Faculty Profiles - NODA, Toshihiro

Papers - NODA, Toshihiro

Division display 101 - 120 of about 214 ／ All the affair displays >>

Simulation of delayed failure in naturally deposited clay ground by soil-water coupled finite deformation analysis taking inertial forces into consideration Reviewed

Yamada, S. and Noda, T.

Proceedings of the 18th International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013 page： 841-844 2013.9

Oscillation of acceleration accompanying shear band and subsequent time-dependent behavior in overconsolidated clay under undrained plane-strain conditions Reviewed

Noda, T. and Xu, B.

Proceedings of the 18th International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013 page： 403-406 2013.9

Excavation analysis of ground using SPH method Reviewed Open Access

Vol. 16 page： I_341-I_350 2013.9

Language：Japanese Publishing type：Research paper (scientific journal)

In order to solve large deformation problem of geomaterials, the SPH method is used which is
a kind of particle method based on the meshless Lagrangian scheme. The method can solve large deformation problems without mesh distortion. Moreover, it can handle the governing equations and existing constitutive models for geomaterials based on a continuum mechanics. To express various states of the soil, the elasto-plastic constitutive model taking account of soil skeleton structure is introduced into the method. In this paper, in order to verify the numerical scheme, a simulation of simple shear test is carried out. The obtained results are compared with theoretical solutions. Furthermore, the excavation problems for loose and dense sand ground are solved. From a series of the numerical results, the effectiveness of the method with the constitutive model of high performance is demonstrated.

DOI： 10.2208/jscejam.69.i_341

Open Access

Influence of brittle property of cement treated soil on undrained bearing capacity characteristics of the ground Reviewed

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

Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol. 44 ( 3 ) page： 84-93 2013.9

Language：English Publishing type：Research paper (scientific journal)

In this study, the influence of brittle property of geomaterials on the failure behavior of the ground in an undrained bearing capacity problem was investigated numerically from the standpoint of taking the brittle behavior of cement treated soil as softening behavior of the soil element. The numerical analyses were performed using the soil-water coupled finite deformation analysis code GEOASIA mounted with the SYS Cam-clay model, which describes the soil skeleton structure at work. Cement treated ground and naturally deposited clay ground were modelled and compared, and it was found that they showed widely differing failure processes depending on differing initial conditions. Especially, it was found that when progressive failure in which strain localization region develops due to propagation of material failure occurs, even though the ground is composed of brittle materials such as cement treated soil, those brittle properties do not directly manifest in the load-settlement relationship. Additionally, the investigation revealed that, since every soil element on the slip lines does not reach its peak strength simultaneously when progressive failure occurs, post-peak material properties, i.e. the ratio of residual strength to peak strength and softening rate from peak to residual state, affect the bearing capacity of the ground.

ゆるい砂地盤における砂圧入締固めによる周辺地盤への3次元影響評価解析 Reviewed Open Access

竹内秀克，河村精一，野田利弘，浅岡顕

地盤工学ジャーナル Vol. 8 ( 2 ) page： 239-249 2013.6

Language：Japanese Publishing type：Research paper (scientific journal)

「砂圧入式静的締固め工法」は，地盤中に流動化砂を圧入・押し広げることにより，周辺地盤に強制的に圧縮・せん断を与え，締固め効果を期待する工法である。工法の性格上，地盤に変位や応力を与えることに伴い，近接の既設構造物に少なからず影響を及ぼす。この影響の程度を予測／評価するためには，土要素の平均有効応力変化に伴う圧縮挙動だけでなく，せん断応力に伴うダイレイタンシー挙動もより精度よく評価する必要がある。本研究では，自然粘土～中間土～砂を一貫して説明することが可能な弾塑性構成式(SYSカムクレイモデル)を搭載する水～土連成有限変形解析を用い，3次元条件で砂圧入締固めの過程を再現して解析を実施した。この結果，砂圧入式静的締固め施工時の，周辺砂地盤の地表面および地中発生変位の距離に伴う減衰(距離減衰)や，近接構造物に与える地盤反力(側圧)分布は施工位置からの距離に応じて減少することがわかった。

DOI： 10.3208/jgs.8.239

Open Access

Damage statistics (Summary of the 2011 off the Pacific Coast of Tohoku Earthquake Damage) Reviewed Open Access

Kazama, M. and Noda, T.

Soils and Foundations Vol. 52 ( 5 ) page： 780-792 2012.10

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 page： 1817 2012.9

Language：English

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 Reviewed

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

Geotechnical Engineering Journal of the SEAGS & AGSSEA Vol. 43 ( 2 ) page： 49-56 2012.6

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 page： 45-48 2012.5

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 page： 173-176 2012.5

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 page： 177-182 2012.5

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 page： 177-182 2012.5

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 page： 39-44 2012.5

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 page： 165-168 2012.5

Anti-seismic mechanism of a sandy ground improved by SCP method Reviewed

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

Proc. of 14th Asian Regional Conf. on Soil Mechanics and Geotechnical Engineering (14th ARC) page： 273 2011.5

Authorship：Lead author Language：English

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 Reviewed

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

Proc. of 14th Asian Regional Conf. on Soil Mechanics and Geotechnical Engineering (14th ARC) page： 278 2011.5

Language：English

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 Reviewed

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

Soils and Foundations Vol. ５１ ( １ ) page： 133-149 2011.2

Language：English Publishing type：Research paper (scientific journal)

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 Invited

野田利弘

電力土木 ( 356 ) page： 6-11 2011.1

Language：Japanese Publishing type：Research paper (scientific journal)

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。

A means for assessing the seismic stability of a temporary structure sited on soft ground and preventing its collapse Reviewed Open Access

Kentaro NAKAI and Toshihiro NODA

Vol. 5 ( 3 ) page： 499-510 2010.9

Language：Japanese Publishing type：Research paper (scientific journal)

While a temporary structure is relatively simple to erect and remove, the fact that no particular measures such as pile installations or soil improvements are taken for its protection can mean that there is a risk of it collapsing in the event of an earthquake. This paper reports a numerical analysis of the seismic stability of a temporary structure erected on a foundation of alternating clay and sand layers in a case where the surface layer is sandy and clayey. It finds that the main cause for the structure's collapse lies in 1) the increase in the amplitude of the tremors resulting from a coincidence of the predominant ground wave motion with the specific vibration of the structure, and 2) the decline in
the bearing force and the consequent unevenness in the settlement of the structure as a result of liquefaction in the surface sand layer. One important prevention measure is to ensure that the specific vibration does not coincide with the predominant ground motion by making appropriate changes in the height and width of the structure; but another
cheap but effective safeguard is to increase the area of contact between the structure and its foundation by laying a base immediately below the temporary structure.

DOI： 10.3208/jgs.5.499

Open Access

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 Reviewed

竹内秀克, 中井健太郎, 野田利弘

応用力学論文集，土木学会 Vol. 13 page： 443-452 2010.8

Language：Japanese Publishing type：Research paper (scientific journal)

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．

　 PREV - NEXT 　

<NODA, Toshihiro>

Papers - NODA, Toshihiro