Earthquake-induced slope stability has been evaluated by force-equilibrium of soil mass. But this method can't evaluate how large the deformation will develop and how far the effect reaches down-slope. The present study aims the development of evaluation method for residual displacement of slope during earthquakes by energy approach. We conducted an innovative model test on a shake table, in which energy balance in sliding slopes is measured. From these experimental results, a correlation between slope displacement and earthquake energy was obtained for variable input frequency indicating that the displacement can be uniquely correlated to the input energy the difference in input frequency.

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The paper reports a series of centrifuge model tests on uplift behavior of manhole in liquefiable deposit. A total of six cases of model tests are reported where density of the model deposit and intensity of input accelerations are varied. Measured excess pore water pressures around the manhole model are used for computing safety factor against the threshold level for uplift. The computed safety factor and the degree of measured uplift are not consistent with each other, implying that deformation analysis such as through finite element method may be important to evaluate the degree of uplift of manhole in liquefiable deposit.

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Methods are presented for application of the perfectly matched layer absorbing condition and the damping-solvent extraction method to dynamic response analyses of semi-infinite soil in time domain. Simple and Efficient displacement based finite element procedures have been developed for both methods. It is demonstrated by numerical examples that the performances of the developed procedures are better than the so-called viscous boundaries for both uniform and layered semi-infinite soil.

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[in Japanese]

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The Kizugawa Bridge on the East Osaka Route of Hanshin Expressway is 5 span continuous steel deck bridge whose interspace piers are rocking pier. Separated two bound girders are connected by lateral steel members. It is popular to adopt menshin seismic retrofitting for rather long bridges. But in this case, pear response displacement had to be controlled in allowable range because of allowable displacement of rocking pier. So special retrofitting methods such as integrated sliding bearing system and deviation protect device for pivot bearing on rocking pier are adopted. Additionally, lateral steel members connecting two girders are reinforced.

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The spectral attenuation character in high frequency range during the 1995 Hyogo-Ken Nanbu Earthquake is examined in order to propose a high-cut filter for strong ground motion prediction in this paper. It's cleared that the simulated spectra by the stochastic Green's function method are overestimated in high frequency range. The most suitable high-cut filter for two source models and four target sites is examined by comparing simulated spectra with observed ones. The obtained most suitable filter is very effective for strong ground motion prediction using the empirical Green's function method or stochastic Green's function method.

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[in Japanese]

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Dynamic centrifuge tests under 50 G and effective stress analyses (FLIP) were conducted to study the dynamic behavior of an embankment whose prototype height is 3 m. The embankment made of dry sand was constructed on the saturated sand layer whose relative density was adjusted to either 30% or 70%. Sinusoidal input motions with three different levels of peak acceleration amplitude were given. Objective of the study is to investigate the relationship between the magnitude of settlements and the peak amplitude of input acceleration.

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To precisely explain the influences of surface waves (Love wave and Rayleigh wave) on the ground vibrations, we have to demonstrate the relationships between body waves (P wave, SH wave and SV wave) and surface waves.
In this paper, three typical types of soil layers are considered.
1: One soil layer with infinite boundary
2: Two soil layers with infinite boundary
3: One soil layer with rigid boundary (Bottom of the soil layer is fixed)
By using the FEM complex Eigenvalue analyses proposed by J. Lysmer, the dispersion curves and eigenvectors of Love waves are demonstrated. The results of Rayleigh waves are also shown. Finally, the relationships between body waves and surface waves are clarified.

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In the seismic design of underground pipes, it is necessary to consider the influence of skin friction between structure surface and ground. Analyses of underground pipe models under influence of skin friction were conducted by Seismic coefficient method, to investigate the size effects. At the analyses, the diameters of structure models were 500mm, 1500mm, 3000mm, and 10000mm. JOINT elements were used for the models of skin friction between the structure model and the non-liner ground model. The results of the analyses, it was considered that the influence of interaction between pipes and ground, and size effects about t slipping and exfoliation behavior.

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This paper presents a series of fiber element analysis to reproduce experimental behavior of RC C-bent columns under cyclic and seismic excitations. In the fiber element analysis, the plastic hinge region of column was idealized by a fiber element to compute flexural hystereses. A torsional behavior is represented by a rotational spring, assuming that the torsional and the flexural hystereses are independent. The analysis provides a good numerical simulation in the longitudinal direction, while it does not correlate well in the longitudinal direction.

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When we have to regenerate the exact time behavior of underground pipes affected by seismic waves, it is important to make a precise model for the reciprocal action among slipping and exfoliation of them. However, it seems that a rational method for estimating the resistance of the circular section with a comparatively small diameter against earthquakes has not yet been established. Using parameter studies for sewer pipes with small diameters with changing the parameters such as coefficients of ground condition, sizes and underground depth of them under the existence of slipping and exfoliation, we tried to elucidate the size effect about the pipes affected by the shearing stress due to seismic waves. As the result, we obtained the knowledge about the size effect on the pipe enables us to exactly simulate the exact behavior of them.

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We prersent a method to evaluate input motions by mapping them to the feature space according to the response characteristics, adopting the Kullback-Leibler divergence as the norm. The proposed method makes it possible to evaluate input motions considering plural indices related to structural damage and also uncertainty of the input motion and structural parameters. Using the proposed method, the wavelet transform and Fourier transform are compared in terms of their performance as the input motion representation. Numerical computation results indicate the superiority of the wavelet representation.

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The damage was observed at many ground surface in 2004 Niigataken-Chuetsu Earthquake. In order to study the mechanism of ground response during earthquake, shaking table tests and effective stress analysis were conducted on the sand-silt deposit. We carried out shaking table tests on 4 type models. The analysis model used for this study was a strain space multiple mechanism model, which takes into account the effect of principal stress axis rotation. The recorded earthquake motion at a depth of 11.5 meters was used as the input earthquake motion for the analysis. The results of shaking table tests and effective stress analysis suggested that the decrease in shear resistance due to excess pore water pressure increase in the sand deposits increased the deformation of the ground surface.

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The effect of a seismic retrofitting method for rectangle underground structures is examined by analytical method. Seismic isolation material, expanded poly-styrol (EPS), and soil improvement are focused as seismic retrofitting methods. Effects of these material are studied in some ground conditions, in soft ground, hard ground, and soft ground contact with based rock just below the bottom slab. By studying each seismic isolation method in same condition, the applicability and character of them are made clear. The position of retrofitting materials and its property are changed widely in analysis for the future material development. Finally, the effect of some combination of retrofitting methods is also examined.

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[in Japanese]

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Many projects of the education for the earthquake disaster prevention have been carried out considering the experiences obtained through the 1995 Hyogoken Nanbu earthquake. However, such projects were not enough to educate the people over eighteen years old, because of their less motivation, for example. We, thus, developed web-based instructional materials as a tool to improve their comprehension of the earthquake disaster. The materials are designed for any people to study the topics about the earthquake and disaster for themselves. For the design of the materials, we paid attention to some points: they can study anytime and anywhere on the web and confirm their understanding through the review exercises. It is expected that the effective learning is advanced by these points. Some subjects tried to use the materials and their comprehension were evaluated by some exercises. From this, we verified quantitatively the effect of learning by means of the materials.

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In order to implement the proper design of structures in Damascus, the seismic behavior of soil and structure was examined numerically, and the seismic characteristics of both of them were determined. The study is carried out through two major steps; first, examining the seismic response of ground due to strong and weak earthquake motions; second, examining the soil-structure interaction due to the same motions. All seismic characteristics of both ground and structure will be determined from these analyses such as shear forces, displacements, bending moments, stresses ...etc. strong nonlinear properties were displayed, which proved the equivalent static method used in Syria insufficient.

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[in Japanese]

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Since the transfer function of an earthquake motion changes with the geometric conditions, in the case of embankments or grounds on inclined base layer, two or three-dimensional analysis is necessary.
In this research, a simple modeling method for seismic transfer function of ground on inclined base layer is proposed by superposing one-dimensional transfer functions on upper and lower sides of the slope. The weighting coefficients are determined by multiple linear regression analysis with the distance from the top of inclined basement and the length of the inclined basement as parameters.
It was confirmed that the transfer function obtained by the proposed method is consistent with the analytical result using the two-dimensional finite element method.

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The 1999 ChiChi-Taiwan and Kocaeli-Turkey earthquakes, did great damage to a number of bridges along the trace of the surface rupture. With fault motion and induced deformation on surface deposit, consequently an embedded foundation will be shifted from its original location, and deformed even though it is located off the major rupture zone. Understanding the important factors of soft surface deposit shearing is an essential step for investigating its effect on the adjacent structure. In this paper with considering nonlinearity nature of problem, a simple conceptual model is introduced, then essential dimensionless groups are extracted. Using Material Point Method (MPM) together with plasticity, the validity of derived groups are checked by 2D numerical case studies. The derived similarity law is useful for understanding the effect of factors like elastic, strength distribution among depth and deposit thickness. Then the effects of horizontal and vertical fault motion are separately studied and later with proposed framework the effect of material dilatancy, initial stress, Normal-Reverse type and dip fault motions are explained.

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The role of medical facilities after disasters is important. Especially, medical facilities themselves are under risks to be damaged by earthquakes, and it is essential to maintain safety of medical facilities. In consideration of safety of medical facilities from earthquake disasters, countermeasures to strengthen structure to earthquakes to avoid collapse of the buildings are not enough. It is necessary to consider the issues particular to medical facilities, that is, continuity of medical activities and safety of inpatients. In this study, issues of disaster management are discussed from the physical and non-physical perspective through the analysis of risk factors of buildings, facilities and system related to the continuity of medical facilities. Also activities of medical facilities from other areas are researched to analyze activities of disaster medicine from the holistic perspective.

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The supply to about 56, 800 households was stopped due to the earthquake. The gas pipe damage feature is that the main part had concentrated on the screw joint. Moreover, the case where the polyethylene pipe is damaged is not confirmed though about 25% of struck entrepreneur's low-pressure gas pipe was a polyethylene pipe. It was able to be confirmed that such a situation looked like the damage situation in the southern part of Hyogo Prefecture earthquake in 1995. The assistant outside the prefecture restored, and it took 2-4 week to the supply restart.

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[in Japanese]

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The objective of this study is to estimate the dynamic characteristics of subsurface ground in Minabe plains in Wakayama prefecture by micro-tremor observations. Minabe Plains has developed along the Minabe River, and is the second largest alluvial plain in Hidaka district. However, sufficient investigations about the dynamic property of subsurface ground have not been done. In this study, micro-tremor observations were carried out at 89 points in the plain, and the contour map of the predominant period of ground was presented. The contour map of the depth of engineering bedrock estimated with the data of borehole was also presented.

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Seismic safety evaluation of earth works on liquefiable ground currently uses Δu-method or seismic coefficient method to calculate the factor of safety. Recnetly, coupled effective stress dynamic analysis is gradually used to calculate the residual displacement induced by the earthquake including the possible liquefaction. This paper proposes to use seepage analysis, coupled effective stress dynamic analysis, and shear strength reduction technique to calculate the deformation and the factor of safety. We analyzed the Lower and Upper San Fernando Dam using the proposed approaches. The major slide for the Lower San Fernando Dam and the residual deformation for the Upper San Fernando dam was re-produced well.

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Because the influence of displacement induced by an active fault, especially an active surface fault on highway bridges has not been clarified, the countermeasures against the displacement by an active surface fault have not been applied in earnest in Japan. However, the investigation results on active faults have been open to the public in recent years in Japan. The construction projects will be not a little related to active faults in the near future. Therefore, it is very important to establish the practical procedures on countermeasures for highway bridges against the displacement by active faults.
In this study, the practical procedures are proposed based on the actual plan for a newly-constructed highway bridge at Beppu City in Oita Prefecture which is the first project considering the effects of an active fault in real earnest in Japan.

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An attenuation model incorporating the dependence of attenuation slope on earthquake focal depth for 5 % damped acceleration response spectra was determined by two-step regression analysis. The relations between source effects and earthquake types were investigated. Earthquakes were classified into four types (Type A-1: shallow inter-plate earthquakes, Type A-2: shallow intra-plate earthquakes, Type B: intermediate-depth earthquakes, and Type C: inland crustal earthquakes). Variation in source effects according to earthquake types is large in shorter-period rang and incorporated into the attenuation model.

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Nowadays the seismicl intensity scale has become an important information for real time counter-measures soon after disastrous earthquakes. However, some investigations of damage due to recent earthquakes such as the 2003 Miygiken Hokubu Earthquake revealed problems over how and where to set an instrument for measuring seismic intensity. Especially, the difference in seismic intensity between at the ground surface and in buildings has focused. This paper deals with the variations of seismic intensity using records due to an array observation system for ground and building motions. The array observation system, which was installed at the campus of Tohoku Inst. of Tech. 15 years ago, has obtained some 90 motion records simultaneously at different sites of the free ground surface, the first floor and fourth floor of a 4-story building.
The instrumental intensity scales were obtained from the records to compare their values at the different sites. The results made it statisyically clear that the instensity at the firast floor is smaller by 0.2 than the one at the ground surface. This difference was also found in array observation of microtremors, leading to a conlusive remark so that microtremors are available to predict a difference of seismic intensity depending on installation sites.

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Liquefaction of sandy soils causes not only uniform settlement but also differential settlement of spread foundations. During the 2000 Tottoriken-seibu earthquake, differential settlements of many houses occurred at Abehikona housing development in Yonago City. According to measured inclination of the houses, there was a tendency that tow adjacent houses tilt towards the inside of the houses. The authors conducted several shaking table tests on model houses to demonstrate the direction of the inclination of adjacent two houses. Test results also showed that the two adjacent houses tilted towards the inside of the houses.

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In this paper, for early earthquake damage assessment systems, the earthquake building damage estimation method is developed, using one of the seismic design methods of structures, the capacity spectrum method. This calculation method is simpler than the time history response analysis and the spectral characteristics of seismic ground motion and the natural period of a building can be considered because the response spectrum is used as an input ground motion. And the seismic performance of buildings is identified by using the building damage survey data from the 1995 Hyogoken-Nanbu earthquake and Niigataken-Chuetsu earthquake.

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A lot of liquefaction counter measure methods have been developed, which are methods improved the wide-ranging ground. In railway structures, which are line structures, it is not reasonable to apply those methods. In this paper, we propose a method improving limited to subgrade around pile foundation using chemical grouting method or deep mixing stabilization method. We confirmed the validity of the proposed method by model shaking tests.

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It was the first time for Shinkansen trains on business to derail at the time of the 2004 Niigataken-Chustsu Earthquake. Because various prior measures were effective and it was fortunately, the derailment caused no disaster. One of the countermeasures against earthquake disaster for Shinkansen, the early earthquake detection system has been installed to reduce the level of the disaster as possible. At the time of this earthquake, Compact UrEDAS for Joetsu Shinkansen make alarm one second after P wave detection at the epicentral area, and all trains around epicenter were urgent stopped. Although it was less than three seconds for the derailed train from the alarm to severe earthquake motion begins, the alarm decreased the possibility to run the possible damaged area more than 130m and to rush of the opposite train in the derailed area. Compact UrEDAS demonstrated that it is effective enough even for the earthquake just below as concerned. Moreover from the analysis of the derailment situation, main portion of derailment was caused by the large relative displacement between the specific viaducts. It was assumed that high frictional heat was caused by the derailed vehicle bodies slid on the rail after the earthquake as body landing, and the transformation and breaking the rail occurred just after the train running.

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[in Japanese]

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Ground liquefaction caused in nearby underground structures may create potentials of soil uplifting. In our research, by employing scaled model of Box Culvert sized in width of 5.85m by height of 3.15m, uplifting performance of the underground structure and the effects of the liquefaction countermeasure using sheet pile were examined. The testing was conducted using centrifuge model test field with 25G for non-countermeasure model and countermeasure model with sheet piles. The testing model was created with rigid PVC and its specific gravity was set as 0.75. As a result, the experiments provided data on uplifting performance of the underground structure and effects of the countermeasure methods to reduce soil lifting. Furthermore, the results of the each test were applied to estimation formula of soil uplifting rate, and then the estimated value and the observed value were compared.

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[in Japanese]

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In the present study, in order to express the normal pressure and sliding velocity dependency of frictional force, the numerical model was developed based on the tribology theory and the property of materials. This model could show the good agreement with the experimental results in the stationary vibration state, but it is impossible to present the decrease of the friction coefficient just after the beginning of frictional motion. Taking account with the temperature characteristics, the proposed model is revised. Since it is very difficult to measure the temperature at the real contact area, the hysteresis energy of the isolator is used instead of the temperature. Compared with the experimental results, it is found that the numerical model can simulate well the behavior of frictional isolators under variational normal pressure, sliding velocity and temperature.

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[in Japanese]

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[in Japanese]

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Studied herein is an experimental study on the collision between two steel girders using shock absorbing rubber, in order to investigate the influence of mass of girders on the reduction of impact force. The mass of girders ranges from 250kg to 500kg on 3 stages. As a result, it is found the impact forces are not different even if the mass is turned over between collision girders. Consequently, it is clarified the impact force is correlation with the total mass of girders not the mass ratio.

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[in Japanese]

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Uplifting phenomena of underground tube structures was analyzed by FEM liquefaction code. Uplifting initiates as the excess porewater ratio of surrounding soil layers exceeds over 0.8. Uplifting continues constantly although the fluctuation of surrounding excess pore water pressure or amplitude of vibration.
The soil improvement method and the earth nailing method as countermeasures for uplifting were investigated using same FEM code. It was found that the countermeasures treated underneath of the tube is more effective than that at the head of the tube.

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A soil database of the damaged area by The Mid Niigata prefecture Earthquake in 2004 was established based on collected 746 boring data.
The distribution of amplification factor was computed by using soil properties of the boring data.
In order to investigate the relationship of the strong ground motion and the pipeline damage, the distribution of surface strong motion was evaluated from the observation records taking account of amplification factors of shallow soil deposits.

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[in Japanese]

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The paper deals with the H/V spectral ratio of the P-wave motions to empirically derive the amplification factors due to the local soil conditions. The Sendai Observation Site of KiK-net was discussed as a trail site for the purpose. The WV spectral ratio obtained from the records at the site shows a good correlation with the theoretical amplification factors. This paper concludes that the P-wave phases of strong ground motions provide effective information of amplifications due to local soil conditions by use of the H/V spectral technique.

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[in Japanese]

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It is in fact difficult to construct all bridges so as not to cross the inland active fault because a lot of inland active faults exist in Japan. In this study, the relation between fault displacement in the direction of the bridge axis and the damage of the bridge has been examined using static analysis with displacement control method for the PC rigid frame bridge with center span of 100m. Here, two cases have been assumed for the boundary conditions of analytical model of the PC rigid frame bridge, one is with the spread foundation being fixed, the other is to consider the nonlinear behavior between the spread foundation and soil. By the analytical results of these two cases, comparative study has been carried out about the influence of the foundation size on the damage of the bridge caused by fault displacement.

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A GIS-based 7.5-arc-second Japan Engineering Geomorphologic Classification Map (7.5-arc-second JEGM) was developed for Niigata region where the Niigata-ken Chuetsu earthquake of October 23, 2004 attacked. The map contains the attributes of geomorphology in grid cells that are 7.5 arc-seconds in latitude x 11.25 arc-seconds in longitude (approximately 250 x 250 m) in size. In this paper, liquefaction hazard zonation for the 2004 Niigata-ken Chuetsu earthquake was performed using the 7.5-arc-second JEGM. The mapping proved to be generally consistent with field experience during the earthquake.

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The Niigataken tyuetu earthquake of magnitude 6.8 occurred on October 23, 2004, and the cause was considered. The relation between the excellence cycle of the ground compared with H/V and the thickness of the layer of the subsurface layer was clarified. It has been understood that the excellence of the alluvium corresponds to the second peak compared with H/V. Moreover, making the ground nonlinear was admitted from the seismic response analysis in the offing product terrace layer.

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A damage of embankment due to liquefaction represents its settlement on the liquefied ground. From the point of view of the safety railway service, it is important for selecting a countermeasure against liquefaction to evaluate the ground deformation during and after liquefaction. To have a better insight into the function of a rational countermeasure against liquefaction, a series of shaking table tests was performed. The research reported here focuses specifically on the evaluation of relationships between the settlement of embankment and the degree of liquefaction.

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