担当区分：筆頭著者   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

A round-robin centrifuge model test for an identical saturated sloping deposit with various initial conditions was conducted in the framework of liquefaction experiments and analysis project (LEAP) with 10 international institutes. To pursue two main objectives: (1) the validation of the generalized scaling law (GSL); and, (2) the development of additional experimental data that fill the gaps in the previous LEAP, each institute was assigned two tests, identical in prototype scale: a model following the generalized scaling law and a model following conventional centrifuge scaling law. The test results show a significant match in the dynamic behavior of these models, which validates the applicability of the GSL under given conditions. However, in this study, a deviation is observed when the surface ground deformation becomes larger (i.e., 250 mm). The trend surface that correlates peak amplitude of input acceleration (PGAeff), the relative density of the ground (Dr_qc(2.0 m)), and surface lateral displacement (Ux) is updated and confirmed with new data sets.

DOI： 10.1016/j.soildyn.2022.107237

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掲載種別：研究論文（学術雑誌）   出版者・発行元：Informa UK Limited  

DOI： 10.1080/13632469.2020.1751346

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担当区分：筆頭著者   掲載種別：論文集(書籍)内論文  

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担当区分：筆頭著者  

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掲載種別：研究論文（学術雑誌）  

© 2020 Elsevier Ltd The Liquefaction Experiments and Analysis Project (LEAP) is a joint international project that pursues the verification, validation and uncertainty quantification of numerical liquefaction models. As part of this project, eight centrifuge models were developed at the facilities of Kyoto University, to simulate the dynamic behavior of a submerged, uniform-density, 20 m long, 4 m deep and 5° sloping deposit of Ottawa F-65 sand. The results are intended to compose part of a reliable database in the development of current and future V&V processes of liquefaction models. This paper presents the main characteristics of the model preparation and testing process, and an analysis of: (1) the validity of the “Generalized Scaling Law” for centrifuge modeling (2) the consistency and repeatability of the tests by means of the development of an additional repeatability-test, and numerical modelling, and (3) the importance of the viscosity of the fluid in liquefaction modelling.

DOI： 10.1016/j.soildyn.2020.106472

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記述言語：日本語   出版者・発行元：公益社団法人 地盤工学会  

<p>一般的な水道管布設工事で管を埋設する場合，掘削した発生土は廃棄処分され，埋戻しには砂系の購入土が使用されることが多い。ここで，発生土を埋戻し土として活用できれば，自然環境への負荷及び工事費用の低減が可能となる。国土交通省から通達された「発生土利用基準について」により，改良せず使用可能な発生土が定められているが，煩雑な室内土質試験が必要であり発生土の活用は広く普及していない。本研究では，原位置での発生土の簡易判別法（FK法）を全国各地の発生土に対して適用したうえで，発生土が一般の埋戻し土として利用可能かどうかを「水道管布設工事現場を再現した転圧実験」から得られる供試体の各種試験結果等をもとに評価した。その結果，FK法で合格とされた土は，購入土と比較し遜色ない締固め度及び強度が得られ，発生土の簡易判別法としてのFK法の適用性が示された。</p>

DOI： 10.3208/jgs.15.257

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.1016/j.soildyn.2022.107237

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掲載種別：研究論文（国際会議プロシーディングス）  

© 2019 Associazione Geotecnica Italiana, Rome, Italy. As part of the LEAP Project, three centrifuge tests were carried out in the facilities of DPRI at Kyoto University. The experiment aims to simulate the dynamic response of a uniform-density sloping deposit of clean sand, subjected to a ramped sinusoidal wave; this paper introduces specific details of the model preparation, testing procedures, and the achieved response. Additionally, a brief discussion related to the median values and variability of the relative density (Dr), and the peak ground acceleration (PGA) is presented, because these were identified as the “key parameters” for the estimation of the horizontal surface displacement due to lateral spreading (Ux). As an attempt of the sensitivity analysis, a series of Monte Carlo simulations were developed in order to analyze the sensitivity in the estimation of Ux under the variabil-ityofthekeyparameters.

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掲載種別：研究論文（国際会議プロシーディングス）  

© 2019 Associazione Geotecnica Italiana, Rome, Italy. This paper presents the applicability and application limits of predicting liquefaction damage for sheet pile structural model using the strain space multiple mechanism model based on the large deformation theory called “FLIP TULIP”. Specifically, the results of centrifuge model test conducted on the sheet pile structure model and the stress generated in the soil-structure interaction numerical model obtained using FLIP TULIP were compared and examined. As a result, combining the soil and structure with joint elements (Ks = 0), numerical simulations adequately reproduced experimental results of soil deformation and the bending moments of sheet pile. Therefore, it was confirmed that the large deformation analysis provides realistic results.

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掲載種別：研究論文（学術雑誌）  

© 2017 Elsevier Ltd The LEAP international collaboratory is introduced and its key objectives and main accomplishments during the planning phase of the US-LEAP (LEAP-2015) are presented. The main theme of LEAP-2015 was lateral spreading of sloping liquefiable soils. A summary of the results of the laboratory element tests performed on the selected soil (Ottawa F-65) is presented. The numerical simulations submitted by several predictors at different stages of the project are compared with the measured responses of sloping deposit specimens tested in a rigid box at six different centrifuge facilities around the world. The comparisons are presented for three rounds of simulations labeled here as types A, B, and C simulations. The type A simulations involved the response of the soil specimen to a prescribed base excitation with a maximum amplitude of 0.15g (Motion #2). Comparisons of the numerical simulations with the experimental results show that a sub-set of type A simulations were in reasonably good agreement with the responses measured in the reference centrifuge experiment. The predictors subsequently assessed the performance of their type A simulations by comparing them to the measured responses, made the necessary adjustments in their models, and conducted a type B simulation of the response of the same soil specimen subjected to an amplified base excitation with a maximum amplitude of 0.25g (Motion #4). In these type B simulations, the achieved base motions were used and the simulations showed an improved correlation with the experimental results. The predictors also conducted a type C simulation of the original test (Motion #2) using the base motions achieved on the six centrifuge facilities. The results showed very good agreement with the experimental results.

DOI： 10.1016/j.soildyn.2017.05.015

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掲載種別：研究論文（学術雑誌）  

© 2017 The Liquefaction Experiments and Analysis Projects (LEAP) is an international effort to produce a set of high quality test data and to then use it in a validation exercise of existing computational models and simulation procedures for soil liquefaction analysis. A validation effort (LEAP-GWU 2015) was undertaken using a benchmark centrifuge model of a sloping deposit tested in a rigid-wall container. This article presents and discusses the shear stress-strain responses and effective stress paths of the LEAP-GW 2015 centrifuge tests and numerical predictions (including an assessment of the effects of the rigid boundaries).

DOI： 10.1016/j.soildyn.2017.10.014

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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DOI： 10.2208/jscejseee.74.I_598

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記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

熊本地震では，水道施設にも多数の被害が生じたが，河川に囲まれた軟弱な粘土層と飽和砂層で構成された低地にある水道用井戸の水源地周辺においては，想定していなかった顕著な地盤変状に伴う水道施設の被害や，新耐震基準以降に建設された水道施設の建築物に基礎被害が多数確認された．筆者らは，浄水場や下水処理場および上下水道管路網の地震被害軽減対策を研究しており，これらの水道施設の被害と液状化を含む地盤の地震時挙動との関連性や対策に関する知見を得るために各種調査や検証解析を実施した．本報告では，これらの調査結果を報告するとともに，熊本市の水道事業において特に重要な井戸水源地施設の基礎杭及び井戸ケーシングを対象として，地震被害のメカニズムや要因を分析し，今後の耐震設計における留意点などを考察した．

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DOI： 10.4186/ej.2018.22.3.291

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier Ltd  

This paper presents a description of testing procedure and results of the LEAP-GWU-2015, and an investigation of the effect of the radial gravity field in centrifuge modelling. Dynamic responses of two models are compared. One had a planar surface with a 5° slope relative to the base of the container
the other had a curved surface to maintain a constant slope angle with respect to the radial g-field. For the centrifuge tests employed in this study, the slope and base excitation are in the tangential direction to spinning centrifuge. Results show that spikes in acceleration records due to cyclic mobility associated with lateral displacements appeared on both models. However, for the plane surface model, acceleration spikes in the negative (upslope) direction are more prominent and the residual downslope ground deformation was larger. Larger lateral displacement was observed in the plane model, while surface displacements in the curved model are smaller and uniform along the length of the model. For the plane model, the radial gravity acting near the slope top is almost constant and gradually increases towards the slope toe which causes a net increase in effective slope angle. Curving the model ground surface is recognized as leading to uniform lateral displacements along the length of the model surface.

DOI： 10.1016/j.soildyn.2018.05.005

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DOI： 10.1016/j.soildyn.2018.07.00

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DOI： 10.1080/13632469.2018.1469441

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DOI： 10.1016/j.soildyn.2017.05.018

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記述言語：日本語   出版者・発行元：関西大学先端科学技術推進機構  

CiNii Books

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記述言語：日本語   出版者・発行元：一般社団法人 地域安全学会  

<p>During a scenario earthquake with <i>M</i>_W9.0 along the Nankai Trough, strong ground motion is expected in the focal area, Wakayama Prefecture, Japan. In order to simulate the seismic damage of railway structures, it is necessary to estimate strong motions at the sites of interest with sufficient accuracy, taking into account local site effects. In this study, seismic waveforms at 54 sites for permanent railway station along JR Kinokuni Line were predicted based on the SMGA models considering the empirical site amplification and phase effects. The predicted seismic waveforms will be useful for rational safety assessment of a railway structure.</p>

DOI： 10.11314/jisss.31.339

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

&nbsp;Liquefaction was investigated after the 6.8 Mw earthquake on March 24, 2011 (Tarlay earthquake) in Chiang Rai Province, Northern Thailand. Several investigations including soil boring, SPT, and SASW tests were carried out and the results were used to perform one dimensional wave propagation analysis using finite element method. The maximum acceleration of 0.206 g recorded in Chiang Rai was used as the input motion. The input motion was applied at bottom of soil column to observe soil behavior under seismic loading. The result shows that liquefaction could occur at shallow depth (0 to 16.5 m), which is also followed by settlement (1.8 to 4 cm) due to compressibility of soil during earthquake. The analysis result indicates that there is no significant dissipated pore water pressure on liquefied layer. The longer duration of liquefaction is identified on layer (SP-SM), which have the low SPT values. Excess pore water pressure from bottom layer might also concentrate at this layer. The concentration of excess pore water pressure may trigger the duration of liquefaction up to 50 seconds. In addition, the excess pore water pressure ratio linked to impacted depth warns that the soils with excess pore water pressure in range of 0.9 to 1 are possible to get worse impact if a stronger earthquake attacks this area in the future.

DOI： 10.2208/jscejseee.73.I_135

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掲載種別：研究論文（国際会議プロシーディングス）  

© 2017 Taylor & Francis Group, London. In this study, a centrifuge model tests and effective stress analyses are performed on a steel frame building with pile-foundation subject to Tsunami such as those seriously damaged during the 2011 off the Pacific coast of Tohoku Earthquake (Magnitude 9.0). The centrifuge model tests at a scale of 1/200 in geometry are performed to simulate the overturning of a building subject to combined effects of soil liquefaction and Tsunami. With the effective stress analyses, this study demonstrates the importance of the combined effects of soil liquefaction at pile foundations in addition to the external force of Tsunami.

DOI： 10.1201/9781315161563-10

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Elsevier BV  

In this study, centrifuge model tests and effective stress analyses are performed on a tsunami-affected breakwater similar to those that were seriously damaged during the magnitude-9.0 East Japan Earthquake in 2011. The centrifuge model tests are performed at a scale of 1/200 to simulate the failure of the breakwater. This study is a significant improvement on a previous one [1] by the same authors. The centrifuge model tests now allow the seepage flow to be blocked as well as admitted, and the effective stress analyses are now performed based on the finite strain formulation in order to take large deformations into account instead of just the infinitesimal strain formulation that is applicable only to small displacements. Both the centrifuge model tests and the effective stress analyses demonstrate the important part played by the seepage of pore water in the failure of the rubble mound, in addition to the wave force of the tsunami action. In particular, it is shown that the breakwater damage of 2011 could have been prevented or at least mitigated by preventing seepage flow in the rubble mound.

DOI： 10.1016/j.soildyn.2016.09.009

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J-GLOBAL

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

This paper reports the results of a series of centrifuge tests examining dynamic responses of single and 3 x 3 grouped piles embedded in sand and supporting SDOF and 2DOF structures. A total of 7 model tests were conducted with the centrifugal acceleration of 40 g. Each model was subjected to 12 sinusoidal waves with constant acceleration amplitude and varying frequencies. The results of the tests indicate that pile-head motion is dominated by two sequential frequencies: a lower frequency (f(SSI)) where pile head motion is substantially maximized and a higher one (f(pSSI)) where the response is minimized with respect to free field surface motion. These results confirm recent published numerical results on single piles supporting SDOF structures and generalize their findings to grouped piles supporting SDOF and 2DOF structures. The results show also strong mobilized kinematic interaction effect generating significant pile bending when the ground is excited at its resonant frequency. On the other hand, structural vibrations tend to impose large bending moments as the excitation frequency approaches the natural frequency of the coupled soil-pile-structure system. Distribution of pile bending moments in the group is found to be a function of the pile position and the excitation frequency. In contrast to inner piles having the greatest kinematic bending moments, outer piles have a more pronounced inertial ones. (C) 2016 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.soildyn.2016.08.002

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記述言語：中国語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Academia Sinica  

Lateral spreading due to liquefaction of sandy soils is a significant cause of damage to the important engineering facilities and buildings in earthquakes. FLIP ROSE is a two-dimensional finite element analysis program for seismic liquefaction problems. A strain space multiple mechanism model (cocktail glass model) is implemented in the program for analysis of the granular material. A two dimensional finite element model is proposed to predict and analyze liquefaction-induced lateral spreading in gently sloping ground under the seismic loading. This numerical simulation model is verified using the excess pore water pressure, the lateral acceleration, the arias intensity and the lateral displacement time histories recorded in three sets of free-field lateral spreading centrifuge tests. The computed response shows good agreement with the centrifuge test measurements. The final lateral displacements in the gently sloping ground with the different gradients are predicted by this simulation model after sandy liquefaction. It shows that the gradient of gently sloping ground plays a more and more important role in the liquefaction-induced lateral spreading as the depth increases.

DOI： 10.16285/j.rsm.2016.08.039

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：公益社団法人 地盤工学会  

Demands for the testing of large prototypes in geotechnical engineering are increasing, while restrictions are recognized, such as costs and limited scale of testing facility. To resolve such demands and restrictions, Iai et al. (2005) proposed a scaling law by combining the scaling law for centrifuge testing with the one for 1-g dynamic-model testing. They call it the "generalized scaling law" in dynamic centrifuge modelling. The objective of the present study is to investigate and point out issues on the applicability of the scaling law through the technique of "new" modelling of models for dynamic behavior of pile foundations in both dry and saturated sand ground. Through comparison in the prototype scale, the applicability of the scaling law to bending moments was confirmed on the condition that centrifugal acceleration was more than 4.9 g for dry condition, and 14.4 g for saturated condition of 1/100 scale model.

DOI： 10.3208/jgssp.JPN-026

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

Under seismic excitation, a pile undergoes stresses stemming from both the vibration of the surrounding soil (kinematic interaction) and that of the superstructure (inertial interaction). The relative contributions of kinematic and inertial interaction on the magnitude of seismic forces induced in pile foundations are investigated by means of nonlinear two-dimensional (2D) finite element (FE) analyses. The interaction between the pile and the surrounding soil in three-dimensional (3D) type was idealized in the 2D analysis using soil-pile interaction springs with hysteretic nonlinear load displacement relationships. Parametric analyses are carried out, focusing on normalized seismic forces in the piles as affected by typical characteristics of structures and piles as well as ground nonlinearity. The results of the study provide a new interpretation of the interplay between pile kinematic and inertial seismic forces. The numerical results showed that for relatively short/stiff piles or where structure's natural frequency is lower than that of the ground, the kinematic interaction can be the prime contributor to the seismic forces in the pile provided that the excitation frequency is not close to the natural frequency of the coupled soil-pile-struc ture system, f(SSI). In a frequency band approaching f(SSI), the inertial interaction generally prevails imposing large bending moments at or near the pile head. The results showed also that maximum kinematic seismic force does not always occur at the fundamental frequency of the deposit. For certain relative soil-pile stiffness and excitation amplitudes, the largest peak of the lcinematic seismic forces in piles can be occurring at the second mode. (C) 2015 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.compgeo.2015.05.011

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記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

東日本大震災では東京湾岸埋立地や利根川下流域を中心に広域的な液状化が発生し，住宅や道路，上下水道施設等に甚大な被害を与えた．筆者らは，浄水場や下水処理場および上下水道管路網の地震被害軽減対策を研究しており，上下水道施設の被害と液状化の関連性や液状化対策に関する知見を得るために，液状化被害が顕著であった浦安市，千葉県，潮来市，鰐川浄水場の他，兵庫県南部地震で被災した尼崎市に対してヒアリング調査を実施した．本報告ではヒアリングの内容をもとに，上水道管路の被害の特徴について整理し，地盤の液状化と被害の関連性や対策について考察した．

DOI： 10.2208/jscejseee.71.I_983

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記述言語：日本語   出版者・発行元：日本応用地質学会  

CiNii Books

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記述言語：日本語   出版者・発行元：日本自然災害学会  

CiNii Books

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記述言語：英語   出版者・発行元：公益社団法人 地盤工学会  

Large-scale liquefaction was caused by the 2011 off the Pacific coast of Tohoku, Japan, earthquake and many pipes in the liquefied ground suffered serious damages. One of the issues pointed out after the earthquake is the dynamic behavior and the mechanism of pipes near a structure in the liquefied ground. This study focuses on evaluating the dynamic behavior through centrifuge model test. Test results show that the uplift of pipes in the liquefied ground occurred during an earthquake and liquefaction happens at that time. After an earthquake, pipes start to sink with increasing effective stress. The characteristic of damage mechanism depends on the depth of pipes and the state of ground (in liquefiable layer, at ground water level, or in the unsaturated layer). The data also shows that the direction of force interacting pipes during liquefaction was only bending direction. So we should reconsider the design criteria for pipes which is widely used in Japan applying to axial force.

DOI： 10.3208/jgssp.v03.j02

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

Over the past twenty years after the VELACS project, with major advancement of computer simulation technologies, research works on numerical constitutive modelling of liquefiable sand have been conducted intensively. Contribution of the VELACS project on the development of numerical modeling in this field has never been underrated. However, with the development of new and innovative models, we believe that now is the time to revisit the project and help define direction of research for possibly another twenty years&#039;. As a pilot project for the future international collaborations to examine the capabilities of existing numerical techniques for liquefaction analysis through laboratory experiments and centrifuge tests, a Class A prediction is conducted by numerical modelers of four institutes for a series of centrifuge experiments of flat and inclined saturated sand deposits.A brief description of the experiments, results of the numerical predictions, and general remarks for the next step are presented in this paper. © 2015 Taylor &amp; Francis Group, London.

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その他リンク： http://orcid.org/0000-0002-1543-1626

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

When designing buried structures using a performance-based framework, it is important to estimate their uplift displacement. A simplified method is proposed for predicting the uplift displacement of a hollow cylinder structure buried in shallow backfill based on the equilibrium of vertical forces acting on the structure during earthquakes. However, this method only provides the maximum value, which frequently is overestimated in practical applications. To offset this limitation, first, the uplift behavior of buried hollow cylinder structures subjected to strong earthquake motions was simulated. Then, two-dimensional effective stress analyses based on the multiple shear mechanism for soil were conducted, and the results were compared with the centrifuge test data. The soil parameters were evaluated based on laboratory test results. The seismic response data from 20 g centrifuge tests were analyzed, and the results were generally consistent with the results of centrifuge model tests. In particular, the effective stress model showed a reasonable ability to reproduce the varying degrees of uplift displacement depending on the geotechnical conditions of trench soils adjacent to the hollow cylinder structures buried in shallow ground. (C) 2014 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.soildyn.2014.05.006

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記述言語：日本語   出版者・発行元：地盤工学会  

CiNii Books

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その他リンク： http://dl.ndl.go.jp/info:ndljp/pid/10422448

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCI LTD  

The influence of vertical loads on the lateral response of group piles installed in sandy soil and connected together by a concrete cap is studied through finite elements analyses. The analyses focus on the five piles in the middle row of 3 x 5 pile groups. The vertical load is applied by enforcing a vertical displacement equivalent to 2% of the pile diameter through the pile cap prior to the application of the lateral loads. The results have shown that the lateral resistance of the leading pile (pile 1) does not appear to vary considerably with the vertical load. However, the vertical load leads to 23%, 36%, 64%, and 82% increase in the lateral resistance of piles 2-5, respectively. The increase in the lateral pressures in the sand deposit is the major driving factor to contribute the change in the lateral resistance of piles, depending on the position of the pile in the group. The distribution of lateral loads among piles in the group tends to be more uniform when vertical loads were considered leading to a more economical pile foundation design. (C) 2013 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.compgeo.2013.09.022

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記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

粘性土地盤においては，不均質な地盤構成等に起因して圧密沈下量が一様にならない不同沈下が発生することがある．このような不同沈下等によって埋立土層の一部が大きく沈下した場合，上層の埋立土の状態は一様とならず，地震時の液状化の発生も一様とならない可能性がある．本研究では，遠心載荷装置を用いた実験を実施し，埋立土層底面に沈下が発生した場合の地盤内応力の変化および地震時の液状化の様相を検討した．その結果，沈下部直上で地盤内応力が減少し，地震前の地盤内応力が不均一となることを確認し，この不均一の程度はN値に換算してほぼ±50%と算定された．

DOI： 10.2208/jscejseee.70.I_751

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記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

津波防護施設として構築されている傾斜式護岸の耐震性不足による広域的な沿岸防災機能の脆弱性が指摘されている．効果的な耐震対策を推進するためには，性能とコストの両立を目指した最適化，想定外の地震動に対しても壊滅的被害を防止する粘り強い対策の選定が必要となる．本研究では遠心模型実験を行い溶液型薬液改良による対策に関する検討を行った．その結果，護岸直下から法面にかけては液状化に伴うせん断変形が卓越してそれら領域のみの改良であっても効果が高まり最適化が可能であることが確認できた．また，同対策は粘り強い対策であり，その要因は粘着力の効果で繰返し載荷時のひずみの累積が低減すること，さらに不透水境界形成により間隙水の移動が抑制されて正のダイレイタンシーに対して有効応力が高まりせん断抵抗が高まるものと考察された．

DOI： 10.2208/jscejseee.70.I_44

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ELSEVIER SCIENCE BV  

The 2004 earthquake in Niigata-ken Chuetsu, Japan, caused widespread damage to sewer pipelines due to uplift behaviors caused by ground settlement after liquefaction. Sewer pipelines, which are important lifelines, suffer damage when sewerage systems cease to operate over a long period of time. Manholes ejected from the ground's surface can disrupt traffic. To study the failure mechanism after the earthquake, the Nagaoka city government conducted an open-cut survey of the damaged sewerage systems. The main features of the collected data included the locations of damaged sections and the inclination of the sewer pipes before and after the earthquake. In the present study, the cause of damage to the sewerage systems was investigated using the datasets and the standard penetration test (SPT) borehole logs. The relationship between the sewer pipeline damage and the geological settings in the affected area reveals that the groundwater depth and the geotechnical properties of the original subsoils acted as the key parameters influencing the manhole uplift behavior. Also, the uplift mechanism was investigated through centrifuge modeling tests, and these findings agree well with the test results obtained in this study. (C) 2013 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.enggeo.2013.07.011

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

The strain space multiple mechanism model idealizes the behavior of granular materials based on a multitude of virtual simple shear mechanisms oriented in arbitrary directions. Within this modeling framework, the virtual simple shear stress is defined as a quantity that depends on the contact distribution function as well as the normal and tangential components of inter-particle contact forces, which evolve independently during the loading process. In other terms, the virtual simple shear stress is an intermediate quantity in the upscaling process from the microscopic level (characterized by the contact distribution and inter-particle contact forces). The stress space fabric (i.e. the orientation distribution of the virtual simple shear stress) produces macroscopic stress through the tensorial average. Thus, the stress space fabric characterizes the fundamental and higher modes of anisotropy induced in granular materials. Comparing an induced fabric associated with the biaxial shear of plane granular assemblies obtained via a simulation using Discrete Element Method to the strain space multiple mechanism model suggests that the strain space multiple mechanism model has the capability to capture the essential features in the evolution of an induced fabric in granular materials. Copyright (c) 2012 John Wiley & Sons, Ltd.

DOI： 10.1002/nag.2087

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掲載種別：研究論文（学術雑誌）  

This paper presents the finite strain formulation of a strain space multiple mechanism model for granular materials. Because the strain space multiple mechanism model has an appropriate micromechanical background in which the branch and complementary vectors are defined in the material (or referential) coordinate, the finite strain formulation is carried out by following the change in these vectors, in direction and magnitude, associated with deformation in the material. By applying the methodology for compressible materials established in the finite strain continuum mechanics, decoupled formulation that decomposes the kinematic mechanisms into volumetric and isochoric components is adopted for the strain space multiple mechanism model. Lagrangian (material) description of integrated form is given by a relation between the second Piola-Kirchhoff effective stress tensor and the Green-Lagrange strain tensor; Eulerian (spatial) description by a relation between the Cauchy effective stress tensor and the Euler-Almansi strain tensor. In particular, the volumetric strain is defined as a logarithm of Jacobian determinant. Lagrangian (material) description of incremental form is derived through the material time derivative of the integrated form. The counterpart in the spatial description is derived through the Lie time derivative, given as a relation between the Oldroyd stress rate of Kirchhoff stress and the rate of deformation tensor (sometimes called stretching in the literatures). An example is shown to discuss the applicability of the finite strain formulation. © 2012 John Wiley & Sons, Ltd.

DOI： 10.1002/nag.2084

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記述言語：日本語   出版者・発行元：京都大学防災研究所技術室  

京都大学防災研究所の遠心力載荷装置は2年前に更新を行った。更新によりアームの剛性を強化し, 振動台駆動時に加振周波数50 Hz付近でアームが共振する問題を解消した。しかし, 更新後の装置について, 実験者からプラットフォームの剛性不足, 新規に導入したプラットフォーム固定方式の欠陥, 振動台から上下動が発生しているとの指摘があった。これらの問題を改善するために, 昨年再度装置の改修を行った。改修によりプラットフォームを再度更新し, 固定方式についても改造を行った。本調査では, 更新したプラットフォームおよび振動台やアームに加速度計を設置し, 振動台の加振試験を行い, 振動特性を調査した。その結果, プラットフォームの剛性不足が改善したことを確認した。また, 振動台で発生していた上下動は, プラットフォームの固定, DITHERと呼ばれる振動台の制御信号, 振動台の機械的構造が主な原因であることがわかった。

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：WILEY-BLACKWELL  

The strain space multiple mechanism model idealizes the behavior of granular materials on the basis of a multitude of virtual simple shear mechanisms oriented in arbitrary directions. Within this modeling framework, the virtual simple shear stress is defined as a quantity dependent on the contact distribution function as well as the normal and tangential components of interparticle contact forces, which evolve independently during the loading process. In other terms, the virtual simple shear stress is an intermediate quantity in the upscaling process from the microscopic level (characterized by contact distribution and interparticle contact forces) to the macroscopic stress. The stress space fabric produces macroscopic stress through the tensorial average. Thus, the stress space fabric characterizes the fundamental and higher modes of anisotropy induced in granular materials. Herein, the induced fabric is associated with monotonic and cyclic loadings, loading with the rotation of the principal stress, and general loading. Upon loading with the rotation of the principal stress axis, some of the virtual simple shear mechanisms undergo loading whereas others undergo unloading. This process of fabric evolution is the primary cause of noncoaxiality between the axes of principal stresses and strains. Although cyclic behavior and behavior under the rotation of the principal stress axis seem to originate from two distinct mechanisms, the strain space multiple mechanism model demonstrates that these behaviors are closely related through the hysteretic damping factor. Copyright (C) 2011 John Wiley & Sons, Ltd.

DOI： 10.1002/nag.1091

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記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

地盤・構造物系の地震時被害推定においては，地盤や構造部材を適切にモデル化し，信頼性のある解析手法を用いる必要がある．本研究では，大変形理論に基づき拡張されたひずみ空間多重せん断モデルを用い，ケーソン式混成防波堤を対象に地震応答解析を実施した．その結果，従来の微小変形解析ではケーソン天端の沈下量などをやや過大評価しているのに対し，大変形解析では実際の被災程度に合致する値が得られた．このことより，材料非線形性に加えて幾何学的非線形性を適切に考慮することで，より精度の高い地盤・構造物系の地震時被害推定が可能になるといえる．また，液状化対象層の内部摩擦角にばらつきを与えて地震応答解析を実施した結果，大変形解析では微小変形解析と比較して，ケーソン天端の沈下量のばらつきが低減されることがわかった．

DOI： 10.2208/jscejseee.69.I_385

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Because low-compacted trench backfill around a manhole is normally liquefiable, the manhole could suffer uplift damage associated with soil liquefaction during a strong earthquake. In this study, 22 dynamic centrifuge models were tested to investigate the response of a buried manhole subjected to a dynamic load. The models were tested under 20g, and a substitute pore fluid was used to avoid the scaling law conflict between the dynamic and diffusion processes. It was found that excess pore water pressure is one of the contributing factors to the magnitude of the manhole uplift. Using this result, new mitigation methods against the uplift in liquefied ground were developed. Their effectiveness was also examined through the tests. A model manhole mitigated with the proposed methods was tested alongside regular model manhole. From the test results, the magnitude of manhole uplifts with the mitigation methods decreased as buildup of the excess pore water pressure was restrained in high-compacted backfill or excess pore water was dissipated into the manhole during strong shaking. © 2013 American Society of Civil Engineers.

DOI： 10.1061/(ASCE)GT.1943-5606.0000769

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記述言語：日本語   出版者・発行元：京都大学防災研究所技術室  

The geotechnical centrifuge at the Disaster Prevention Research Institute, Kyoto University was renewed two years ago. Consequently, the rigidity of the main frame of the device had improved. However, some problems emerged by subsequent use. The 1st problem was that the rigidity of the platform part of the device was low. The 2nd one was that the fixed system of the platform part adopted did not function. The 3rd one was that vibration of the up-and-down direction in the shaking table occurs when dynamic centrifuge tests were. In order to solve those problems, the platform part was renewed last year to what has high rigidity, and the fixed system was also changed. In the present study, we investigated the dynamic characteristics of the shaking table and the platform part by measuring the vibration when dynamic centrifuge tests were. As a result, it was found that the causes of vibration of the up-and-down direction were the structure of the shaking table and the control signal called "DITHER". Additionally, it compared with the result when not fixing a platform part. Based on the comparison results, it is suggested that it be used without fixing the platform part.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ASCE-AMER SOC CIVIL ENGINEERS  

A simple method to predict the uplift displacement of a manhole and trench-backfill settlement due to liquefaction is proposed. The conventional equilibrium of vertical forces acting on a manhole is solely a function of such forces acting and is incapable of predicting the uplift displacement. In this paper, the proposed method adds variables including the uplift displacement, Delta f, and settlements of backfill, Delta s, under the condition that the volume of an uplifted portion of a manhole is equal to a settled volume of a trench-backfill. To date, the method is verified through comparison with the results of 1-G and centrifuge model tests. A new safety factor, which takes into account the amount of manhole uplift and backfill settlement, is also derived. DOI: 10.1061/(ASCE)GT.1943-5606.0000615. (C) 2012 American Society of Civil Engineers.

DOI： 10.1061/(ASCE)GT.1943-5606.0000615

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記述言語：日本語   出版者・発行元：社団法人地盤工学会  

本文データは地盤工学会の許諾に基づき登録したものである平成23年（2011年）3月11日に発生した東北地方太平洋沖地震による宮城県北部地域の地盤被害状況を把握するため，地盤工学会東北支部・関西支部合同調査団を組織し，2011年4月5日～10日，29～30日にかけて調査を実施した. 本論文では，その後の聞き取り調査なども踏まえ，河川堤防，海岸堤防，港湾施設，道路・鉄道の盛土・切土斜面，液状化や地盤沈降などの被害に関する調査結果を報告する. 調査結果の一部は既に地盤工学会誌に速報として報告されているが，本論文ではそこで報告された被害事例も含めて被害対象ごとに整理して述べる.

DOI： 10.3208/jgs.7.37

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記述言語：日本語   出版者・発行元：社団法人地盤工学会  

本文データは学協会の許諾に基づきCiNiiから複製したものである

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その他リンク： http://hdl.handle.net/2433/171985

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ICE PUBLISHING  

To verify and find issues on the generalised scaling law for dynamic centrifuge tests, a series of centrifuge model tests are conducted under the scheme of the modelling of models technique. In a series of dynamic tests on a flat, saturated sand layer, four different centrifugal accelerations from 5 g to 70 g are applied to the scaled models for which the prototype is uniquely given. With the scaling law, the prototype is scaled down to 1/100. The models are exposed to sinusoidal input accelerations with 0.65 Hz and amplitudes of 2.1 m/s(2) and 3.1 m/s(2) in prototype scale. For response during shaking, nearly identical accelerations and excess pore-water pressure build-ups are recorded for all the cases in the prototype scale. Discrepancies are found on surface settlements and duration time for dissipation of excess pore-water pressure. The major cause of the discrepancy may be the small value of the shear modulus induced by the low confining stress in model ground under low centrifugal acceleration.

DOI： 10.1680/ijpmg.2011.11.4.138

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記述言語：英語   出版者・発行元：公益社団法人 土木学会  

The non-linear response of coupled soil-pile-structure systems to seismic loading is parametrically studied in the frequency domain using two-dimensional (2D) finite elements (FE). The soil-pile interaction in three dimensions (3D) is idealized in the 2D type using soil-pile interaction springs with non-linear hysteretic load displacement relationships. The system under investigation comprises of a single degree of freedom structure supported by an end-bearing single pile founded in a homogenous sand layer over rigid rock. Comparisons with established results from the literature suggest that the adopted FE model reasonably captures the essential features of the seismic response of the coupled soil-pile-structure system. Numerical results demonstrate the strong influence on the effective natural period of the foundation properties. The effect of non-linear soil behavior and soil profile as well as the frequency content of excitation on both kinematic and inertial interactions is illustrated. The relative contributions of kinematic and inertial interaction to the development of dynamic pile bending are clarified.

DOI： 10.2208/jscejam.67.I_471

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記述言語：日本語   出版者・発行元：京都大学防災研究所  

京都大学防災研究所の遠心力載荷装置は2年前に更新を行った。更新によりアームの剛性を強化し，振動台駆動時に加振周波数50Hz付近でアームが共振する問題を解消した。しかし，更新後の装置について，実験者からプラットフォームの剛性不足，新規に導入したプラットフォーム固定方式の欠陥，振動台から上下動が発生しているとの指摘があった。これらの問題を改善するために，昨年再度装置の改修を行った。改修によりプラットフォームを再度更新し，固定方式についても改造を行った。本調査では，更新したプラットフォームおよび振動台やアームに加速度計を設置し，振動台の加振試験を行い，振動特性を調査した。その結果，プラットフォームの剛性不足が改善したことを確認した。また，振動台で発生していた上下動は，プラットフォームの固定，DITHERと呼ばれる振動台の制御信号，振動台の機械的構造が主な原因であることがわかった。

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その他リンク： http://hdl.handle.net/2433/161853

記述言語：英語   出版者・発行元：京都大学防災研究所  

遠心場において拡張型相似則の検証を行う．着目したのは乾燥砂地盤の振動による沈下量である．同相似則の適用性の確認は、測定された各物理量の実物スケール換算値が全実験ケースで一致することをもってなされる。模型地盤はフォンテーヌブロー砂による水平成層乾燥砂地盤(Dr=40%)であり，加速度計10台とレーザー式変位計1台および沈下計3台を設置した。実験は模型縮尺を1/100とし、25gと50gの遠心場における地盤の挙動を計測した．実験ケースは，全5ケースである。各ケースにおいて，正弦波加振を10回行った．また，加振前と10回の加振後に貫入抵抗の計測を行った．入力加速度については，Arias Intensityを計算し，プロトタイプスケールでほぼ一様な入力がなされていることを確認した．地表面の沈下量について，加振第1回目の実物換算値は全ケースで約900mmとなり，同相似則の適用性が確認できた．

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その他リンク： http://hdl.handle.net/2433/161854

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 地盤工学会  

The uplift behavior of sewage manholes due to liquefaction in a trench is investigated through a series of dynamic centrifuge model tests. The objectives of a series of tests are to study the mechanism of the uplift and to obtain relationships among uplift displacement and factors affecting the uplift. The factors considered in the experiments are the ground water levels, the magnitude of input accelerations, the duration time of shaking, the relative densities of trench backfill and the native ground, the material of native ground, the volume of a trench, the apparent unit weight of a manhole, and the contact conditions at the bottom of a manhole. Test results show that the primary cause of uplift is the reduction of the effective confining stress near the bottom of a manhole due to strong shaking. The magnitude of uplift is found to be strongly correlated with the ground water depth, the intensity of shaking, the shear deformation of the trench, and the contact conditions at the bottom of the manhole. These findings are believed to be useful for engineering practice in the mitigation of the manhole uplift.<br>

DOI： 10.3208/sandf.51.1091

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記述言語：英語   出版者・発行元：公益社団法人 土木学会  

This paper presents the results of a numerical investigation conducted to study the effect of vertical loads on lateral response of a free head and a capped pile group in sand. A coupled soil-pile system is idealized through 2D finite elements with soil models idealized by a hyperbolic type multiple shear mechanism. The analysis focuses on the five piles in the middle row of a 3x5 pile group spaced at 3.92-pile diameters. The interaction between a pile and the surrounding soil in the 3D type is idealized in the 2D analysis using soil-pile interaction springs with a hysteretic non-linear load displacement relationship. The presence of vertical loads on free head piles increases the confining pressures in the sand deposit confined by the piles but the rate of increase in those outside the group is relatively small, resulting in the difference in a balance of lateral soil pressures acting at the back of and in front of individual piles. A vertical load applied to a group pile with a uniform vertical displacement of 0.1 pile diameter decreases the lateral resistance of the leading pile (pile 1) by 10 % and increases the lateral resistance of piles 3 and 5 by 14 and 35 %, respectively. The same trend with higher percentages of increase or decrease is observed in the capped pile group case.

DOI： 10.2208/jscejam.67.I_271

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記述言語：日本語   出版者・発行元：日本下水道協会  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CANADIAN SCIENCE PUBLISHING, NRC RESEARCH PRESS  

La performance d&apos;un groupe de pieux charge lateralement a permis d&apos;etudier l&apos;effet de la separation sol-pieu. Des essais a l&apos;echelle reelle, qui consistaient en une combinaison d&apos;un pieu unique et d&apos;un groupe de 3 5 pieux soumis a des charges laterales statiques et dynamiques, sont une occasion unique et permettent d&apos;effectuer une etude rigoureuse sans avoir recours a un retro-ajustement des parametres de facon arbitraire. Le systeme couple sol-pieu est represente par des elements finis en deux dimensions, et les modeles de sols sont representes par un mecanisme de cisaillement multiple de type hyperbolique. Des elements de ressorts non lineaires sont utilises pour representer l&apos;interaction sol-pieu par une relation de deplacement de charge non lineaire et hysteretique. Des elements de joints, avec un mecanisme de contact-separation, sont utilises pour representer l&apos;effet de separation a l&apos;interface sol-pieu. Le fait d&apos;ignorer la separation sol-pieu lors d&apos;essais statiques surestime la capacite ultime de support de charge laterale par 43% pour un pieu unique, et par 73% pour le dernier pieu dans un groupe de pieux rapproches. De plus, si l&apos;on neglige la separation sol-pieu lors d&apos;essais dynamiques, on surestime la courbe de chargement-deflection totale du groupe, autant pour la phase de chargement que la phase de dechargement.

DOI： 10.1139/T10-026

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SEISMOLOGICAL SOC AMER  

During the 2008 Iwate-Miyagi Nairiku, Japan, earthquake (M(w) 6.9), an unprecedented vertical surface acceleration of nearly four times gravity, was measured at the KiK-net, IWTH25 station located 3 km southwest of the epicenter. The station is equipped with three-component accelerometers, installed at both the free surface and the bottom of a 260-m borehole. The waveform of the vertical acceleration shows a clearly asymmetric form with large amplitude in the upward direction. Aoi et al. (2008) reported and qualitatively explained the mechanism of this phenomenon by the analogy of bouncing a piece of matter on a trampoline; thus, they called it the trampoline effect. To study this recently discovered nonlinear behavior of the surface ground motion, numerical analysis with a two-dimensional finite-element method has been conducted with parameters derived from the borehole data at the station. The analysis successfully simulates the asymmetric vertical motion. Results indicate that the asymmetric motion may be characterized by the existence of a lower bound of negative acceleration, which in most cases corresponds to the acceleration of gravity and high positive pulses caused by the compression stress of the disturbed surface ground material.

DOI： 10.1785/0120090301

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記述言語：英語   出版者・発行元：wiley  

A granular material consists of an assemblage of particles with contacts newly formed or disappeared, changing the micromechanical structures during macroscopic deformation. These structures are idealized through a strain space multiple mechanism model as a twofold structure consisting of a multitude of virtual two-dimensional mechanisms, each of which consists of a multitude of virtual simple shear mechanisms of one-dimensional nature. In particular, a second-order fabric tensor describes direct macroscopic stress–strain relationship, and a fourth-order fabric tensor describes incremental relationship. In this framework of modeling, the mechanism of interlocking defined as the energy less component of macroscopic strain provides an appropriate bridge between micromechanical and macroscopic dilative component of dilatancy. Another bridge for contractive component of dilatancy is provided through an obvious hypothesis on micromechanical counterparts being associated with virtual simple shear strain. It is also postulated that the dilatancy along the stress path beyond a line slightly above the phase transformation line is only due to the mechanism of interlocking and increment in dilatancy due to this interlocking eventually vanishing for a large shear strain. These classic postulates form the basis for formulating the dilatancy in the strain space multiple mechanism model. The performance of the proposed model is demonstrated through simulation of undrained behavior of sand under monotonic and cyclic loading.

DOI： 10.1002/nag.899

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記述言語：英語   出版者・発行元：京都大学防災研究所  

"Modeling of models"の手法を用い, 動的遠心模型実験に用いられる拡張型相似則(Iai, et al. 2005)の適用性を検討する。実物の100分の1の飽和砂質水平成層地盤を対象に, 遠心加速度を5gから70gに変化させ実験を行う。模型地盤に対し, プロトタイプスケールで最大入力加速度振幅2.5m/s2と3.1m/s2, 振動数0.65Hzの正弦波を与えた。いずれの実験ケースにおいても, 振動中の応答加速度, 水圧の挙動については, プロトタイプ換算値でほぼ一致した。しかし, 振動後の過剰間隙水圧の消散過程において, 10g以下の低い遠心加速度を用いた場合に, 50g以上の高い遠心場の場合と比較して, 消散時間が4倍以上長くなる現象が見られた。低い遠心場では, 有効拘束圧が小さいため地盤の弾性係数が小さく, 圧密理論から予測されるように, 圧密時間(=水圧消散時間)が長くなるものと推察される。

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記述言語：日本語   出版者・発行元：京都大学防災研究所  

平成23年(2011年)3月11日午後2時46分に発生した東北地方太平洋沖地震を受け，4月5日から8日にかけて，宮城県北部の主に港湾，漁港施設及び河川堤防の被災状況を，5月9日と10日に茨城県の港湾施設および霞ヶ浦周辺の宅地の液状化被害状況を調査したので報告する。

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その他リンク： http://hdl.handle.net/2433/149602

記述言語：英語   出版者・発行元：京都大学防災研究所  

乾燥砂地盤中の単杭の地震時挙動について調べるため, 遠心模型実験を行う。模型短杭は先端支持杭であり, 1または2自由度の上部工を杭頭に取り付 ける。動的挙動を調べるため, 40ｇの遠心場で, 一定の振幅約1.5m/s2, 1Hzから12Hzの振動数で正弦波加振する。実験結果に基づい て, 慣性の相互作用と幾何的相互作用, および自由度の違いが全体系の応答に与える影響について考察したところ, 入力加速度の振動数が相互作用に与 える影響について興味深い結果が得られたので報告する。

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その他リンク： http://hdl.handle.net/2433/151066

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記述言語：日本語   出版者・発行元：京都大学防災研究所  

ひずみ空間多重せん断モデルは, 任意方向の仮想単純せん断機構の重ね合わせの機構により粒状体の挙動を表現する。この機構は, 粒状体の誘導異方性を反映する内部構造(微視的構造)を表現するもので, 2階のファブリックテンソルで表現され, このテンソルにより巨視的ひずみが巨視的応力に関連づけられる。この枠組みでは, ひずみ空間ファブリックは, 巨視的ひずみ場の個々の仮想単純せん断機構への投影として定義され, 粒子間の相対変位の方向分布を表す。ひずみ空間ファブリックは, 2次元では四つ葉のクローバー型をしており, 履歴型双曲線関数を通じて応力空間ファブリックに変換される。応力空間ファブリックは, 接点間の接点応力による微視的な応力の方向分布を表し, そのテンソル平均により, 粒状体の巨視的な応力が与えられる。個別要素シミュレーションによって得られた接点力の方向分布を示すファブリックは, ひずみ空間多重せん断モデルによる結果と整合的であり, 同モデルは粒状体の誘導異方性を的確に表現できることが示された。

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その他リンク： http://hdl.handle.net/2433/151068

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：SEISMOLOGICAL SOC AMER  

In this article, data were collected from the Chiba dense array, which consists of 44 accelerometers with interstation spacing in the range of 5-300 m that are employed to estimate the torsional ground motion. The geodetic method was used to estimate torsional motions from the translational records in the Chiba dense array. The translational and computed torsional motions were then applied to the building models with different structural characteristics to evaluate the effectiveness of the accidental eccentricity levels proposed in various design codes. The results of analysis suggest that the 5% accidental eccentricity is on the safe side for most periods of interest in engineering practice. However, in the case of stiff structures (with periods shorter than 0.3 sec), an increase of up to four times in building displacement is observed by including the torsional excitation. Furthermore, we found that the accidental eccentricity coefficient increased up to 0.6 at periods shorter than 0.3 sec, which is 12 times larger than what is proposed by the codes.

DOI： 10.1785/0120080196

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記述言語：英語   出版者・発行元：京都大学防災研究所  

40G場の遠心模型実験により，均一で密な砂地盤で下端支持杭を持つ2自由度構造物の動的応答について調べる。上部工の慣性力が杭基礎に与える影響を考察するため上部工の有無，入力正弦波の振幅と振動数を変化させて実験を行う。また，実験結果を2次元非線形動的有限要素解析結果と比較する。ただし，本質的に3次元の問題である杭?地盤の動的相互作用は，応力履歴を考慮できる地盤?杭相互作用ばねを導入し2次元でモデル化するものとする。加速度および変位時刻歴については実験と解析とで良い一致を示したが，曲げモーメントについては今後の検討が必要である。

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その他リンク： http://hdl.handle.net/2433/129397

記述言語：日本語   出版者・発行元：社団法人地盤工学会  

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その他リンク： http://dl.ndl.go.jp/info:ndljp/pid/10419628

記述言語：日本語   出版者・発行元：地盤工学会  

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記述言語：日本語   出版者・発行元：日本下水道協会  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

Dynamic behavior of a pile group is simulated by a two-dimensional finite element analysis. Results of the full-scale lateral-load tests of a 3 × 5 pile group conducted in the Salt Lake City International Airport site are compared with the simulation. The soil profile at the test site generally consisted of cohesive sandy silt and silty sand. Closed-end steel pipe piles were driven to a depth of 11.6 m. Pile head was rotation free. Dynamic lateral loads were applied to pile head with the statnamic device. To conduct numerical analysis, model parameters for soils are taken from the geotechnical investigation data at the test site. Response of five piles in the middle of the 3 × 5 pile group are simulated. Measured dynamic loads are applied at the pile head. Overall load-deflection behavior of the pile group agrees well with the measured ones. Some discrepancies are found on the bending moment profile. In the full-scale dynamic tests, peak moments for larger target deflections occurred at the same depths for all piles, while in computation, the peak moment occurs with greater depths as target deflection increases. Numerical analysis overestimates the group effects in dynamic tests. This calls up further improvement of a numerical modeling. © 2008 ASCE.

DOI： 10.1061/40975(318)138

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記述言語：日本語   出版者・発行元：京都大学防災研究所  

大地震時のマンホールの浮上りは，埋戻し土の液状化に伴う過剰間隙水圧の上昇によりマンホール底面に作用する上向きの力が，マンホールの自重，側面に作用する摩擦力および下水管接続部の抵抗力の合力を上回ったとき生じる．ただし，いったん浮上がった後沈まないためには，マンホール直下に埋戻し土が回り込まなければならない．したがって，浮上過程が非排水条件だと仮定すれば，マンホール直下に回り込んだ土の体積分，すなわち浮上したマンホール本体の体積分の沈下が埋戻し領域に発生すると考えてよい．ただし，間隙水圧消散に伴う埋戻し土自体の圧縮による沈下は相対的に無視しうるほど小さい(εv縲・%)とする．

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その他リンク： http://hdl.handle.net/2433/129311

記述言語：日本語   出版者・発行元：沿岸技術研究センター  

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記述言語：英語   出版者・発行元：京都大学防災研究所  

大地震時に液状化による埋設構造物の浮き上がりが生じた事例は数多く報告されている．2004年新潟県中越地震では，長岡市，小千谷市などで1, 400箇所以上のマンホールの浮き上がりが発生し，緊急車両の通行が阻害されるなど，市民生活に大きな影響を与えた．マンホールの浮上防止対策についても，埋戻し土の締固め，固化改良，砕石による埋戻し，間隙水圧をマンホール内に逃がす方法(小西ら，2008)などが考案されている．しかし，既存のマンホールに対する浮上防止対策については，有効かつ経済的な方法がいまだ模索されている．本研究では，遠心模型実験を用い，既存および新設のマンホールに対して間隙水圧をマンホール内に逃がす方法の有効性を評価した．その結果，浮き上り量は対策なしよりマンホール長さの12%まで低減された．

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その他リンク： http://hdl.handle.net/2433/129307

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

This paper describes an emerging methodology for seismic evaluation and design of port structures. The methodology is based on minimum life-cycle cost principle through probabilistic evaluation of performance. While conventional seismic design of port structures are based on a particular return period specified for design, the methodology based on life-cycle cost allows for consideration of ground motions with all (or varying) return periods and uncertainty in geotechnical conditions. The methodology based on life-cycle cost also allows the probability of failure being evaluated rather than prescribed by an authority. Since ordinary port structures are for commercial use, the method based on the life-cycle cost has potential advantages over conventional design. An example is presented. In particular, the simplified design charts that are based on a series of parametric studies of effective stress analyses have great benefit for implementing the proposed methodology in practice. Apart from the ordinary port structures, higher priority should be assigned for safety as a performance objective. This issue is especially relevant if port structures are essential parts of post-earthquake emergency strategies for recovery and restoration of urban areas. The paper also discusses the importance of this issue and the future direction of study. © 2008 ASCE.

DOI： 10.1061/40975(318)198

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記述言語：日本語   出版者・発行元：土木学会  

Uplifting of sewage manholes is one of the typical and striking damage pattern observed in the area being hit by large earthquakes. A simplified method to estimate the maximum uplift displacement of a manhole and settlements of backfill soil under liquefaction is derived based on the mechanism of uplift of a manhole under undrained condition of backfill soil. The method is capable of evaluating effectiveness of countermeasures against uplift by considering excess pore water pressure ratio and/or unit weight of backfill soil. In the present study, the applicability for the case without countermeasures is investigated through comparison with experimental results. Results show that measured uplift displacements and settlements are within the range predicted by the proposed method.

DOI： 10.2208/journalam.11.587

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記述言語：日本語   出版者・発行元：土質工学会  

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記述言語：日本語   出版者・発行元：日本自然災害学会  

A large earthquake occurred (Mj 6.8, D=17km) at 10 : 13 AM on July 16, 2007 in Chuetsu region, Niigata, Japan. The epicenter was located offshore of Kariwa village and Kashiwazaki city. Preliminary results of the source inversions indicate a reverse fault with the NE-SW (strike : 34, Dip : 51, Rake : 74 degrees). The instrumental JMA seismic intensity was 6+ (IX in MMI) in Kariwa village, Kashiwazaki city, Nagaoka city in Niigata prefecture, and lizuna-machi in Nagano prefecture. Eleven people were killed, more than 1, 813 were injured, and more than 10, 000 were evacuated (as of 7/23/07, Niigata Prefecture). The number of totally collapsed houses was 961 in Niigata. Major lifelines, gas, water, and electricity, have been damaged and suspended for more than a day. In Kariwa village, one of the world largest nuclear power plants (7 reactor's total 8, 200, 000kW) reportedly suffered damage due to unexpectedly large strong shaking.

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その他リンク： http://dl.ndl.go.jp/info:ndljp/pid/10752269

記述言語：日本語   出版者・発行元：日本自然災害学会  

A major earthquake (Mj 6.9, 37°13.2'N, 136°41.1'E, Depth 11km) occurred on March, 25, 2007, at 9:42PM (local time) near Noto Peninsula, Ishikawa Prefecture, Japan. The JMA seismic intensity of 6+ was recorded in Wajima city, Nanao city, and Anamizu-Machi. One person was killed, more than 318 were injured. The number of totally collapsed houses were nearly 600, and partially collapsed houses exceeded 1,200 (as of May 9, 2007). Strong shaking triggered damage of lifeline systems, road embankments, settlements and tilting of port facility, and slope failures of cliffs near the sea. This paper mainly reports characteristics of strong shaking, and damage on roads and port facility.

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その他リンク： http://hdl.handle.net/2433/171970

記述言語：日本語   出版者・発行元：社団法人地盤工学会  

本文データは地盤工学会の許諾に基づき登録したものである2003年12月26日イラン南東部に位置する人口約12万人の町バム市直下を震源域とする地震が発生した. 著者らは，地震発生約2ヵ月後に第1次調査として，バム市内とその周辺に観測点を設け微動観測，アンケート震度調査，建物倒壊率調査を行い，市内各所において震度や被害分布が異なることを明らかにした. 本報では，第2次調査として市内10点において行った弾性波探査結果を示すと共に，詳細なボーリングデータに基づいて実施した地震応答解析結果をもとに，表層のP波速度構造と建物倒壊率との関係について考察する.

DOI： 10.3208/jgs.2.51

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記述言語：英語   出版者・発行元：京都大学防災研究所  

本研究では，ソルトレーク国際空港で実施された実大群杭の静・動的載荷試験(Rollins et al. 1998, 2005)を対象として，地盤と群杭の相互作用を明らかにするため，2次元有限要素法を用い数値解析を行った。数値解析では動的な荷重だけを考慮した場合と動的載荷前の静的な荷重も考慮した場合の2種類の解析を行なった。数値解析より得られた荷重-変位関係と曲げモーメント曲線は実験結果と概ね一致した。また，準静的載荷が地盤の応力状態に及ぼす影響を明らかにするため，地盤のせん断応力-ひずみ関係を調べた。その結果，準静的な載荷過程を考慮することで解析の精度が向上することが確認された。

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その他リンク： http://hdl.handle.net/2433/73396

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPRINGER  

The paper discusses the emerging trends in seismic analysis and design of geotechnical structures. Soil consists of soil particles. The fundamental study on this aspect of soil has come to the stage where the results of the study can be readily incorporated as an essential part of seismic analysis of soil-structure systems. Geotechnical earthquake engineers and researchers are encouraged to look into this fundamental study. By expanding the concept of performance-based design, a paradigm shift can be achieved from construction-oriented to service-oriented approach. The service-oriented approach will open a new horizon for design and promote the holistic approach for providing better designed built-environment. Designing a large urban area against combined hazards, such as those caused by the Sumatra earthquake of 2004, poses a new challenge in seismic design. The approach that is most appropriate for a large urban area may be different from those used for the current practice design used for individual structure and should be newly developed. These emerging trends in seismic design have to be extensively studied and carefully applied in practice, especially for designing new and large geotechnical structures that have to meet the rapidly growing social and economic demands in Asia and those for redevelopment of urban areas around the world.

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記述言語：日本語   出版者・発行元：京都大学防災研究所  

本稿は，砂の繰返し載荷時の挙動モデルとして，新たなストレスダイレイタンシー関係を提案し，それをひずみ空間多重モデルに組込んだ形の定式化を提示する。提案するストレスダイレイタンシー関係は，ダイレイタンシーによる体積ひずみ成分が，仕事をしないせん断機構を表現する膨張的成分，および，累積せん断ひずみに比例する収縮的成分の和として与えられるという簡単な仮説に基づくものである。定式化とともに，このモデルを適用していられる砂の繰返し挙動の解析例を併せて示す。

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その他リンク： http://hdl.handle.net/2433/73402

記述言語：日本語   出版者・発行元：土質工学会  

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記述言語：英語   出版者・発行元：日本自然災害学会  

One of the largest earthquakes in our history occurred at 7:58AM (local time) on December 26 2004, off the west coast of Northern Sumatra Island, Indonesia (M_w 9.3). The earthquake triggered a huge tsunami along the coastlines of the Indian Ocean and caused a huge number of casualties. From March 1 to 6, 2005, reconnaissance was conducted in the region of Banda Aceh and Meulaboh, Indonesia, where strong shaking and tsunamis were observed. The primary objective of reconnaissance was to investigate and record damage mainly due to strong motions and to estimate the seismic intensity in the region. This paper reports on the damage to earth structures, waterfront structures, and roads washed away by tsunamis. Eyewitness evidence of liquefaction in Banda Aceh, about 250 km away from the epicenter, was likely caused by the strong shaking of M_w 9.3. In Kuala Bubon village located about 15 km north of Meulaboh, settlements of embankments attached to bridge abutments collapsed just after the earthquake and before the arrival of the tsunami, so villagers could not use motorcycles or bicycles to evacuate. Lessons must be learned from this devastating earthquake, and disaster mitigation improved.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：THOMAS TELFORD PUBLISHING  

The trend toward physical modelling of larger prototypes triggers a move towards expansion of the current capability of dynamic centrifuge tests. In this paper a method based on the concept of two-stage scaling is proposed that allows expanded use of the currently available facilities. In the first stage a prototype is scaled down into an intermediate virtual model based on the scaling relations in a 1g field with a scaling factor of mu (prototype/virtual model). In the second stage this model is scaled down into a physical model using the conventional scaling relations in the centrifugal field with a scaling factor of eta (virtual model/physical model). In this manner, a large scaling factor lambda = mu eta (prototype/physical model) can be broken down into the smaller scaling factors mu and eta, and thus the centrifuge model tests can be performed with the smaller scaling factor eta. In effect, the limits in the scaling factor for the currently available centrifuge facilities can be expanded by a factor of mu. Validation of the proposed method is provided by algebraic derivations based on the mechanics of model tests.

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記述言語：日本語   出版者・発行元：日本自然災害学会  

A major earthquake (M 6.8, 37.289 N, 138.870E, Depth 13km) occurred on October 23, 2004, at 5 : 56PM (local time) near Ojiya City, Niigata Prefecture, Japan. The JMA seismic intensity of 7 was recorded in Kawaguchi-machi for the first time after seismic intensity meters were installed. Aftershocks with the JMA seismic intensity scale of more than 5 minus had been measured for more than two weeks in the affected area. Forty people were killed, more than 4,500 were injured and more than 100,000 were evacuated for days. The number of totally collapsed houses exceeded 2,800. Strong shaking triggered more than 1,600 landslides, and some of them blocked up river channels in mountain area. The earthquake also caused major damage on civil structures. The Joetsu Shinkansen bullet train was derailed for the first time in its history of 40 years. The number of passengers was 151 and miraculously no one was injured.

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その他リンク： http://dl.ndl.go.jp/info:ndljp/pid/10751915

出版者・発行元：公益社団法人 土木学会  

現地調査は, スマトラ島沖大地震における強震動や地盤の液状化など, 津波以外の被害の実態を明らかにすることを目的とした. 調査地点は震源に近いスマトラ島バンダアチェ (Banda Aceh) およびムラボー (Meulaboh) である. 本報告では, 低平地における地盤に関する被害について報告する. 西海岸の河口デルタ周辺の村 (Kuala Bubon) での聞取り調査では, 地震直後に橋の取付け部の盛土が沈下し, 車やバイクでの避難が困難であったとの証言を得た. ムラボー市内では, 地震によるRC造建築物の倒壊がみられた. また沿岸部では津波によりほぼすべての住宅が流されていたが, 津波が到達しなかった内陸部の住宅は外見上ほぼ無被害であり, 沿岸部との対比は著しい.

DOI： 10.11532/proee2005.28.211

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出版者・発行元：公益社団法人 土木学会  

本研究では, 液状化地盤中に設置されたマンホールの浮上りについて遠心力載荷模型実験を通じた検討を行った. 遠心力載荷模型実験では, 地盤の密度および加振加速度を変化させ, 延べ6ケースの実験を実施した. 遠心模型実験により, マンホール模型浮上りの際に測定した過剰間隙水圧の値を基に, 現行設計基準類などに示されている簡易法による浮上り安全率を算定したところ, この安全率と浮上りの挙動とは矛盾する結果となり, 有限要素法などによる変形解析の重要性が改めて確認される結果となった.

DOI： 10.11532/proee2005.28.4

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記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

原地盤を飽和砂質地盤とする盛土に関して動的遠心模型実験, および有効応力解析プログラム (FLIP) による数値解析を実施した. 実験および解析においては, 原地盤の相対密度と入力波の加速度振幅に対する盛土および周辺地盤の変形形態と天端沈下量に着目した. 本研究により明らかになったことは以下のとおりである. (1) 入力加速度振幅にほぼ比例して, 盛土天端の沈下量が増大した. (2) 液状化地盤では自重による沈下が卓越し, 非液状化地盤では慣性力による変形が卓越する. (3) 飽和緩詰め地盤上の盛土沈下は, 原地盤要素が地震時のせん断力により鉛直方向に収縮, 水平方向に伸張することで生じる.

DOI： 10.11532/proee2005.28.37

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記述言語：日本語   出版者・発行元：京都大学防災研究所 / Disaster Prevention Research Institute Kyoto University  

杭―地盤相互作用に伴って生じる水平断面内での杭周辺地盤の変位・変形性状を詳細にとらえることを目的として模型実験を行った。実験した断面について，数値シミュレーションも実施し，模型実験から得られた結果の一般化を図った。数値シミュレーションにおいて用いた砂の力学モデルは，多重せん断機構に基づくモデルである。乾燥排水条件では，杭周辺の地盤変位ベクトルは杭前面では杭変位と同じ方向に，また，杭の側面では杭表面からの距離に応じて急速に変位が小さくなる傾向を示した。飽和非排水条件では，杭側面で渦状の変位形態が見られ，杭の前後では，それぞれ押出し，引込みの変位形態を示した。杭間の変位は，杭表面付近にひずみが集中する傾向が見られた。

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その他リンク： http://hdl.handle.net/2433/26627

記述言語：日本語   出版者・発行元：日本自然災害学会  

A destructive earthquake (M_W 6.6) occurred on December 26, 2003, at 7:56 GMT (5:26AM local time), near the city of Bam located southeastern part of Iran. There is the Bam fault just 2 km away from the city, which might be activated for the first time in several thousand years. The focal depth is estimated to be 8 to 10 km and the focal mechanism is reported to be dextral strike-slip with small vertical component. Strong motions were recorded in the city, about 14 km from the epicenter. The maximum peak ground acceleration was 1.0g in vertical, and 0.81g and 0.65g in horizontal components. The number of victims due to the earthquake exceeded 40,000 as of Feb. 26, 2004. A major cause of death could be crashed or hit by the debris while sleeping due to the collapse of housings. The earthquake also destroyed the historical mud brick complex, "Arg-e-Bam" which is more than 1,500 years old.

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その他リンク： http://hdl.handle.net/2297/23573

記述言語：英語   出版者・発行元：京都大学防災研究所 / Disaster Prevention Research Institute Kyoto University  

地下構造物の地震時挙動を，多重せん断機構に基づく砂の力学モデルに基づいて有効応力解析した。解析対象は，矩形断面の鉄筋コンクリート製（RC）が飽和および乾燥地盤の基盤に埋設されたもので，30g場での遠心実験に基づく。地震動加振の結果，RC構造物の側壁に作用する土圧は加振とともに増加し，RC構造物の側壁は降伏に至った。有効応力解析の結果は，RC構造物の地震時挙動をよく説明するものとなった。

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その他リンク： http://hdl.handle.net/2433/26518

記述言語：英語   出版者・発行元：京都大学防災研究所  

液状化による側方流動地盤中の杭基礎の挙動について、遠心模型実験および数値解析により考察した。模型実験は40分の1の縮尺で、用いた杭の配置は3x3の9本群杭、杭間隔は杭径の3倍である。杭の上下端は固定とした。杭基礎を配置した飽和地盤表面に傾斜30度を設け、地震波を入力し液状化による流動を発生させた。実験より、流動初期には杭頭の変位は地表面の変位に追随しているが、最終的な杭頭の変位は地表面変位よりも小さくなった。これは杭の剛性が高く杭間を土がすり抜けるためである。この実験結果より2次元有効応力解析法の妥当性について検討したところ、地盤ばねを適切に評価することで、すり抜けの効果を再現することができた。

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記述言語：英語   出版者・発行元：京都大学防災研究所  

低平地を中心として急速に周辺丘陵地へと拡大する都市域では，地震時液状化，宅地造成地盤崩壊，人工・自然斜面崩壊など，地盤災害の危険性が増している。本研究は，これらの地盤災害に対する都市域の脆弱性診断技術と危険度評価技術の高度化，地盤基礎構造物の性能向上技術の開発を目的とする。平成15年度のとりまとめとして，本論文では，廃棄物埋立護岸の環境脆弱性と性能向上，レーザースキャナー技術を用いた山地での表層崩壊発生危険度評価の提案，丘陵地斜面における地すべり災害の予測モデルの開発についてとりまとめた．

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その他リンク： http://hdl.handle.net/2433/129023

記述言語：日本語   出版者・発行元：京都大学防災研究所  

杭・地盤系の動的挙動の検討に当たり，遠心場で単杭，群杭の静的および振動水平載荷実験を行った。杭径30cm，杭長10mの鋼管杭を，静的載荷実験では縮尺1/20，振動載荷実験では1/40でモデル化した。杭頭は自由端，杭間隔は杭径の3倍で3x3に配置された群杭の乾燥砂及び飽和砂地盤中における水平力載荷時の挙動を調べた。乾燥砂を用いた振動実験では，静的実験とは異なり，最大荷重と最大変位の発生時刻が一致せずその履歴曲線は丸みを帯びたものになった。これは地盤と杭の挙動における位相差または地盤の非線形性によるものと推察される。一方，飽和砂を用いた実験では，液状化地盤中においても群杭効果と推察される結果が得られた。

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その他リンク： http://hdl.handle.net/2433/129251

出版者・発行元：公益社団法人 地盤工学会  

大地震時における群杭の挙動を明らかにする第1段階の検討として、遠心力場で単杭および群杭の静的水平載荷実験を行い、群杭効果に関する基礎的なデータを得た。この実験では、直径30cm、長さ10mの鋼管杭で杭間隔が杭径の3倍での群杭の原位置実大実験(米国ソールトレークシティーで実施)を対象に、縮尺1/20の模型を用いて、地表面変位が杭径の3割に達するまで載荷した。この結果、杭一本当たりの同一荷重に対して、群杭では単杭の1.6~1.7倍の変位が発生し、前方、中間、後方杭の順に最大曲げモーメントの発生位置が下がった。この結果と原位置実大実験結果とは、地盤条件の相違を考慮すれば、概ね整合性が見られる結果となった。

DOI： 10.11512/jiban.JGS38.0.1441.0

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記述言語：英語  

DOI： 10.1007/978-3-030-22818-7_1

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記述言語：日本語   出版者・発行元：電気評論社  

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記述言語：日本語   出版者・発行元：関西大学理工学会  

科学研究費助成事業基盤研究(B)(26282103,2014-2016)基盤研究(C)(25420502,2013-2015)遠心力載荷模型実験と数値解析に関する国際プロジェクト(LEAP)解説

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その他リンク： http://hdl.handle.net/10112/10712

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記述言語：日本語   出版者・発行元：京都大学防災研究所  

Kumamoto earthquake occurred in Kyushu Island, which is located at the south part of Japan, at 1:25 am on 16th April in 2016. The magnitude of the biggest earthquake was M7.3 and a lot of buildings and civil structures were damaged and collapsed due to the shaking generated by the sliding active fault overlain across the middle part of Kyushu Island. This paper shows the report of the site investigation performed at Mashiki-machi, Nishihara-mura and Minamiaso-mura in the term of 7th-8th in May.

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その他リンク： http://hdl.handle.net/2433/217308

記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）  

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記述言語：日本語   出版者・発行元：総合土木研究所  

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記述言語：日本語   出版者・発行元：社団法人地盤工学会  

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その他リンク： http://dl.ndl.go.jp/info:ndljp/pid/10420060

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記述言語：日本語   出版者・発行元：日本自然災害学会  

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その他リンク： http://hdl.handle.net/2433/171967

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記述言語：英語   出版者・発行元：CRC PRESS-TAYLOR & FRANCIS GROUP  

Iai et al. (2005) proposed a procedure of two-stage scaling for dynamic centrifuge tests to study the behavior of large geotechnical structures in the existing research facilities which allows high geometric scaling factors by superposition of scaling laws for centrifuge tests with those for 1 g shaking table tests. A series of tests on saturated sand deposits is conducted to verify the applicability of this approach. Seven different combinations of scaling factors and centrifugal accelerations up to 70 g are applied to scale the same prototype by 1/100. The models are exposed to sinusoidal input accelerations with 0.65 Hz and amplitudes of either 4.7 m/s(2) or 2.1 m/s(2) in prototype scale. The two-stage scaling approach is verified for the buildup of excess pore water pressure. During the dissipation of pore water pressures after shaking, limitations seem to arise concerning ground settlements and when low levels of centrifugal accelerations are applied.

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記述言語：英語  

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記述言語：英語   掲載種別：研究発表ペーパー・要旨（国際会議）  

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記述言語：英語   出版者・発行元：CRC PRESS-TAYLOR & FRANCIS GROUP  

Centrifuge model tests are conducted to investigate the mechanism of uplifting of buried underground structures, in particular in this study, manholes. Model manholes made of closed-end aluminium cylinders are buried in a trench filled with loose saturated sand. The model is fully equipped with accelerometers, pore pressure transducers, and laser displacement transducers. The experiment is carried out under 20 g. A sinusoidal input motion was employed to investigate the uplifting mechanism under simple conditions. Results show that the amount of uplift is proportional to amplitudes of input acceleration, and the amount depends both on the ground water levels and density of backfill. A simple and quantitative method for estimation of the maximum uplift displacement proposed by the authors is verified with the results of model testing.

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記述言語：英語  

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記述言語：英語  

The effect of vertical loads on the lateral response of group pile is studied on the basis of soil-pile interaction nature. Coupled soil-pile system is idealized through two dimensional finite elements with soil models idealized by multiple shear mechanism of hyperbolic type. The developed numerical model has been verified by comparing the results with full scale pile group test results. Through comparative studies, it has been found that for a single pile and at a given lateral load, the lateral deflection decreases with the combination of vertical load. For the group pile, the vertical load effect depends basically on pile position and pile spacing to diameter ratio. © 2009 IOS Press.

DOI： 10.3233/978-1-60750-031-5-1251

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記述言語：英語  

Applicability of the two stage scaling relationship called generalized scaling law for centrifuge tests proposed by Iai et al. (2005) is investigated for dynamic response of flat layered media. In this scaling law, recorded physical model parameters are, firstly, converted to those in the virtual 1G field with scaling factor for centrifuge model tests, η. Then the parameters are further converted to prototype with scaling factor for 1G tests, μ (Iai, 1989). By using this scaling law, model tests with scaling factor (prototype/physical model) of 100 or much higher may be possible without encountering problems, e.g., scaling of granular material. The generalized scaling law in centrifuge modeling is investigated through dynamic response of compacted sand. In the experiments, a prototype is scaled down to 1/100 with 9 combinations of scaling factors of virtual 1 G and centrifugal field. Input motions are also scaled accordingly. Then the generalized scaling relation is applied to examine responses in the prototype scale. Responses compared in the present study are shear wave velocity, displacement, and acceleration. If the generalized scaling law is valid, these responses in the prototype scale are identical regardless of scaling factors. Results confirm the validity of the scaling relation of these physical parameters in a range of 40 G to 70 G of centrifugal accelerations. © 2009 IOS Press.

DOI： 10.3233/978-1-60750-031-5-664

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記述言語：英語  

Applicability of the two stage scaling relationship called generalized scaling law for centrifuge tests proposed by Iai et al. (2005) is investigated for dynamic response of flat layered media. In this scaling law, recorded physical model parameters are, firstly, converted to those in the virtual 1G field with scaling factor for centrifuge model tests, η. Then the parameters are further converted to prototype with scaling factor for 1G tests, μ (Iai, 1989). By using this scaling law, model tests with scaling factor (prototype/physical model) of 100 or much higher may be possible without encountering problems, e.g., scaling of granular material. The generalized scaling law in centrifuge modeling is investigated through dynamic response of compacted sand. In the experiments, a prototype is scaled down to 1/100 with 9 combinations of scaling factors of virtual 1 G and centrifugal field. Input motions are also scaled accordingly. Then the generalized scaling relation is applied to examine responses in the prototype scale. Responses compared in the present study are shear wave velocity, displacement, and acceleration. If the generalized scaling law is valid, these responses in the prototype scale are identical regardless of scaling factors. Results confirm the validity of the scaling relation of these physical parameters in a range of 40 G to 70 G of centrifugal accelerations. © 2009 IOS Press.

DOI： 10.3233/978-1-60750-031-5-664

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記述言語：日本語   出版者・発行元：京都大学防災研究所  

本研究では，砂のような粒状体の力学モデルとしてのひずみ空間での多重せん断モデルを基に，大変形解析(有限ひずみ解析)に必要なTotal Lagrangian(TL法)法，および，Updated Langrangian法(UP法)の両者による定式化を示す。大変形解析に必要な定式化においては，圧縮性を考慮した超弾性体の大変形解析理論を基に，これに，多重せん断機構および非線形性(カップリング項としてのダイレイタンシを含む)を盛り込んだ定式化を示す。

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記述言語：英語   出版者・発行元：AMER INST PHYSICS  

A simplified method to estimate the maximum uplift displacement of a manhole and settlements of backfill soil under liquefaction is proposed. The method is derived based on the mechanism of uplifting of a manhole under undrained condition of backfill soil. It also has a capability of estimating effectiveness of countermeasures against uplifting by considering excess pore water pressure ratio and/or unit weight of backfill soil. In the present study, however, estimation for the case of no countermeasure is verified through comparison with experimental results. Results show that measured uplift displacements and settlements are confined within the boundary predicted by the proposed method.

DOI： 10.1063/1.2963871

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記述言語：英語   出版者・発行元：SCIENCE PRESS BEIJING  

The paper describes an emerging methodology for evaluating seismic performance of geotechnical structures that extend over tens of kilometers along a coastal protection line. The challenging aspect in establishing this type of methodology for performance evaluation is in the fact that site-by-site detailed study is not practical. The paper proposed a performance-based approach utilizing simplified design charts that are newly developed based on a parameter study of effective stress analyses of soil-structure systems. The coastal protection lines over a distance of 70km along Osaka Bay Area, Japan, are used as an example to demonstrate the advantages of the proposed approach.

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記述言語：日本語   出版者・発行元：京都大学防災研究所  

本稿では，砂の力学モデルとしてのひずみ空間での多重せん断モデル(Iai＆Ozutsumi, 2005)に基づく線形弾性体の構成式を提案し，幾何学的非線形性を考慮した大変形解析(有限ひずみ解析)に必要な定式化を示す。本定式化では，体積ひずみと等方圧力，および，仮想単純モデルにおけるせん断ひずみとせん断応力との間に線形関係を仮定している。定式化を基に，有限要素法による数値解析に必要な離散化を行い，Total Lagrangian法，および，Updated Lagrangian法の両者によるプログラミングを実施することで得られた要素解析例を併せて示す。

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その他リンク： http://hdl.handle.net/2433/129308

記述言語：英語   出版者・発行元：AMER INST PHYSICS  

A simplified method to estimate the maximum uplift displacement of a manhole and settlements of backfill soil under liquefaction is proposed. The method is derived based on the mechanism of uplifting of a manhole under undrained condition of backfill soil. It also has a capability of estimating effectiveness of countermeasures against uplifting by considering excess pore water pressure ratio and/or unit weight of backfill soil. In the present study, however, estimation for the case of no countermeasure is verified through comparison with experimental results. Results show that measured uplift displacements and settlements are confined within the boundary predicted by the proposed method.

DOI： 10.1063/1.2963871

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記述言語：英語   出版者・発行元：EARTHQUAKE ENGINEERING RESEARCH INST  

Seismic intensity in the epicentral area of the 2003 Bam, Iran earthquake is estimated using a questionnaire survey conducted two months after the earthquake. The estimated average seismic intensity on the Japan Meteorological Agency (JMA) scale is 6.1 (VIII to IX in the MMI scale). The peak frequency of the horizontal-to-vertical spectral ratio derived from microtremor measurements conducted during reconnaissance is also compared with the seismic intensity. Collapse rates for various structure types, such as adobe, unreinforced/reinforced masonry, steel-frame, and reinforced concrete, are obtained by counting the number of demolished buildings within an area of about 50-m radius around an observation point. Results show large differences in collapse rates between unreinforced and reinforced masonry, and suggest the upper limit of seismic intensity that unreinforced masonry can sustain. This fact can be utilized for an initial damage assessment within affected areas after large earthquakes.

DOI： 10.1193/1.2790490

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記述言語：日本語   出版者・発行元：京都大学防災研究所  

地震時における自立式矢板護岸の動的変形挙動を把握するため，遠心模型実験および数値解析を実施した。数値解析においては，地震動が加わる前の矢板の初期拘束条件や，矢板・土要素間のモデル化の方法など，種々の条件を変化させ，解析条件の違いが解析結果に及ぼす影響について考察を行った。その結果，自立式矢板護岸の地震時挙動を精度良く予測するためには，地震動が加わる前の矢板の初期曲げモーメント分布に代表される，静的な応力状態を正確に再現することが必要不可欠であることが確認された。また，飽和砂地盤を対象とした場合，受働側の矢板・土要素間にジョイント要素を導入することで，解析精度が向上することがわかった。

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その他リンク： http://hdl.handle.net/2433/73397

記述言語：英語   出版者・発行元：京都大学防災研究所  

近年，実験模型の大型化が進んでいる。しかし，地盤-基礎構造物の相互作用問題について実大模型を作成し実験を行うことは，発破による液状化試験など特殊な事例を除き，現段階では不可能に近い。このため，遠心模型実験が用いられることが多いが，中小型の遠心模型実験装置では装置の容量や使用できる土槽の大きさなどによる制約がある。そこで，Iaiら(2005)は仮想的な1G場模型を考え，それをターゲットとして遠心模型実験を行い，実験結果に対し遠心場の模型相似則と1G場の模型相似則(Iai 1989)を連続して適用し実物スケールに換算する相似則を提案した。ここでは，これを「拡張型相似則」と呼ぶ。

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記述言語：英語   出版者・発行元：京都大学防災研究所  

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記述言語：英語   出版者・発行元：京都大学防災研究所 / Disaster Prevention Research Institute Kyoto University  

飽和砂地盤上の盛土の動的変形挙動を調べるため，遠心模型実験，および多重せん断ばねモデルによる有限要素解析（FLIP）を行った．本研究で対象とした盛土は，堤体高さ3ｍ，天端と下端の長さが4ｍと11.5ｍ（実物スケール）である．また下部地盤の層厚は5ｍである．緩詰地盤を対象とした数値解析では地盤のN値=1に対応するパラメータを用いた場合に，天端の沈下量が実験結果と良く一致した．数値解析の結果，入力加速度が大きいほど，盛土下部の非液状化領域が大きくなり，それがくさびとなって周辺の液状化地盤を押しのけるため沈下量が大きくなるという，一見すると直感的ではない変形メカニズムが推察された．

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その他リンク： http://hdl.handle.net/2433/26628

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記述言語：日本語   出版者・発行元：公益社団法人 地盤工学会  

杭・地盤系の動的応答の位相関係を明らかにするため遠心力場(40G)における模型実験を実施した。実験は正弦波加振で行い,地盤条件(乾燥,飽和),杭の条件(杭頭に付与する質量の有無)などを変えて,延べ8ケース実施し,杭頭慣性力と地盤変位の位相関係に着目してとりまとめた。この結果,杭・地盤系の固有振動数が地盤の固有振動数より小さい場合,杭頭慣性力の位相は地盤変位のそれに対して遅れること,逆に,杭・地盤系の固有振動数が地盤の固有振動数よりも大きい場合には,杭頭慣性力の位相は地盤変位のそれに先行することが明らかになった。これらの結果について,地盤および杭・地盤系をそれぞれ独立した1質点系とみなして考察を加えた。

DOI： 10.11512/jiban.JGS39.0.1789.0

J-GLOBAL

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記述言語：日本語  

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記述言語：日本語   出版者・発行元：公益社団法人 地盤工学会  

本研究では、杭基礎を対象として、杭の変位に伴う水平断面内での杭周辺地盤の変形挙動を詳細に調べるために静的引張り試験を実施し、解析結果と比較した。実験は、杭を模擬する直径5cm、高さ4cmのテフロン製の円柱を、乾燥砂又は飽和砂地盤に設置し、ワイヤーを介して水平方向に引張る。用いた杭は単杭、および杭間隔の3倍と5倍の群杭とした。このときの杭周辺地盤の変形をビデオカメラとマイクロスコープを用いて記録し、解析と比較した。その結果、杭近傍の地盤は杭後方に回り込むように変位すること、群杭の場合杭間隔が小さいと、その間の地盤は杭と一体となって動くことなどが観察された。また解析によってもその挙動が再現された。

DOI： 10.11512/jiban.JGS39.0.1529.0

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記述言語：日本語  

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記述言語：英語  

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記述言語：英語  

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記述言語：日本語  

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記述言語：日本語   出版者・発行元：自然災害科学会  

CiNii Books

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その他リンク： http://id.nii.ac.jp/1141/00113530/

記述言語：日本語   出版者・発行元：自然災害科学会  

CiNii Books

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その他リンク： http://id.nii.ac.jp/1141/00113410/

記述言語：英語  

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記述言語：英語  

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記述言語：日本語   出版者・発行元：公益社団法人 地盤工学会  

大地震時における群杭の挙動を明らかにする第2段階の検討として、遠心力場で単杭および群杭の振動実験を行い、群杭効果に関する基礎的なデータを得た。杭径30cm、杭長10mの鋼管杭を縮尺1/40でモデル化した。杭頭は自由端、杭間隔は杭径の3倍で3x3に配置された群杭の乾燥砂および飽和砂地盤中の動的挙動を調べた。乾燥砂を用いた実験では、杭径の約30%の変位を与えた静的実験と比較した結果、振動実験の方が地盤の抵抗が小さく、同一荷重に対し大きな変位が発生した。一方、飽和砂を用いた実験では、単杭の振動実験と比較すると、荷重変位曲線の傾きが小さくなり、液状化地盤中においても群杭効果と推察される結果が得られた。

DOI： 10.11512/jiban.JGS38.0.1443.0

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記述言語：日本語  

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記述言語：日本語   出版者・発行元：公益社団法人 土木学会  

墓石の転倒に関する研究は古くから行われているが, 墓石の回転現象と地震動特性との関係を明らかにした研究はほとんど見当たらない. そこで本研究では, 強震時の直方剛体の動的挙動, 特にその鉛直軸まわりの回転挙動が生じる原因を, 振動台模型実験及び3次元DEM解析を通して検討した. 直方剛体の回転挙動は, 振動の卓越する方向に回転する挙動と, 入力波の粒子軌跡が回転することによって剛体が逆方向に回転する挙動の2つに分類できることがわかった. さらに, 三陸はるか沖地震の際に回転した墓石の極く近傍で観測された加速度記録を用いてその回転挙動を再現した. これらの検討の結果, 特殊な場合を除けば, 墓石の回転方向は地震動の加速度粒子軌跡の回転の逆方向を表わしていると結論された.

DOI： 10.2208/jscej.1998.598_287

CiNii Books

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