Faculty Profiles - NODA, Toshihiro

Papers - NODA, Toshihiro

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Study on the pore water pressure dissipation method as a liquefaction countermeasure using soil-water coupled finite deformation analysis equipped with a macro element method Reviewed

Noda, T., Yamada, S., Nonaka, T. and Tashiro M.

Soils and Foundations Vol. 55 ( 5 ) page： 1130–1139 2015.10

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Numerical simulation of the pore water pressure dissipation method was performed using the GEOASIA soil-water coupled finite deformation analysis code, which is capable of accounting for inertial forces, together with the elasto-plastic constitutive SYS Cam-clay model based on the soil skeleton structure concept, with the goal of quantitatively assessing the effects of this method as a liquefaction countermeasure. At the same time, an effort was made to improve/enhance the calculation efficiency of the GEOASIA analysis code by incorporating a macro element method, which up to this point has only been applied to consolidation problems. The main findings of this study are as follows: 1) the macro element method is capable of highly accurate approximation even for dynamic problems; 2) it is capable of reproducing the pore water pressure increase suppression effect associated with the pore water pressure dissipation method, even when a relatively coarse mesh is used; 3) it is capable of reproducing the suppression of the decrease in effective stress due to the pore water pressure dissipation method, along with the resulting reduction in shear stiffness and lateral ground movement and settlement; and 4), it is possible to efficiently design the pore water pressure dissipation method by first performing calculations using a 1-D mesh to determine the effective drain spacing prior to performing calculations using 2-D or 3-D meshes.

DOI： http://dx.doi.org/10.1016/j.sandf.2015.09.013

Macro element method with water absorption and discharge functions for vertical drains Reviewed International journal Open Access

Yamada, S., Noda, T., Tashiro M. and Nguyen, H. S.

Soils and Foundations Vol. 55 ( 5 ) page： 1114–1129 2015.10

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

When simulating the vertical drain method using a soil-water coupled finite element analysis, a macro-element method can be used as a means of approximately applying the water absorption function of drains to individual elements. In this paper, the discharge function of vertical drains was added to the method by treating the water pressure in the drain as an unknown and adding a continuity equation for the drains to the governing equations. By extending the method in this way, the analytical results came to exhibit the well-resistance phenomenon automatically, depending on the analytical conditions. Numerical analyses were conducted after incorporating the proposed macro-element method into aquasi-static soil-water coupled elasto-plastic finite element method based on the finite deformation theory. The main conclusions are as follows:(1)the proposed method enables highly accurate approximations for problems involving material and/or geometrical nonlinearity and multilayered grounds; (2)the proposed macro-element method is capable of reproducing various phenomena that occur when the vacuum consolidation method is applied to a clayey ground containing a middle sand layer;(3)by following the formulation used in this paper,it is unnecessary to match the mesh division width to the drain arrangement and spacing. In addition, it is possible to obtain solutions that are minimally affected by the meshsize.

DOI： https://doi.org/10.1016/j.sandf.2015.09.012

Simulation and evaluation of improvement effects by vertical drains/ vacuum consolidation on peat ground under embankment loading based on a macro-element method with water absorption and discharge functions Reviewed International journal Open Access

Nguyen, H. S., Tashiro, M., Yamada, S. and Noda, T.

Soils and Foundations Vol. 55 ( 5 ) page： 1045 - 1058 2015.10

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

The authors previously extended themacro-element method proposed by Sekiguchi to include water absorption and discharge function sand incorporated this into a soil-water coupled finite deformation analysis code capable of accounting for inertial forces. The primary objective of this study is to validate the ability of the proposed method to simulate actual ground behavior by comparing the simulation results with the actual measurements of the embankment loading of a soft peat ground improved with vertical drain sand vacuum consolidation. It was found that the proposed method is capable of comprehensively and closely simulating not only the magnitude of settlement, but also various ground behaviors,
including the deformation of the surrounding ground and porewater pressure distributions. Furthermore, additional simulations were performed to elucidate the effect of a continuous middle sand layer found to exist and to span the entire improved area at an actual embankment site.

DOI： https://doi.org/10.1016/j.sandf.2015.09.007

Liquefaction countermeasures by shallow ground improvement for houses and their cost analysis Reviewed International journal

Tani, K., Kiyota, T., Matsushita, K., Hashimoto, K., Yamamoto, A., Takeuchi, H., Noda, T., Kiku, H. and Obayashi, J.

Soil Dynamics and Earthquake Engineering Vol. 79 ( Part B ) page： 401–414 2015.8

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

A large number of houses suffered from liquefaction-induced damages in recent large earthquakes due to lack of economical countermeasures. In this study, the shallow ground improvement, up to several meters deep, was proposed as an economical liquefaction countermeasure for houses. Based on the case studies, the design criteria of allowable tilt angles and penetration settlements of houses were proposed for the required level of serviceability against moderate and large earthquakes. The results of questionnaire survey, airborne LiDAR survey, and centrifuge model tests demonstrated that even a few meters of non-liquefiable layers in shallow ground could greatly reduce settlements and tilting of houses. A series of numerical analyses indicated that non-liquefiable layer of three meters thick below ground water table improved by solidification methods can prevent significant damages of houses. Furthermore, cost analyses were carried out for different ground improvement methods for both new and existing houses.

DOI： https://doi.org/10.1016/j.soildyn.2015.08.016

Simulation of large-scale deformation of ultra-soft peaty ground under test embankment loading and investigation of effective countermeasures against residual settlement and failure Reviewed Open Access

Tashiro, M., Nguyen, H. S., Inagaki, M., Yamada S. and Noda, T.

Soils and Foundations Vol. 55 ( 2 ) page： 343-358 2015.4

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

The construction of a test embankment on ultra-soft ground containing an approximately 50-m-deep soft peat layer with N-values of 0 to 1 did not result in catastrophic slip failure during construction but did cause substantial deformation of the adjacent ground. In addition, large-scale settlement in excess of 11 m occurred in the approximately 3 years following embankment construction. Based on field observations, it became evident that this large settlement was attributable to delayed compression of the deep peat layer, which was assumed at the design stage not to be subject to settlement. Based on laboratory tests and site investigations, it was deduced that due to depositions under continuous artesian conditions, this peat layer had an extremely low consolidation yield stress and was in a state such that even a slight increase in stress would result in large-scale compression. After confirming the ability of the analysis code based on soil-water coupled finite deformation theory, which included an elasto-plastic constitutive equation describing the behavior of the soil skeleton, to reproduce the observed ground behavior, the code was used to predict future settlement. These simulations were then used to evaluate the effectiveness of countermeasures aimed not only at improving stability during construction, but also at reducing residual settlement. The results of these analyses were applied in the planning of large-scale repair work performed on the test embankment. Also, when an embankment was subsequently constructed near the test embankment on similar ultra-soft ground, ground improvements were conducted prior to embankment construction as a countermeasure against residual settlement. In this paper, valuable field data related to these latter construction efforts is also presented.

DOI： http://dx.doi.org/10.1016/j.sandf.2015.02.010

*Soil-water-air coupled finite deformation analysis based on a rate-type equation of motion incorporating the SYS Cam-clay model Reviewed Open Access

Noda, T. and Yoshikawa, T.

Soils and Foundations Vol. 55 ( 1 ) page： 45-62 2015.2

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

With the aim of expanding the soil skeleton-water coupled finite deformation analysis code mounted with the SYS Cam-clay model and capable of accommodating inertia forces to deal seamlessly with soils from the unsaturated to the saturated states, a new soil skeleton-water-air coupled finite deformation analysis method (u-pw-pa-sw formulation) based on the three-phase mixture theory was proposed. The following are the main observations obtained through computations performed under simple conditions using this new method. (1)Simulation of constant cell pressure undrained (and unexhausted) triaxial tests on dense sand specimens with a degree of saturation of 99.9%, which in reality could be considered to be 'saturated soil,' was carried out. It was shown that when the back pressure was not sufficiently large, the existence of air causes desaturation to take place due to the effect of volumetric expansion and no increase in the deviator stress is observed. It was confirmed that the results of this simulation agreed with experimental results. (2)Unlike the conventional method of analysis in which the degree of saturation is not explicitly made an unknown, the current method of analysis, in which the degree of saturation is explicitly made an unknown (u -pw -pa -sw formulation), was shown to be capable of expressing the increase in the degree of saturation even in the case of insular air saturation when the suction is 0.

DOI： http://dx.doi.org/10.1016/j.sandf.2014.12.004

Resilient breakwater foundation against level II earthquake and tsunami

Hazarika, H., Chaudhary, B., Monji, N., Ishikura, R., Kasama, K., Hara, T., Yamazaki, N, Noda, T. and Yamada, S.

The 6th International Geotechnical Symposium on Disaster Mitigation in Special Geoenvironmental Conditions page： 35-46 2015.1

浅層盤状改良工法による戸建て住宅の液状化被害軽減効果の検証と経済性評価 Reviewed Open Access

谷　和夫，松下克也，橋本隆雄，山本彰，竹内秀克，野田利弘，規矩大義，大林淳，清田隆

地盤工学ジャーナル Vol. 9 ( 4 ) page： 533-553 2014.12

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

2011年東北地方太平洋沖地震により発生した地盤の液状化により、数多くの戸建て住宅が被害を受けた。本研究では、戸建て住宅を対象とした経済的な液状化対策として、浅層盤状改良工法の適用の可能性について検討した。既往の研究と同地震による戸建て住宅の液状化被害を調査し、液状化に対する戸建て住宅に要求される性能として、その傾斜角を、中地震では10/1,000（めり込み沈下量10cmに相当）以下、大地震では16.7/1,000（めり込み沈下量15cmに相当）以下とすることが適切であることを示した。また、被害調査と遠心模型実験を通じて、浅層盤状改良工法による液状化対策の効果を明らかにした。そして、一連の数値解析により、表層地盤の固化工法による地盤改良層厚を3m以上とすることで、液状化に対する戸建て住宅の要求性能を満足することを示した。さらに、浅層盤状改良工法の種類と改良深度、改良面積をパラメータとした経済性評価を行い、同工法の設計に有益な情報を提供した。

DOI： http://dx.doi.org/10.3208/jgs.9.533

Open Access

Numerical analysis of improvement effect on peaty ground by vertical drain/ vacuum consolidation based on a new macro-element method Reviewed

Nguyen, H.S., Tashiro, M., Noda, T. and Yamada, S.

The 14th International Conference of the International Association for Computer Methods and Advances in Geomechanics (14IACMAG) page： 1145-1150 2014.9

Seismic response analysis of river embankments constructed on alternatively layered soft ground Reviewed

Noda, T., Nakai, K. and Kato, K.

The 14th International Conference of the International Association for Computer Methods and Advances in Geomechanics (14IACMAG) page： 761-766 2014.9

Evaluation of seismic behavior of model earth dams in the geotechnical centrifuge Reviewed

Kawai, T., Ishimaru, M. and Noda, T.

The 14th International Conference of the International Association for Computer Methods and Advances in Geomechanics (14IACMAG) page： 767-772 2014.9

Soil-water coupled finite deformation analysis on subgrade reaction force acting on the underground pile Reviewed

Nakai, K., Noda, T., Komura, S. and Shiratori, Y.

The 14th International Conference of the International Association for Computer Methods and Advances in Geomechanics (14IACMAG) page： 997-1000 2014.9

Verification of a new soil-water-air coupled analysis based on a rate-type equation of motion through realization of uniform deformation of an unsaturated soil specimen Reviewed

Noda, T. and Yoshikawa, T.

UNSAT2014: Unsaturated Soils: Research & Applications page： 613-619 2014.7

Numerical simulation of mechanical behavior of a triaxial silty soil under undrained and various controlled air boundary conditions Reviewed

Yoshikawa, T. and Noda, T.

UNSAT2014: Unsaturated Soils: Research & Applications page： 589-595 2014.7

Simulation of well resistance of vertical drains using new macro element method

Nguyen, H.S., Yamada, S., Noda, T. and Tashiro, M.

COMPSAFE: Computational Engineering and Science for Safety and Environmental Problems page： 164-167 2014.4

Seismic response analysis of river embankments constructed on the alternatively layered soft ground

Nakai, K., Noda, T. and Kato, K.

COMPSAFE: Computational Engineering and Science for Safety and Environmental Problems page： 140-143 2014.4

Seismic and postseismic behavior of river levee on soft clay ground Invited

Kodaka, T., Noda, T., Yoshikawa, T. and Takaine, T.

COMPSAFE: Computational Engineering and Science for Safety and Environmental Problems page： 138-139 2014.4

A 3D soil-water coupled FE analysis of hollow cylinder test concerning non-uniform deformation Reviewed Open Access

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

Soils and Foundations Vol. 53 ( 6 ) page： 923-936 2013.12

Realization of uniform deformation of soil specimen under undrained plane strain condition based on soil-water coupled finite deformation analysis considering inertia forces Reviewed Open Access

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

Soils and Foundations Vol. 53 ( 6 ) page： 937-950 2013.12

Acceleration generation due to strain localization of saturated clay specimen based on dynamic soil-water coupled finite deformation analysis Reviewed Open Access

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

Soils and Foundations Vol. 53 ( 5 ) page： 653-670 2013.10

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Papers - NODA, Toshihiro