Faculty Profiles - NODA, Toshihiro

Papers - NODA, Toshihiro

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New developments related to clarification of the mechanisms of ground deformation caused by earthquakes - In the wake of the Great East Japan Earthquake - Invited Reviewed

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

Journal of JSCE Vol. 5 ( 1 ) page： 133-144 2017.3

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

The 2011 Great East Japan Earthquake caused massive ground damage, including liquefaction of sandy grounds, collapse of river levees and lands developed for housing, etc., particularly in regions across eastern Japan. Not only damage to 'currently unqualified' structures that did not conform to existing design standards and codes but also ground damage that could not be explained within the framework of conventional geomechanics and geotechnical engineering was observed. Particularly in the latter case, therefore, it has become necessary to develop new techniques in geomechanics without being restrained by the conventional framework. From the above standpoint, this paper reviews the research that has been carried out in the field of geotechnology after the Great East Japan Earthquake. More specifically, new knowledge relating to the mechanism of liquefaction damage at Urayasu City and other ground deformation caused by the earthquake is introduced, together with the results of research carried out on ground strengthening techniques.

DOI： 10.2208/journalofjsce.5.1_133

地盤－煙突構造物相互作用系の耐震性に及ぼす入力地震波の影響 Reviewed

中井健太郎，野田利弘

土木学会論文集 A2(応用力学) Vol. 73 ( 2 ) page： I_409-I_418 2017.1

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

本論文では，液状化危険度の高い地盤上に実在する煙突を対象に，二次元平面ひずみ条件下での地震応答解析を実施し，地盤－構造物相互作用系における耐震性評価を行った．その結果，地震波が構造物の固有周期帯を多く含んでいると，共振によって構造物の揺れが大きくなることに加えて，液状化によって剛性を失った地盤が煙突を支えることができず傾倒してしまうことを示した．つまり，地盤の上に建つ構造物の地震時挙動は，加速度の大きさのみで評価できるのではなく，構造物の固有周期と入射される地震動の卓越周期との関係性が極めて重要であることを意味する．また，地盤の不整形性および周辺構造物の影響評価を行ったところ，深部地層の傾斜や周辺構造物による引きずり込み沈下によって，上部構造物の地震時安定性が低下することを示した．

DOI： http://doi.org/10.2208/jscejam.72.I_409

An attempt on experience-based vibration engineering program building to perform a lecture vibrated freely Reviewed

Vol. 53 ( 1 ) page： 99-101 2017.1

A full formulation-based soil-water coupled finite deformation analysis on undrained compression tests on highly permeable soil specimen

Toyoda T., Noda T.

ICSMGE 2017 - 19th International Conference on Soil Mechanics and Geotechnical Engineering Vol. 2017-September page： 863 - 866 2017

Language：English Publishing type：Research paper (scientific journal) Publisher：ICSMGE 2017 - 19th International Conference on Soil Mechanics and Geotechnical Engineering

In the mechanics of saturated soil based on the theory of mixtures, the pore water pressure p and the displacements u and U of the solid and liquid phases, respectively, are assumed to be independent variables that are unknowns of the field when solving the equation of motion of each phase by coupling with the law of conservation of mass. This is called full formulation. In many analysis codes for saturated soil, this strict formulation is modified to reduce the number of equations by assuming that the acceleration of the liquid phase relative to the solid phase is much smaller than that of the solid phase (u-p formulation). As this assumption neglects the dynamic permeation of pore water, it has not been possible to apply u-p formulation to soils with very high permeability. This paper demonstrates that by utilizing the finite element method, the finite volume method, etc., it is possible to carry out deformation analysis of soils with very high permeability by solving the strict governing equations based on full formulation for finite deformation fields of soil-water coupled systems.

Scopus

名古屋港ポートアイランドの埋立地盤・基礎地盤の土質性状の把握と想定南海トラフ巨大地震に対する耐震性評価 Invited

酒井崇之，野田利弘，中野正樹

基礎工 Vol. 44 ( 11 ) page： 84-87 2016.11

Application of numerical analysis for long-term settlement prediction of an embankment on soft ground and its ex-post evaluation

Vol. 64 ( 10 ) page： 14-15 2016.10

Construction Experiment of Reinfoced Soil Wall Using Reinforcement Member Incorprating Both Friction Resistance and Bearing Resistance Reviewed

Muto, H., Kamiya, T., Naganuma, A., Kodaka, T., Ying, C.,Nakano, M. and Noda, T.

Vol. 11 ( 3 ) page： 201-214 2016.9

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

The reinforced earth wall have come into wide use in Japan after the Great Hanshin Earthquake in particular. Various types of reinforcing members are applied in that reinforced earth walls, e.g. metal strips, geosynthetics, steel bars with a bearing plate, and so on. Some of them have been developed in Japan. The authors have newly developed a reinforcing member incorporating both bearing resistance and friction resistance. In the present paper, a series of the small-scale pull-out test of the reinforcing members consisting of a steel bar with friction plate and bearing plate are performed to confirm the effectiveness of the reinforcement. From the test results, as to the cross-sectional shape of the friction plate, the friction plate of long shape in depth direction performed large pull-out resistance compared with the plate of short shape of the same sectional area. Enough resistance of the friction plate was demonstrated by setting it apart from a bearing plate in order to cut off the influence of the bearing plate. Furthermore, in the beginning of the pull-out, a ratio of contribution of the friction resistance to the bearing resistance was 60 to 70%. The contribution ratio of the friction resistance decreased to 40 to 50 % in a final stage of pull-out.

DOI： 10.3208/jgs.11.201

Seismic response analysis of centrifugal model test on embankment foundation systems

Nakai, K. and Noda, T.

Proc. of the 12th World Congress on Computational Mechanics page： [MS983-5] (151147) 2016.7

Analysis of the effect of groundwater level on the seismic behavior of an unsaturated embankment on clayey ground Reviewed International journal

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

Soil Dynamics and Earthquake Engineering Vol. 85 page： 217-230 2016.6

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

Numerous river levees on clayey soil grounds were damaged by the 2011 off the Pacific coast of Tohoku Earthquake. In order to investigate such damage, the behavior of an unsaturated embankment on clayey ground was simulated during its construction, during an earthquake and after the earthquake. The simulation was carried out using a soil-water-air coupled finite deformation analysis code, with attention being focused on the effect of groundwater level. The results indicated that if the groundwater level is high, a saturated area (settlement-induced saturation area) is formed at the base of the embankment due to penetrative settlement during/after construction. In addition, the mean skeleton stress is low compared with the low groundwater level. As a consequence, in the embankment on ground with the high groundwater level, the co-seismic deformation is greater and the mean skeleton stress decreases sharply, particularly in the settlement-induced saturation area during the earthquake. It was also shown that after the earthquake, the groundwater level rises because water flows toward the unsaturated embankment from the settlement-induced saturation area and/or the saturated clayey ground. If the groundwater level is high, in particular, a phreatic line is formed temporarily within the embankment.

DOI： 10.1016/j.soildyn.2016.02.008

Investigation of soil properties and estimation of upward wave in foundation ground of Urayasu area during the Great East Japan Earthquake using K-NET record motions Reviewed

KANEDA Kazuhiro, NAKAI Kentaro, NODA Toshihiro, ASAOKA Akira and SAWADA Yoshihiro

Vol. 16 ( 4 ) page： 4_155-4_166 2016.3

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

The widespread liquefaction disaster that occurred in the reclaimed land around Tokyo bay area during the Great East Japan Earthquake was alarming. Validating this disaster by simulation is needed to prevent any liquefaction that may occur during likely huge future earthquakes. To this end, accurate soil properties and appropriate input wave as well as the finite deformation analysis that simulates the reappearance of liquefaction should be comprehended. In this study, soil-water coupled analysis code GEOASIA with SYS Cam-clay model, which can reproduce the function of soil structure, was used. Firstly, elasto-plastic properties of Urayasu soils were identified from the results of boring survey and laboratory testing. Then, by means of transfer method, both NS and EW upward waves at the foundation ground were simultaneously estimated from K-NET recorded motions at Urayasu.

DOI： 10.5610/jaee.16.4_155

Effects of initial imperfection on the Riedel shear bands in surface ground due to strike-slip fault Reviewed

Vol. 71 ( 2 ) page： I_463-I_474 2015.12

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

A slip on the strike-slip fault causes flower structures and Riedel shear band within the overlying cover. This paper simulates the formation of these structures, employing the dynamic elasto-plastic finite defor-mation analysis code GEOASIA®.
The main conclusions are as follows: (1) A set of Riedel shear structures accompanies the plastic ex-pansion of the material, (2) A pattern of the initial material imperfections dominantly influence the for-mation process of Riedel shear structures and (3) Riedel shear bands don't appear in larger models, whose bottoms have more lightly overconsolidated by higher overburden pressure.

Evaluation of mechanical behavior of a large river levee during seepage and during/after earthquake based on soil-water-air coupled finite deformation analysis Reviewed

Vol. 71 ( 2 ) page： I_621-I_632 2015.12

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

In this study, seepage/seismic behavior of a large river levee on alternately layered ground of sandy and
clayey soil was evaluated by a soil-water-air coupled finite deformation analysis code. The main findings
are as follows: 1) Focusing on the river level, the analysis during seepage and during/after an earthquake
was performed. The higher the river level, the larger the deformation in a direction toward the landside. 2)
If the water permeability of the sandy soil layer is as high as 'gravel', 8 hours after the river level rose, ground heaving which will lead to piping occurred near the landside toe. This is because the permeability of covering clayey soil layer is low and much water was supplied from the river to the sandy soil layer. 3)In the case of high permeability in the sandy soil layer as 2), during an earthquake, even when the river level is low, pore water is able to migrate in the sandy soil layer underlying clayey soil layer with low permeability. This results in liquefaction of the top of the sandy soil layer though the permeability is as high as gravel.

Air coupled effects on triaxial shearing behavior of unsaturated silty specimens under constant confining pressure and various drained and exhausted conditions Reviewed

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

Soils and Foundations Vol. 55 ( 6 ) page： 1372–1387 2015.12

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

A simulation of triaxial shear tests on unsaturated silty specimens was performed under constant confining pressure and various drained and exhausted conditions starting from a single initial condition and passing through processes of suction variation and isotropic consolidation considering the triaxial test as an initial and boundary value problem. The simulation made use of a soil-water-air coupled finite deformation analysis code incorporating the SYS Cam-clay model as the constitutive equation of the soil skeleton and applying the average soil skeleton stress in the stress equation. The results showed that the coupling effect of the highly compressible air has a significant effect on the mechanical behavior. In addition, the results also explained other behaviors that would have been outside the capability of an analysis model that did not take account of factors other than air coupling such as suction. The authors wish to place special emphasis on the following findings:
(1) For simulation purposes, even using a soil water characteristic curve determined uniquely by the relationship between the degree of saturation and suction, it is still possible to calculate the increase in the degree of saturation for the drained and exhausted shear tests (under constant suction).
(2) A comparison of the experimental and calculated initial stiffnesses, volumetric strains, etc. showed that suction has an inhibiting effect on plastic deformation not only in drained and exhausted, but also in undrained and unexhausted conditions.
(3) For tests in which the volumetric restraint conditions of specimens were varied by controlling the air pressure under undrained conditions, results suggested that an introduction of gas leading to a rise in gas pressure within a highly structured ground may produce a risk of the ground displaying strain softening behavior. In the simulation, it was shown that this softening behavior can be represented in terms of structure decay as described by the SYS Cam-clay model.

Seismic Response Analysis of Ground/Geo-structures using Geo-Analysis Integration Code

Vol. 63 ( 10 ) page： 16-19 2015.10

Application of seismic response analysis under level 2 earthquake for an existing river embankment

Vol. 63 ( 10 ) page： 28-31 2015.10

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

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

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

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

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Papers - NODA, Toshihiro