人工埋立地に生活・経済基盤を依拠する我が国にとって，切迫する巨大地震に対する人工地盤の耐震性再評価や耐震強化は喫緊の課題である。しかし，人工地盤の大半が粘土でも砂でもない細粒分を多く含んだ中間土からなるが，このことだけを取りあげても，砂だけ，粘土だけを対象にするような要素研究の細分化が進んだ近代土質力学的視野では対応できない。要素を統合的・俯瞰的視野で捉える新しい現代地盤力学の進展とその成果の工学への還元こそが必要となる。本稿では，この観点から近代土質力学の課題と現代地盤力学の役割について述べる。

軟弱地盤上に設置した仮設構造物の地震時安定性評価と転倒防止対策の一検討査読有り

中井健太郎, 野田利弘

地盤工学ジャーナル 5 巻 ( 3 ) 頁： 499-510 2010年9月

記述言語：日本語掲載種別：研究論文（学術雑誌）

比較的簡単に設置・撤去ができる仮設構造物は，設置期間が短いものの，杭の設置や地盤改良など特段の対策が施されないため，施工・設置中に地震が発生した場合，転倒による人身被害等が懸念される。本論文では，2 種類の軟弱地盤（砂質地盤および粘性土地盤）上に建設された仮設構造物の地震時安定性を数値解析的に検討した。その結果，仮設構造物転倒の主たる原因は，単に加速度の増幅（最大加速度）ではなく，①仮設構造物の固有振動数と地盤の卓越振動数の一致に伴う揺れの増幅と，②表層地盤の液状化による支持力低下とそれに伴う構造物の不同沈下にあることがわかった。転倒防止対策としては，仮設構造物の幅と高さを変えることによって，構造物の固有振動数と地盤の卓越周波数を一致させないことも重要であるが，仮設構造物直下に敷設板を用いて構造物と地盤との設置面積を大きくすることが，簡単で効果的な対策となることがわかった。

部分的に固化改良したゆるい砂地盤の地震時／地震後応答解析査読有り

竹内秀克, 中井健太郎, 野田利弘

応用力学論文集，土木学会 13 巻頁： 443-452 2010年8月

記述言語：日本語掲載種別：研究論文（学術雑誌）

本論文では，薬液注入・高圧噴射等のセメント固化改良工法等により，部分的あるいは離散的に改良固化が施された砂質地盤を想定して，地震を受ける場合の変形抑止効果を数値解析的に調べた．解析は土骨格の弾塑性構成式にSYSカムクレイモデル3)4)を用いた水～土連成動的／静的有限変形計算コード（GEOASIA）5)6)により行い，改良砂質地盤の地震中および地震後の挙動を調べた．また定性的ではあるが，系統的な結果を得るために規則的に改良体を配置し，実スケールにて解析を実施して，改良部が周辺地盤に与える影響も調べた．

Seismic response analysis of a coastal artificial reclaimed ground containing a soft layer 査読有り

Noda, T., Nakai, K. and Asaoka, A.

IOP Conference Series: Materials Science and Engineering, Vol.10, Proceedings of 9th World Congress on Computational Mechanics and 4th Asian Pacific Congress on Computational Mechanics CD, No.012107 巻頁： 19-23 2010年7月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

The seismic resistance of a coastal artificial ground situated within the Port of Nagoya against the Tokai-Tonankai-Nankai triple-segment earthquake was assessed. The analysis was carried out using the elasto-plastic constitutive equation for soils (SYS-Cam clay model) mounted on the soil-water coupled finite element deformation analysis program The model focuses attention on the action of the soil skeleton structure, and the analysis allows description of the mechanical behavior of a wide range of soils without distinguishing between static and dynamic behavior. When considering earthquake damage, attention usually tends to focus only on the phenomenon of liquefaction in sandy grounds. In this paper, finite element analysis was employed to simulate the phenomenon of liquefaction of soft sand and, in addition, to show that because of disturbance of the soil during the earthquake, there is a danger of large settlement occurring over a long period after the earthquake in the soft clay layer directly beneath the area that is under the action of vertical loads.

Different failure modes of a clay foundation-embankment system corresponding to different incident seismic waves 査読有り

Nakai, K., Noda, T., and Asaoka, A.

Geotechnical Special Publication No.201, Soil Dynamics and Earthquake Engineering, ASCE 頁： 125-130 2010年6月

記述言語：英語掲載種別：研究論文（学術雑誌）

In recent years, damage to embankments from earthquakes has been frequently reported. In this paper, the deformation and failure behavior of an embankment constructed on a weak clay foundation during and after an earthquake is investigated using numerical analysis, GEOASIA, assuming a 40 g centrifugal field. The main conclusions obtained were as follows. 1) Although the embankment remained stable without large deformation during the earthquake, a slip plane subsequently penetrated through the embankment, resulting in delayed failure (circular arc slip). 2) The deformation behavior (failure mode) of the foundation and embankment varies greatly depending on the characteristics of the incident seismic motions.

Modeling and seismic response analysis of a reclaimed artificial ground 査読有り

Noda, T., Asaoka, A. and Nakai, K.

Geotechnical Special Publication No.201, Soil Dynamics and Earthquake Engineering, ASCE 頁： 294-299 2010年6月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Compared with natural grounds formed by sedimentation over many years, reclaimed artificial grounds are often weak. In this work, modeling of a reclaimed offshore artificial ground and its seismic response analysis were carried out, and the vulnerability of the weak reclaimed layers to seismic activity is pointed out. This study was carried out using a soil-water coupled finite deformation analysis program GEOASIA incorporating an elasto-plastic constitutive model (the SYS Cam-clay model). This model is capable of describing, within a single framework, the behaviors of sands, clays, and intermediate soils consisting of sand/clay mixtures through their soil skeleton structures (structure, overconsolidation, anisotropy) and its works. In reclaimed sand, lateral flow and upward lifting of lightweight underground structures occur because of liquefaction during an earthquake. In reclaimed clay, long-term settlement, which continues for several years after the earthquake, occurs.

Numerical analysis on co- and postseismic behavior of sandy/clayey soil ground improved by sand compaction pile method 査読有り

Takeuchi, H., Noda, T., and Asaoka, A.

Geotechnical Special Publication No.201, Soil Dynamics and Earthquake Engineering, ASCE 頁： 218-224 2010年6月

記述言語：英語掲載種別：研究論文（学術雑誌）

The co- and postseismic behaviors of typical loose sandy ground and soft clayey ground improved by the sand compaction pile (SCP) method were investigated using a soil-water coupled finite element deformation analysis program incorporating the SYS-Cam clay model. The results indicated that the deformation caused by earthquakes was suppressed in the SCP improved grounds, irrespective of whether they were sandy or clayey. Although the surrounding ground was liquefied in the case of SCP-improved sandy ground, the confining pressure was maintained in the SCP interpile zone because of the compaction effect produced by the cavity expansion of the sand piles. In the case of the SCP-improved clayey ground, negative excess pore pressures appeared in the SCP sand piles because of the hardening that results from plastic expansion and stress was concentrated on them.

Soil-water coupled finite deformation analysis of seismic deformation and failure of embankment on horizontal and inclined ground 査読有り

Nakano, M., Sakai, T., Noda, T., and Asaoka, A.

Geotechnical Special Publication No.201, Soil Dynamics and Earthquake Engineering, ASCE 頁： 139-144 2010年6月

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