研究者詳細 - 野田　利弘

論文 - 野田　利弘

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Seismic stability assessment of a steel plate built-up column sited on a liquefiable soft ground

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

Proceedings of 5th International Workshop on New Frontiers in Computational Geomechanics, IWS-Brisbane 頁： 69-74 2010年5月

Seismic stability assessment of a lightweight structure on sandy/clayey foundations 査読有り

Nakai, K. and Noda, T.

Recent Developments of Geotechnical Engineering, Proc. of the 4th Japan-China Geotechnical Symposium 頁： 564-571 2010年4月

記述言語：英語

For a temporary structure, which is comparatively easy to placement and withdrawal, special countermeasures such as pile penetration or ground improvement are not taken into considerations. As a consequence, when an earthquake occurs during the placement/construction, personal injury might be caused by overturning of the temporary structure. In this paper, co- and post-seismic responses of interactive systems consisting of a temporary structure - alternately layered sandy/clayey foundations were numerically investigated by using a soil-water coupled elasto-plastic finite deformation analysis. The findings are mainly as follows. 1) An unstable structure such as temporary structure become at high risk of overturning by means of liquefaction of sand layer. 2) Although it is possible to consider countermeasure against overturning by widen the breadth and lower the height of the temporary structure, it turned out that installation of a construction board is very effective.

Predictive simulation of deformation and failure of peat-calcareous soil layered ground due to multistage test embankment loading

Takaine, T., Tashiro, M., Shiina, T., Noda, T., and Asaoka, A.

Soils and Foundations 50 巻 ( 2 ) 頁： 245-260 2010年4月

記述言語：英語掲載種別：研究論文（学術雑誌）

The continuous behaviour of a ground-embankment system from the stage of deformation up to failure was predicted with respect to an actual test embankment that had been constructed in stages on a soft ground made up of peat and calcareous soil. The behaviour prediction was carried out by employing soil-water coupled finite deformation analysis, which also included simulation of the embankment construction process. The information used in the analysis was limited to such things as the results of soil tests on soil materials (peat and calcareous soil) sampled from the ground, including their sensitivity ratios, and the embankment's construction history. The SYS Cam-clay model was used in the constitutive equations of the soils to determine the material constants of the soils and the initial conditions of the ground, and the computations were performed under plane strain conditions. As a result, the computed profiles of W-type ground settlement and of slip surfaces running through the embankment were found to be in good overall agreement with the actual profiles measured at the site. Furthermore, we found that this slippage is attributable to the undrained shear response of the soil elements in the calcareous soil layer, where slippage begins to occur during embankment loading. In other words, the slippage is caused by the rapid softening behaviour caused by the degradation of structure after the effective stress ratio reaches the vicinity of the critical state line.

Reproduction of a reclaimed ground considering its construction history and evaluation of its seismic behavior by using a soil-water coupled analysis 査読有り

Noda, T., Yamada, E., Nakano, M., Asaoka, A. and Sun, K.

Recent Developments of Geotechnical Engineering, Proc. of the 4th Japan-China Geotechnical Symposium 頁： 174-179 2010年4月

担当区分：筆頭著者記述言語：英語

The Nagoya port has reclaimed grounds of about 4500ha now, and has supported the economic activity of the postwar period of Japan. In the Chubu area including this Nagoya port, it is said that a trench type big earthquake occurs in high probability. In this paper, first, a reclaimed ground in the Nagoya port was reproduced numerically by using the geo-analysis code GEOASIA according to the construction history from the reclamation-by-drainage performed about 200 years ago to the present. In this calculation, the influence of the Tonankai earthquake which occurred in 1944 was also taken into consideration. Next, the Tonankai and Tokai linked-type earthquake assumed here from now on was inputted into this reclaimed ground by using the same analysis code in order to evaluate the co- and post-seismic behavior of the ground. The main findings from the results of the analysis were as follows. (1) In the linked-type earthquake assumed, liquefaction may occur even in diluvial sand layer whose N-values are comparatively large, and consolidation settlement of the layer may occur after the earthquake as well as the clay layer. (2) Quay wall may move about 3.5m horizontally to the sea side.

剛な構造物近傍の埋戻し地盤の地震時沈下挙動に関する遠心力模型実験とその数値シミュレーション査読有り

河井正，石丸真，野田利弘，浅岡顕

地盤工学ジャーナル 5 巻 ( 1 ) 頁： 45-59 2010年3月

記述言語：日本語掲載種別：研究論文（学術雑誌）

2007年新潟県中越沖地震の際，東京電力柏崎刈羽原子力発電所では，底面が岩着された原子炉建屋近傍で局所的に大きな埋戻し土の沈下が生じたことが報告されている。本研究では，剛な構造物近傍において，地震時にこのような大きな沈下が確認された例が少ないことを踏まえ，地盤の拘束圧を実物に近づけることが可能な遠心力模型実験によって現象を再現し，近傍地盤では，構造物から離れた地盤と同様の土の圧縮による沈下に加えて，壁面から地盤が離れる際に主働すべりによる沈下が生じていることを把握した。さらに，遠心力模型実験を対象にGEOASIA によるFE 解析を実施し，沈下現象の再現を試みた。その結果，解析結果において，地盤のダイレイタンシーに伴う土の圧縮による地盤の沈下が再現されており，構造物の近傍における上述の主働すべりによる大きな沈下も概ね再現可能であった。

練返し試料の圧縮曲線に及ぼす試料作製時の含水比の影響査読有り

田代むつみ，稲垣太浩，中野正樹，野田利弘，浅岡顕

地盤工学ジャーナル 5 巻 ( 1 ) 頁： 81-87 2010年3月

記述言語：日本語掲載種別：研究論文（学術雑誌）

自然堆積粘土の力学特性を把握するためには骨格構造概念が重要であり，骨格構造の働きを定量的・定性的に記述するためには，土台となる練返し試料による試験が必要不可欠である．本論文では，練返し試料の圧縮曲線に着目し，練返し時の含水比が及ぼす影響について検討した結果，以下の結論を得た．(1)液性限界よりも低い含水比で練り返した試料は，試料が固く練返しに大きな力を必要とするため過圧密土的な挙動を示す．(2)液性限界よりも高い含水比で練り返した試料は，構造が残存し嵩張った挙動を示す．(3)骨格構造を完全に喪失した練返し試料の作製に最も適した含水比は，液性限界である．

Proposal of a simple method for assessing the susceptibility of naturally deposited clay grounds to large long-term settlement due to embankment loading 査読有り

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

Soils and Foundations 50 巻 ( 1 ) 頁： 109-122 2010年2月

記述言語：英語掲載種別：研究論文（学術雑誌）

A simple method that utilizes the results of laboratory tests has been proposed for judging soft clay grounds that are susceptible to large residual consolidation settlement due to embankment loading. It was found that there is a possibility of large long-term settlement if the sensitivity and compression index ratios of the clay material that constitutes the ground are equal to or more than 8.0 and 1.5, respectively. The compression index ratio is defined in this paper as the ratio (Cc/Ccr) of the steepest gradient of the compression curve of an undisturbed sample to that of a remolded sample. Through the SYS Cam-clay model, an elasto-plastic constitutive model that describes the actions of the soil skeleton structure, it was found that clays with large sensitivity and compression index ratios are characterized by initially highly structured soils initially and that decay/upgradation of the structure can occur easily due to plastic deformation. In addition, by following Schmertmann's graphic method for the compression curves of in-situ compression curve(1953), this paper proposes a method of deducing the in-situ initial conditions from the results of laboratory consolidation tests on undisturbed samples. These investigations revealed not only that large delayed settlement is facilitated in clays that have high levels of structure and fast rates of structural decay, but also that the Δe method and other simple methods of predicting settlement may underestimate the amount of settlement.

*Co-seismic and post-seismic behavior of an alternately layered sand-clay ground and embankment system accompanied by soil disturbance 査読有り

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

Soils and Foundations 49 巻 ( 5 ) 頁： 739-756 2009年10月

Aiming at all soils all states all round geo-analysis integration 招待有り

Asaoka, A. and Noda, T.

International Symposium on Urban Geotechnics, Incheon, Korea 頁： 3-26 2009年9月

過圧密地盤の排水支持力解析査読有り

山田正太郎，野田利弘，浅岡顕

応用力学論文集，土木学会 12 巻頁： 247-254 2009年8月

飽和地盤に埋設されたダクト構造物の地震時挙動に関する数値シミュレーション査読有り

河井正，野田利弘，浅岡顕

応用力学論文集，土木学会 12 巻頁： 1021-1028 2009年8月

Evaluation of seismic performance of a box culvert buried in saturated sand with centrifuge and its numerical simulation 査読有り

Kawai, T., Noda, T. and Asaoka, A.

Proc. Int, Conf. on Performance-Based Design in Earthquake Geotechnical Engineering — from case history to practice —, IS-Tokyo 頁： 1087-1093 2009年6月

Coseismic and postseismic behavior of intermediate soil ground improved by sand compaction pile method 査読有り

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

Proc. Int, Conf. on Performance-Based Design in Earthquake Geotechnical Engineering — from case history to practice —, IS-Tokyo 頁： 1199-1205 2009年6月

Numerical analysis on deformation/failure patterns on embankments observed in 2004 Chuetsu earthquake 査読有り

Noda, T., Nakano, M., Asaoka, A., Yamada, E., Itabashia, K. and Inagaki, M.

Proc. Int. Symp. on Prediction and Simulation Methods for Geohazard mitigation, IS-Kyoto 2009 頁： 103-109 2009年5月

*Soil-water coupled finite deformation analysis based on a rate-type equation of motion incorporating the SYS Cam-clay model 査読有り

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

Soils and Foundations 48 巻 ( 6 ) 頁： 771-790 2008年12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）

This paper presents a new method of soil-water coupled finite deformation analysis of saturated soils that considers inertial forces. This method allows changes in the geometric shape of the soil to be taken into account and is capable of dealing with all types of external forces irrespective of whether they are static or dynamic. To be more specific, the paper describes the following points, which differ from the conventional methods: 1) the governing equations for saturated soil including the rate-type equation of motion containing a jerk term of the soil skeleton conforming to u-p formulation and updated Lagrangian, 2) derivation of a weak form of the rate-type equation of motion and discretization of the finite elements, and 3) use of the implicit time integration method for application of the conventional linear acceleration method (which assumes linear variation of acceleration) to the jerk term.
By mounting the elasto-plastic constitutive equation (SYS Cam-clay model), which can cover a wide range of soils and soil conditions, onto the above method of analysis, examples of simulation of dynamic/static triaxial laboratory testing of saturated soil specimens are described. The soil specimens were assumed to be medium dense sand under conditions of small-amplitude cyclic loading, partial drainage, and constant cell pressure. The simulation yielded the following results. (1) In the case of low frequencies, compaction occurs during loading and compression progresses over the entire specimen. (2) In the case of high frequencies, during loading and in the period in which wave propagation continues within the specimen after the end of loading, compaction occurs at the drained end of the specimen, whereas liquefaction occurs in its interior. After this stage, massive compression takes place within the specimen, leading to consolidation (consolidation after liquefaction).

Delayed failure of a clay foundation-embankment system after the occurrence of an earthquake 査読有り

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

Theoretical and applied mechanics JAPAN 57 巻頁： 41-47 2008年12月

Ground improvement of intermediate reclaimed land by compaction through cavity expansion of sand piles 査読有り

Nakano, M., Yamada, E. and Noda, T.

Soils and Foundations 48 巻 ( 5 ) 頁： 653-671 2008年10月

Numerical simulation of centrifugal model tests on seismic response of embankment-foundation systems

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

Proc. of 4th International Workshop on New Frontiers in Computational Geomechanics(IWS-Pittsburgh) 頁： 29-32 2008年10月

Post-seismic consolidation settlement of clayey soil due to the co-seismic disturbance

Noda, T., Takeuchi, H., Nakai, K., Nakano, M. and Asaoka, A.

Proc. of 4th International Workshop on New Frontiers in Computational Geomechanics(IWS-Pittsburgh) 頁： 57-60 2008年10月

Delayed failure of a clay foundation-embankment system after the occurrence of an earthquake

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

Proc. of 57th Japan national congress for theoretical and applied mechanics (Ed. Murakami,.A.) 頁： 41-47 2008年6月

担当区分：筆頭著者記述言語：英語

By using a soil-water coupled finite element method, deformation/failure behavior during and after the occurrence of an earthquake in a clay foundation-embankment system was numerically examined. The elasto-plastic constitutive model for the soil skeleton is the Super/subloading Yield Surface Cam-clay model. The embankment was calculated as a saturated soil. The results showed that the embankment maintained stability without any significant large deformation during the earthquake, while slip failure penetrating to the crest was suddenly generated a few hours after the earthquake.

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