We have been investigating the site characteristics of strong motions at engineering base layer in Kanto region. The site characteristics of strong motions are obtained as the geometric averaged ratios of acceleration response spectra between the observed data and calculated values estimated by the existing empirical attenuation relations. There exist significant differences in the variances of acceleration response spectrum ratios between the mountain area and the plain field. In this study, we focus on the variances of acceleration response spectrum ratios. The analysis shows that the variance of acceleration response spectrum ratios can be reduced by the realignment of observed data with respect to the focal region. In addition, we present the possibility of effect of depth from the engineering base layer to the seismic bedrock on the variances of acceleration response spectrum ratios.

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 This paper proposes the estimation method for nonlinearity of a whole ground with using only input and output records of a large earthquake. Natural period, T_g and strength of whole ground, K_f which is propose by the authors, are selected as important indexes for expressing ground nonlinearity. It was confirmed that the ground motion at surface are much influenced by these two indexes. We, therefore, examined the estimation method for T_g and K_f by using input and output record of large earthquake in this paper. Applicability of the method is confirmed by numerical simulations. By using proposed method, nonlinear deformation characteristics of a whole ground can be estimated using only observation records without detailed soil profile of each layer.

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 An earthquake with a moment magnitude of 7.8 occurred at 11:56 NST (local time) on 25 April 2015, in the central part of Nepal (Gorkha). First damage surveys were conducted at the affected area during 26 May to 21 July three times by the team of NIED. This paper outlines the findings of the surveys on the various spects of the earthquake disaster in the Kathmandu Valley. Some of the observations are that the main damage was to masonry buildings especially with mud mortar, but limited to RC buildings, and the historical buildings with renovation showed smaller damage. Thus, low cost retrofitting method will be necessary for mainly in suburb housings rich in masonry buildings with mud mortar. According to the comparison with the past risk assessment project results (JICA, 2002), these were found that the effects by the 2015 Gorkha earthquake were less than those due to the 1934 Bihar-Nepal Earthquake, and the similar features were found in both the 1833 Earthquake and the 2015 Gorkha Earthquake. Primarily, the first survey was to collect timely raw information on the damage to buildings and to confirm the availability of data and their sources for subsequent surveys. The motivation for the thread survey was to obtain ground truth data to calibrate. These may help the future earthquake disaster mitigation efforts.

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 In the past earthquakes, serious damage to plain concrete piers of railroad bridges has been caused. The typical damage is horizontal gap at the cold joint of a pier and falling down of concrete pieces from the pier under the cold joint. It is necessary to understand the damage occurrence mechanism and to develop effective seismic measures to prevent serious damage in the future earthquakes. With this background, this study analyzed the seismic behavior of a plain concrete pier using the refined DEM, investigated the damage occurrence mechanism, and verified the validity of two seismic measures. It was found that the friction and collision forces from the pier above the cold joint caused the tensile failure of the pier under the cold joint. The effectiveness of two seismic measures was found to be limited since the concrete contacting the reinforcement material suffered from damage.

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 The author previously proposed prediction equations for uniform durations of JMA seismic intensity assuming that intensity is observed or predicted exogenously. Furthermore, by incorporating GMPE for intensity and its uncertainty, a consistent scheme for prediction of intensity and duration was proposed. However, application and validation of the proposed scheme to an actual earthquake has not been performed. In this study, the proposed scheme has been applied to the 2014 Nagano-ken Hokubu Earthquake (M_w=6.2). Durations estimated using observed intensity are highly correlated with observed durations. Those based on predicted intensity vary widely, however, dispersions are found to be unbiased around the observed durations. For comparison purpose, duration prediction equations obtained by direct regression are also derived and validated. As a whole, advantage of the suggested scheme has been validated.

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 Evaluation with high accuracy of ground motion at a damaged site is very important to analyze collapse mechanism of structures such as wooden houses. A serious disaster occurred during the 2014 Northern Nagano Prefecture Earthquake. However, there were no strong motion observation stations at the damage sites of wooded houses during this earthquake. In this study, the seismic waveforms at Kamishiro District, where a serious damage to wooded houses occurred, were estimated with high density based on empirical site amplification and phase effects. The estimated seismic waveforms will be useful for rational safety assessment of wooden houses.

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 During a scenario earthquake with M_W9.0 along the Nankai Trough, not only strong motion but also huge tsunami is predicted in Hirokawa Town, Wakayama Prefecture, Japan. In this study, first, based on the empirical relationship between microtremor H/V spectrum and site amplification factor, the site amplification factors from seismic bedrock to ground surface at the 476 sites in the tsunami attack area were evaluated. Seismic waveforms in the area were then predicted with very high density based on the SMGA models considering the empirical site amplification factors. Using the detailed distribution of JMA seismic intensity and difficult time for tsunami evacuation due to the predicted seismic waveforms, finally, we discussed the influence which the action of the strong motion has on evacuation.

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 This study investigates the relationship between the damage ratios of regional roads and tsunami inundation depths after the 2011 off the Pacific coast of Tohoku earthquake. This study focuses on the damage incidents to the roads excluding elevated roads, bridges, and tunnels, and the damage ratios are defined as the number of damage incidents per kilometer. The damage dataset compiled by the Ministry of Land, Infrastructure and Transport was employed in this study. According to the results, four kinds of fragility functions for regional roads are proposed considering the differences of topographical features. The classifications are validated due to the results of numerical simulation of tsunami propagation.

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 In this research, reference displacement index L⁽ⁱ⁾ is proposed to determine the layer quantitatively where the dynamic soil properties test is needed for seismic design. In the proposed method, the nonlinear static analysis was conducted repeatedly by using a general non-linear constitutive law and standard parameters of soils. The index L⁽ⁱ⁾ was calculated for each stratum that represents the contribution of the layer to the total force-displacement behavior of the soil deposit. The dominant soil layer will be then determined by comparing the indices each other, and it is actually a location where the soil properties should be carefully investigated. In order to evaluate the efficacy of the method, the index L⁽ⁱ⁾ were evaluated for many soil deposits with various stratum properties. It was confirmed that the surface ground motion was significantly affected by the properties of a soil layer whose index L⁽ⁱ⁾ was relatively higher. The proposed method is advantageous over traditional methods in the aspect that it gives the stable results independent of the earthquake motion. In addition, L⁽ⁱ⁾ could be calculated even if only a limited information is available, such as N-value and soil classification. It follows that this method provides the quantitative measure to select the layer that in-situ dynamic soil properties test is required

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 We propose quality assurance procedures of automatically constructed models for seismic response analysis. In these procedures, models of different fidelity are used, and the quality of a higher fidelity model is examined by comparing its response with a lower fidelity model. A key issue is the consistency of the models of different fidelity, and the meta-modeling theory is used to guarantee the consistency. As an illustrative example, models of different fidelity are automatically constructed for a bridge structure, and it is shown that the developed procedures are applicable to them. The quality of the automated solid element model that is of highest fidelity is examined.

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 This study developed a numerical model to estimate the period of restoration work for expressway after an earthquake. A series of logistic regression analyses was performed based on the dataset after the recent earthquakes: the 2004 Mid-Niigata earthquake, the 2007 Chuetsu offshore earthquake, the 2008 Iwate-Miyagi Nairiku earthquake, and the 2011 Great East Japan earthquake. The model constructed by this study had an excellent discriminating ability based on the assessment of receiver operating characteristics curve. The model was applied to estimate the restoration period of expressway after a scenario earthquake which may occur in the Nankai Trough.

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 The 2011 Great East Japan Earthquake caused significant soil liquefaction, and many residences were damaged as a result of associated settlement and inclination. This highlighted the importance of seismic countermeasures for small-scale structures. One such measure involves driving logs into the ground to add density. As trees store carbon during growth, logs placed underground below the water table are not prone to deterioration. Based on this characteristic, subterranean log piling represents a dual measure against both global warming and liquefaction. Since log piles can be set only in ground around existing houses rather than directly beneath them, the effect of the resulting densification is limited. However, rigidity added using this approach and the associated partial densification of soil can be expected to have a certain effect in suppressing ground deformation. In this study, shaking table tests were carried out to investigate the effect of log piles placed around existing houses. Also, numerical analysis was conducted to clarify the effects of this technique. As a result, it is found that the settlements and tilts of houses were mitigated by this method.

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 Video movies of the tsunami and the numerical simulation have been evidences to evaluate the tsunami-induced force to the bridges in previous researches. However, it is still difficult to identify the bridge behavior up to the stage of wash-out of superstructure. This paper focuses on the damage traces observed at the bearing supports and viscous dampers equipped in Kesen Bridge, so that the behavior of Kesen Bridge subjected to the tsunami-induced force is clarified precisely based on facts of those damage traces.

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 This study investigates the damage ratios of gas distribution pipelines in Tokyo Metropolitan area after the 2011 off the Pacific coast of Tohoku earthquake. The relationship between the damage ratios and spectrum intensities (SI), which were observed by a real-time earthquake monitoring system, SUPREME, operated by Tokyo Gas Co., Ltd., is evaluated. A fragility function for gas supply pipes is newly developed by this study. The effects of topographical conditions on the damage situations of gas distribution pipelines are also investigated. More damage incidents to gas pipes are expected in the valley bottom lowland.

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 In this paper, hybrid effect by base isolation and viscous damper devices is explained in order to reduce seismic response for widening existing viaducts. Authors carried out nonlinear time-history seismic response analyses under the level II earthquake. The behavior of steel girders and piers, the interaction and collision between girders, and effects of seismic devices are described in details. It is confirmed that viscous damper devices avoid collision and reduce the frequency of collision between girders and base isolation devices reduce the influence on base of piers. It was also found that the hybrid-usage of base isolation and viscous damper devices could be effective for widening existing viaducts.

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 Nowadays, there had been numerous researches about deformation behavior of pipelines crossing faults so far, but there had been few researches on the countermeasures. It has been observed that a pipeline crossing fault was deformed as Z-shape. Therefore, as a countermeasure for water pipeline for crossing faults, we have developed a steel pipe for crossing a fault (SPF). The SPF is capable of maintaining the water flow function and of avoiding the cracks, thanks to wave-shaped pipe section. The wave-shaped pipe section is initially installed in the positions where the plastic hinges occur.
 This paper shows a math formula for identifying the plastic hinge positions, based on the results of deformation of buried steel pipe on fault displacement, according to the split-box experiments and numerical analysis.

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 After the 2011 Off the Pacific Coast of Tohoku Earthquake in Japan, it was found that liquefaction can appear at multiple times in the same sites. This issue created a great concern about the reoccurrence of multiple-liquefaction in the future earthquakes. In this study, a series of cyclic simple shear tests was performed on dry Toyoura sand while keeping the specimen volume constant using a stacked-ring shear apparatus. In order to study the behavior of multiple-liquefaction under small to large strain levels, the same specimen was sheared at different levels of maximum shear strain double amplitude on each liquefaction stage. In addition, in order to investigate how the occurrence of previous liquefaction may affect the soil behavior during future liquefaction stages, an analysis based on dissipated energy was conducted.

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 Ideal frequency dependent shear modulus and damping ratio characteristics are proposed through the analyses of vertical array several strong motion records by the parametric study. At first, FDEL and DYNEQ, equivalent linear methods developed to improve the disadvantage of SHAKE by considering frequency dependency of material property, are examined and are shown to overestimate amplification at high frequency range. Then frequency dependent functional shape is examined by optimizing the response. It is concluded that small amount of damping is necessary to suppress overestimation of amplification at high frequency, which corresponds scattering attenuation due to inhomogeneity of the ground. It is also pointed out that functional shape is better to be smooth. Optimized parameters give good result for both convolution and deconvolution analyses.

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 It is difficult to evaluate site amplification factor analytically because site amplification factor is affected by several factors such as three dimensional deep subsurface profile. Site amplification factors have been evaluated by spectral inversion using strong motion record in the previous study. Therfore, site amplification factor has not been evaluated precisely at sites without strong motion observation.
 This study aims at proposing a simple estimation method of site amplification factors by use of deep subsurface profile. Amplification factors at low frequencies and peak amplification factors were estimated by the stochastic analysis. Estimated amplification spectra were obtained by modifying the amplification spectra assuming horizontally layered deep subsurface profile. Applicability of the proposed method was discussed.

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 It is difficult to evaluate site amplification factor analytically because site amplification factor is affected by several factors such as three dimensional deep subsurface profile. Therefore, site amplification factors have been evaluated by spectral inversion using strong motion records and those at sites without strong motion observation records have not been evaluated precisely.
 In this study, evaluation method of site amplification factors at dense strong motion observation area was discussed. Site amplification factors for the low frequency range were evaluated by using both three dimensional finite difference analysis results and empirical site amplification factors. On the other hand, site amplification factors for the high frequency range were evaluated by the mean amplification factors considering geomorphologic condition. Applicability of the proposed method was discussed.

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 It is vital to improve the strength of railway viaducts which are an important part of a transportation system. One promising technique is to reinforce viaducts columns with spiral rebars inside axial reinforcing bars. This technique has already been tentatively applied in the construction of some railway viaducts. It has been empirically shown in previous experimental analyses that a column reinforced with a spiral rebar, a so-called spiral column, has a large deformation capacity. However, the level of seismic force required before railway viaducts with spiral columns reach the ultimate state is still not clear. In this paper, the ultimate strength of railway viaducts with spiral columns were quantitatively evaluated based on nonlinear dynamic analysis.

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 We study variations on predicted ground motions of Mw6.8 crustal earthquake caused by concealed faults.
 In this article, while we evaluate basic source parameters based on the Recipe for Strong-motion Prediction, we consider variations on dip angle, position of asperities and rupture starting point, average slip of asperities, short-period spectrum level and rupture velocity.
 Estimated near-fault ground motions using the above parameters are compared with the ground motion using the parameters established by the committee of cabinet office in Japan.
 In conclusion, the spectrum of ground motion using parameters of the cabinet office is generally within the range between that of 90% non-exceeding probability and the average of 345 cases considering variations.

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 The aim of this study is first to investigate the relationship between liquefaction potential and liquefaction-induced road subsidence that occurred in Urayasu City in the 2011 off the Pacific Coast of Tohoku Earthquake, and then to develop a new hazard map reflecting this relationship, which provides expected liquefaction-induced road subsidence. The liquefaction potential distribution in Urayasu City during the particular seismic event of this 2011 earthquake was evaluated with an available geotechnical data set and the values of liquefaction-induced road subsidence at 251 locations were obtained from a set of the Digital Surface Models (DSMs) from airborne LiDAR surveys before (2006) and after (2011) the 2011 earthquake. Estimated liquefaction potential values and corresponding values of liquefaction-induced road subsidence show that the subsidence values are larger in general for residential roads than those for the main roads given the same value of liquefaction potential. The obtained relationship between values of liquefaction potential and road subsidence are reflected upon a newly developed liquefaction hazard map for Urayasu City.

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 In this paper, seismic responses of RC piles and the hybrid structural footing foundation of the double racket-type steel piers are described by 2-D static and dynamic soil-structure coupled nonlinear FEM analyses in detail. Authors verified that the newly developed structure had enough load bearing capacity when the level II earthquake load was applied in the longitudinal and transverse directions. It is founded that shear deformation around the heads of the existing RC piles is not significant and the hybrid structural footing is also effective to reduce the stresses in the lower surface of the existing RC footing. It is confirmed the overall pile and footing foundations could keep stable even if some parts of the RC piles yielded under the level II earthquake.

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 The ground which needs consideration for liquefaction is increasing because the design seismic wave for infrastructures is tend to be severer. Many existing studies have mentioned the relationship between the occurrence of liquefaction by earthquake and liquefaction judging method. Although, the relationship between the structural damage and the potential of liquefaction index is less studied.
 We investigated the structural damage and the occurrence of liquefaction where strong seismic motion was observed along the Shinkansen railway viaducts in the 2011 off the Pacific Coast Tohoku Earthquake, and the Mid Niigata Prefecture Earthquake in 2004.
 The result shows that the relationships between the occurrence of liquefaction and the potential of liquefaction index is similar to existing studies, but those between structural damage and that are less harmonic. And we confirmed that many railway viaducts which had not been designed for liquefaction were not damaged on the liquefaction grounds which could be judged by the potential of liquefaction index.

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 A new type of BRB named RP-BRB (Rippled Plate Buckling Restrained Brace) is investigated. The core member of RP-BRB is a rippled plate instead of flat plate in BRB. Compared to BRRP which was studied previoulsy, RP-BRBs possess long and multiple-wave core members. Thus special care must be given to prevent the unstable load-deformation characteristics due to local/overall buckling of the core members as well as friction effects between the core member and the restraining members.
 In this study, RP-BRB specimens with two special devices are tested: 1) a pair of projecting bars bolted to both sides along the core member (the guide series test) , and 2) semi-cylindrical shape spacers set inside the ripples (the space series test). Cyclic loading tests are carried out using test specimens possessing various numbers of either the projecting bars or the spacers. Then loading and deformation capacities, hysteretic characteristics, local strains occurred in the core members are examined and the efficiency of using the special devices is demonstrated. Moreover, material properties of the rippled core plate are determined from tensile tests, and its validity is confirmed by comparison between the analysis and test.

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 Material Point Method (MPM) is one of the mesh-free or grid-free numerical methods. In recent years, the MPM has been applied to the Geotechnical field because we may simulate easily for large deformation phenomena of ground with the exact Dirichlet boundary conditions by using this method. However, some inexplicable fluctuations of elastic energy have often occurred in the MPM simulations. In this paper, we propose a novel numerical technique in order to suppress the energy fluctuation phenomena. In this technique the Moving Least Squares Method is applied to the strain field of particles as a smoothing interpolation scheme. In order to verify the proposed technique, we showed some comparative studies in the dynamic problems.

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 In the current seismic design of a buried pipe, the axial ground restraint force between the pipe and the ground is modeled as a bi-linear function with respect to the relative displacement. In other words, the soil friction determining the ground restraint force is assumed as constant regardless of the pipe moving velocity. However, it is thought that the soil friction depends on the pipe moving velocity because of the relocation of the soil particles. This study attempted to examine the velocity-dependency of the soil friction with the pipe pilling experiment of the small-scale soil box. As a result, the frictional force grows larger in accordance with the pipe moving velocity.

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 The damage of underground structures such as tunnels transecting the fault are reported in some recent earthquakes. But there are few papers in which parametric studies about the influence of fault conditions on structure response are conducted . So in this paper, the influence of the fault angle, the displacement angle and the stiffness ratio between ground and structure on the response of circular cross-section underground structure subjected to fault displacement is studied by parametric studies using 3D FEM. As a typical result of studies, it is verified that in cases where the fault angle deviates from perpendicular, the axial stress of structure dominates and its maximum value is given when the fault angle is about 45°.

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 Multiple arch dam is complex structure which is composed of more than two arch dams. As for seismic safety evaluaton for multiple arch dam, how to consider mutual effects among plural arch dams is one of the difficult problem. In this stuty, we made two kinds of three dimentional analytical models, one is single dam model and the other is dual dam model. As a result, the dynamic tensile stress evaluated by the single dam model became smaller than that evaluated by the dual dam model. Consequently, it is considered that the mutual dynamic effects among plural arch dams should be taken into account in order to exedute accurate and reliable evaluation.

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 It is difficult to evaluate site amplification factor analytically because site amplification factor is affected by several factors such as three dimensional deep subsurface profile. Site amplification factors have been evaluated by spectral inversion using strong motion records in the previous study. Therfore, site amplification factor has not been evaluated precisely at sites without strong motion observation.
 In this study, site amplification factors at several strong motion observation points in Kyoto basin were evaluated by three dimensional finite difference analysis by modeling deep subsurface profile. Site amplification factors obtained by analysis were compared with those by spectral inversion and accuracy of the results by analysis was discussed. It was shown that the site amplification factor was evaluated more precicely by using both analytical site amplification factor and empirical site amplification factor. In addition, new evaluation method of the site amplification factor in the range up to 6Hz was proposed. Applicability of the proposed method was discussed.

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 The purpose of this study was to verify the fault modeling in the source region of the 1940 Shakotan-Oki earthquake, which was caused by the active marine faults offshore Japan. The tsunami wave heights simulated from fault models proposed by previous studies were lower than the observations, which made it difficult to explain the historical tsunami records of the 1940 Shakotan-Oki earthquake. However, the application of appropriate slip magnitudes in the fault models may be able to explain these differences. In this study, we constructed a new fault model using marine seismic industry data and geological and geophysical data compiled by the Off shore Fault Evaluation Group, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), as part of the Project for off shore fault evaluation, the Ministry of Education, Culture, Sports, Science and Technology (MEXT). The marine seismic industry data included information from a new fault that was located to the north of the existing fault investigated in the previous studies. We adjusted the geometrical continuity of these faults, whereby the magnitude of the fault slip was increased. We applied the standard scaling laws based on strong ground motion for the fault parameters. The validity of the fault model was examined from a comparison of tsunami wave heights in the Japanese coastline between historical observation records and the tsunami simulation analysis, and quantified with scale and variance parameters referred to as Aida's K and κ. Based on the results, the simulated tsunami wave heights using the new model approached the heights observed in the historical records, thus indicating the validity of the model for accurately modeling the source region. In future studies, more reasonable results are expected by considering asperities and the fault parameters located in the shallow part of the source region.

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 The purpose of this study is to obtain the seimic response of the abutment on the liquification ground. Especially, the bending moment of the piles and the horizontal displacement of the abutment are focused on. Firstly, from the analytical results by not considering the girder, the abutment lean to forward and the displacement and the back foundation settlement become large. Secondary, from the analytical results by considered the girder, the displacement of the abutment and the settlement of back foundation become very small. But the bending moment of the piles at the pile got the large value. The girder worked as a stopper for the abutment leaning.

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 In recent years massive earthquake which was not taken into consideration in the conventional seismic design come to be observed in various place. Consequently, examination of earthquake proof repair considering the massive earthquake is needed. In order to solve the problem of fatigue damage due to the increase of the traffic load or the damage caused by the water leakage from the expansion joints in floor framing girders of the existing suspension bridge, the continuous structure of the floor framing girders and construction of new seismic system are effective.
 In this study, two simplified models focused on the center span and the structural model that simulate the entire of the object bridge were created. The dynamic response analysis for Level2 earthquake motion by using these three structural models to evaluate the response of floor framing were performed. As a result, applicability of evaluation of response by using the simplified structural models was confirmed.

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 The log piling method is one of a liquefaction countermeasure technique whose principle is to densify loose sand layer. This paper deals with a proposal of technique of ground improvement by installing a timber got from demolished wooden structures instead of the log. First, it was clarified that a lot of timbers would be used instead of logs by investigating the dimensions of timbers which were got from demolished wooden houses. Second, small-scale shaking table tests were carried out to clarify difference of effectiveness between timbers and logs when they are used as a liquefaction countermeasure for a lightweight structure such as a residential house. As a result, the effectiveness of timbers against settlement of house was equal to logs. Furthermore, vertical and lateral displacements of house in case of timbers were smaller than that of logs.

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 On March 11, the huge tsunami caused by the great east Japan earthquake devastated the Pacific coastal area of north-eastern Japan. After the earthquake, the disaster prevention and mitigation against Tsunami and earthquake is being reconsidered both in the ‘hard’ method like protective infrastructure constructions and in the ‘soft’ method including disaster evacuation education of policy maker and citizens. Accurate Tsunami simulation may become a useful tool for establishing a new Tsunami prevention guideline. In this study, we have developed a new 3D tsunami inundation simulation tool by the SPH method, which is one of meshless particle analysis. In our developed tool, geography including the outline of each building is modeled from data of the Geographic Information System in a high spatial resolution with high accuracy. In addition to the newly developed preprocessing tool, a new post-processing ‘photo realistic visualization’ of the particle simulation result is proposed in order to utilize the numerical simulation for the tsunami disaster evacuation education and the other ‘soft’ disaster prevention.

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 Due to the 2011 Great East Japan Earthquake, some seismic isolation bridges were severely damaged by ground motion and cracks of isolation bearings were observed. In this paper, one of the damaged bridges was picked and dynamic analyses were conducted to clarify the cause of damage of the bridge. As a result of the reproduction analyses of the bridge using the estimated ground motion based on aftershock observations, it is estimated that the isolation bearings were damaged by shearing and vertical force due to rocking vibration of the superstructure.

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 In order to clarify the possibility of slope failure at existing nuclear facilities, the failure behavior based on the results of the shaking table tests under 1G field of the slope model is analyzed and the failure mechanism is clarified. Secondly, the applicability of the Material Point Method as an assessment method of the behavior is made clear. The slope model was made into 1.0 m in height, and 45 degree in inclination. The record observed at JMA Kobe by The Southern Hyogo prefecture earthquake in 1995 was used for shaking as well as the sinusoidal wave. It was found that a slip surface was formed due to the increased width and localization after connecting each area where a large shear strain was generated. In addition, it is found that the formation process of the primary slip surface which observed in the tests is properly simulated by MPM analysis.

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 On September 10, 1943, the Tottori earthquake occurred in the east of Tottori prefecture, and generated serious damage in Tottori city. We estimated subsurface velocity structure of damaged school sites in Tottori city using microtremor single station observation and array observation. Then we evaluated strong ground motion of the Tottori earthquake using stochastic green's function method at the sites. We found that predominant periods of response spectrum at heavily damaged sites agree with natural period of wooden building, and that estimated ground motions at damaged sites have large amplitude in period range between 1 to 2 sec, than lighter damage sites.

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 Due to noticeable subsidence of ground seen in a wide area of the Tohoku district caused by the 2011 off the Pacific coast of Tohoku Earthquake, port and harbor facilities became difficult to use as the sea level becomes too high during high tide. Necessary measures including level rising of quay walls were undertaken. However, subsequently, quay walls at some places became too high due to the increased ground elevation. A similar phenomenon was seen in Kochi city after the 1946 Showa Nankai Earthquake. People suffered from long lasting inundation there.
 In order to obtain beneficial knowledge for the next predicted mega earthquake, this study observes recovery process from the crustal movement caused by the Tohoku Earthquake using GEONET data provided by the Geospatial Information Authority of Japan. Results showed that immediate ground elevation occurred after the subsidence at some areas while subsidence continued for a time after the main shock until level rising began at some other areas. For areas where immediate ground elevation occurred after the subsidence, recovery process from subsidence was described well with the fitting function of exponential decay type. However, 1 to 3 years amount of data after the main shock may be needed to identify the time constant which determines the shape of the exponential decay curve.

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 Evaluation of seismic performance on buried pipeline changes whether the pipe slips against the surrounding soil or not. When slippage takes place, stress and strain concentrate to junctions and bends. Important factors of slip or not-slip are critical shear stress of soil (τ_cr) and elasticity of pipe materials. As there were few reports of experiments about polyethylene pipe(HPPE), we conducted the experiments to investigate the performance of HPPE. Our results obtained are : (1) τ_cr of HPPE with EF coupler is around 11.7kN/m² under the 60cm of backfilling soil. Therefore we adopted τ_cr of 10kN/m² which comes from the experiments of steel pipe, although a large difference of elasticity between HPPE and steel pipe. This means the existing seismic design method of buried pipeline can be applies to HPPE. (2) we found, however, that even HPPE can slip a little in solid ground because of the short wavelength. Then we have to estimate the influence of slippage against junctions and bends to confirm the seismic design method of HPPE.

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 Residential area of Maihama, Chiba City has received extensive damage by the liquefaction in 2011; The Great East Japan Earthquake. Chiba City immediately set up liquefaction Management Committee, Groundwater Drawdown Method was selected from the results of the experiment and investigation. However, exaction to place the water permeable pipe to drawdown the water from the ground generated a new problem; Ground Deformation.
 Therefore the authors have developed a new mechanism of placing the water permeable pipe by the Jacking method, experiments were carried out and analyzed over a period of 9 months in a park, verifying that the jacking method and the open cut method have the same effect, the study results are included in this paper.

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 In order to contribute to the establishment of the “anti-catastrophe” design concept of structures, the design standards for railway and port structures are reviewed, with special reference to their recent trends. Design examples are presented in which “anti-catastrophe” design concept is considered implicitly or explicitly both before and after the 2011 Great East Japan Earthquake. For the railway structures, devices have been developed for the “anti-catastrophe” design. For the port structures, efforts are being made to improve the performance of breakwaters after they are affected by extreme tsunamis. In the “anticatastrophe” design, it is important to understand the performance of a structure or a structure-environment system for extreme external forces.

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 It is requested to implement the concept of ”anti-catastrophie” property in the seismic design codes. It is not, however, a straight forward task because ”anti-catastrophe” concept has various significant differences from existing design codes. This paper identifies problems of the development of ”anti-catastrophe”- oriented seismic design codes, and proposed a new concept of ”category 2.” A framework of design code with ”category 2” is also presented. We also discussed conditions required for the society and government to make such new design codes effective, based on theoretical framework of risk governance and proposed several practical policies.

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 In order to perform the large tsunami simulation effectively, multi-scale tsunami simulation having both advantages of two-dimensional tsunami analysis based on the shallow water equation and three-dimensional tsunami analysis is being developed. The authors have selected the three-dimensional particle method as three-dimensional analysis method and proposed a new boundary treatment which can manipulate measured values in the pre-analysis by two-dimensional tsunami analysis. In this study, a matrix array shaped virtual wave-making plate is enhanced as an improved boundary treatment method for multi-scale tsunami simulation within the framework of the particle method, and then the accuracy and adequency has been investigated through a three-dimensional numerical example. Finally, a three-dimensional tsunami run-up simulation, in which the inflow condition is given by a two-dimensional shallow water solution, is conducted at Minami-Sanriku-cho in the 2011 Tohoku earthquake tsunami by using proposed method in order to validate the accuracy.

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 This study investigates the effects of drained or undrained cyclic loading history on small strain shear moduli and liquefaction resistance of Toyoura sand. Specimens with relative density of about 50% were subjected to isotropic consolidation up to 100 kPa, followed by drained cyclic loadings under triaxial condition with constant vertical strain double amplitude of 0.1%. In order to investigate variation of the small strain shear moduli and liquefaction resistance of the specimens caused by the different number of cyclic loading histories, a series of dynamic measurement by trigger and accelerometer method was conducted. It was found that the small strain shear moduli of the specimen increase with increase in the number of drained cyclic loading history, and there is a good correlation between the small strain shear moduli and liquefaction resistance. In adition, in order to obtain a lower limit of liquefaction resistance, another series of experiments were performed on specimens which have several liquefaction histories. The result shows that the smallest values of the small strain shear moduli and liquefaction resistance of the specimen were measured at the second stage of liquefaction test. Consequently, we found upper and lower limits of the small strain shear moduli and liquefaction strength of Toyoura sand specimen with relative density of about 50%.

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 During the 2011 Great East Japan Earthquake in Japan, extreme liquefaction caused extensive damage to residential houses in the Kanto Plain region and resulted settlements and tilts larger than that was observed during the past earthquakes. This paper deals with a proposal of ground improvement technique by installing logs into loose sand layer as a soil liquefaction countermeasure for existing residential houses. First, a demand for countermeasure of residential houses and reasonable cost of construction were shown by questionnaire surveys . Next, small-scale shaking table tests were carried out to propose how to apply the technique of log pilling around existing residential house. As a result, the magnitude of settlements of the house which was improved by log piling with an inclination and the fixed top of logs became quite small.

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 In this paper, pipes reinforced by concrete are focused. This reinforcement method is applied to when telecommunication conduits are buried shallowly. The purpose of this reinforcement is to protect pipes and inner cable from other construction works. Stress by seismic wave on these section have not been evaluated quantitatively, though these sections tend to be damaged from past earthquake experience. For quantitative evaluation of this section during an earthquake, soil tank test was carried out to find out behavior of the section of pipes reinforced by concrete in ground. From the soil tank test, it is clarified that larger ground restraint force is exerted on the section of pipes reinforced by concrete compared to usual pipe section.

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 This paper describes the damage to RC rigid frame viaducts caused by the 2011 Great East Japan earthquake. In this study, a three-dimensional dynamic nonlinear analysis is carried out to investigate the extent of seismic damage of Daiichi Nakasone Viaduct columns with the scenario earthquake. The mechanism of the damage to each column members (side part of columns and middle part of ones) and the dynamic behaviour of the structure are also studied. Inparticular, the reason of the different degrees of damage in side and middle columns is considered in detail. The analytical results show that the greater rotational mode of deformation caused by the acceleration and displacement response in the perpendicular direction in the side columns is the main reason of the greater degree of damage in them as compared with the middle columns.

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 The discrete element method (DEM), the finite element method (FEM) and the discontinuous deformation analysis (DDA) have been applied to earthquake response analysis of masonry retaining walls. However, some difficulties still remains for these methods and an alternative numerical method is required. In this study we applied the Smoothed Particle Hydrodynamics (SPH) to earthquake response analysis of masonry retaining walls by introducing a numerical model of rigid body. A series of shaking table tests were referred and the SPH simulations were conducted. The SPH simulation overestimated the displacement but reproduced the shape of residual deformation of masonry retaining wall after shaking.

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