In this study, the effects of the characteristics of pulse-like seismic motion observed near faults on the permanent displacement of slope shoulders were investigated using two-dimensional elasto-plastic finite element analysis. Ricker wavelet was used as a model wave to characterize the pulse-like seismic motion for directivity pulses, and a sine wave of one cycle was used for fling steps, and these were input as horizontal acceleration on the slope. The effects of the direction of action of Ricker wavelet and sine wave of one cycle on the permanent displacement of the slope shoulder were compared by aligning the maximum amplitude. The results showed that the maximum value was obtained when a sine wave with one cycle was input so that the inertial force acted laterally towards the lower ground in the latter half of the cycle. In addition, the effect of the direction of input on the permanent displacement of the slope shoulder was greater when the pulse frequency was low for the Ricker wavelet and high for the sine wave with one cycle.

 In this paper, surface ruptures caused by the 2024 Noto Peninsula earthquake were discussed mechanistically based on the stress changes in the surface rock mass due to crustal deformation. The possibility of rupture of the surface rock mass was evaluated using the local safety factor, which is defined as the ratio of the shear strength to the shear stress, calculated by the elastic theory of dislocations. The results suggest that the surface ruptures near the Wakayama River in Suzu City are located in a region where the local safety factor is less than 1, and are secondary faults. On the other hand, the surface rupture observed near the Togigawa-Nangan fault has a local safety factor greater than 5, suggesting that it is not a secondary fault.

 In this study, 3D dynamic effective stress analyses were conducted to reproduce the experimental results of a 1G field shaking table test subjected to biaxial horizontal seismic motion on saturated sandy ground. The 3D dynamic effective stress analysis used a model that accounts for the dissipation of excess pore water pressure. Three types of biaxial horizontal seismic motions with the same biaxial acceleration response spectra were input: one one-directional motion and two biaxial motions with different acceleration trajectories. Based on the analytical results, the build-up and dissipation processes of excess pore water pressure were consistent with the experimental results. Additionally, even in analyses using a model that does not consider the dissipation of excess pore water pressure, the increase process of excess pore water pressure was accurately reproduced. The increase of excess pore water pressure was greater under the biaxial horizontal seismic motions than under the one-directional seismic motion. This demonstrates the validity of the constitutive model used.

 In rock anchors used to stabilize rock slopes, tensile failure can occur at the anchor’s fixed end during strong seismic events. To investigate the effect of this tensile failure on the mechanical properties of the anchors, we conducted anchor pull-out tests and centrifugal loading model experiments on anchor models that simulated the presence or absence of cracks. The rock mass was modeled and created by combining blocks of artificial soft rock, assuming that the boundaries between the blocks represented failure surfaces caused by tension. The results of the anchor pull-out tests indicated that the decrease in anchor force was mitigated by the effect of confining pressure and the interlocking of cracks. Furthermore, based on the results of anchor loads and various displacements measured in the centrifugal loading model experiments, we analyzed the relationship between anchor load and displacement and examined the dynamic mechanical properties of the anchor with and without cracks. Within the range that does not exceed the ultimate anchor force, no significant difference in dynamic deformation characteristics was observed due to the presence or absence of cracks.

 When bridge abutments are constructed on soft ground, EPS embankments are installed behind the abutments as a countermeasure against soft ground. In this study, a full-scale bridge with EPS embankment applied to the back of a rigid-frame abutment was modeled and its seismic behavior was verified analytically. The bridge was modeled in accordance with the specifications for highway bridges, using the same procedure as in actual design. As a result, it was confirmed that the application of EPS embankment to the back of the rigid-frame abutment causes more significant seismic earth pressure than the normal backfill soil at the location of the reinforced concrete slab, similar to the results of previous studies of inverted-T abutments. It was confirmed that the seismic earth pressure at the location where the concrete slab was installed could be reduced by replacing a part of the concrete slab with EPS blocks.

 Recently, caisson foundations have been increasingly used as bridge foundations in narrow areas, etc., as improvements in construction technology have made it possible to deepen the rooting in small sections. In this study, horizontal loading tests were carried out in aluminium bar laminates using a caisson foundation model with the parameters of rooting ratio and dead load safety factor (ratio of ultimate bearing capacity to vertical dead load), focusing on the cumulative behaviour and mechanical properties of caisson foundations with rooting after an earthquake. The results showed that the ultimate bearing capacity at the bottom of the caisson foundation with rooting was over-estimated in relation to the maximum ground reaction force at the bottom of the caisson foundation measured during the experiments, which may lead to residual displacement. This paper proposes a method for calculating the limit bearing capacity of the caisson foundation bottom taking into account the dead load safety factor and rooting ratio, as well as the limit values of the foundation bottom reaction moment to avoid the occurrence of harmful residual settlement.

 In this paper, the applicability of numerical simulation is verified by analyzing the behavior of a centrifuge model of a circular shaft in a dense sandy soil with the upper layer dry and the lower layer saturated. In addition, the numerical model was used to analyze the effect of the width of the sand layer on the seismic response of the circular shaft, taking into account the various conditions of the actual circular shaft (shaft stiffness, relative density of the sand layer, drainage conditions).

 The results showed that it is possible to evaluate the response of the ground and circular shafts by appropriately setting the physical properties of the sand ground and circular shafts. In addition, it was also found that if the width of the sand ground is secured to be at least as wide as the diameter of the circular shaft, it is possible to appropriately evaluate the response of the circular shaft when the stiffness of the circular shaft is large, such as before the concrete cracks. However, when the circular shaft has low stiffness, as in the case of concrete cracking, the response of the circular shaft was overestimated in the model with a narrow sand layer depth.

 In the seismic design of underground structures such as cut and cover tunnel, the interaction between the structure and the ground must be properly evaluated. The interaction depends on the ratio of the shear stiffness G_s of the tunnel box structure to the shear stiffness G_g of the ground (hereinafter referred to as the stiffness ratio G_s/G_g). A model experiment was conducted in which a box model with arbitrarily set stiffness was embedded in a shear tank that caused static shear deformation of the ground using aluminum bar-laminated soil. As a result, it was confirmed that the interaction force acting on the box was reduced compared to the previous findings obtained by equivalent linear modeling of the ground and without considering the sliding behaviour. A method was proposed to introduce a correction factor to account for this reduction, and it was confirmed that the experimental results of the strain transfer characteristics could be evaluated appropriately.

 The authors investigated a method of connecting additional piles using friction materials (referred to as friction-jointed piles) to enhance rigidity and damping functions through 1/20 scale model experiments in a 1G field. Friction-jointed piles incorporate frictional joint surfaces on both sides of the footing, where compressive force is applied. In this study, numerical analysis was conducted to examine the behavior of the proposed friction-jointed piles at actual structure scale, accounting for member nonlinearity. Even at full scale, the friction-jointed pile method effectively reduced peak response acceleration while maintaining the predominant vibration period near the optimal introduced friction force, compared to conventional pile reinforcement. In cases where structural damage occurred, although response values increased due to initial rigidity, the frictional energy dissipation in the friction-jointed spring helped reduce damage to the structure compared to standard pile reinforcement methods.

 In this study, we evaluated the residual strength of Kanazawa Port Gokuden No. 1 Wharf (-10m), a sheet pile quay wall damaged by the 2024 Noto Peninsula earthquake, toward its temporary operation after the disaster. First, we organized the damage situation of the wharf based on on-site reconnaissance and survey results. Next, we carried out two different types of analyses, namely, a 2D frame structure analysis and a time-history finite element analysis for the soil-structure system using a program called FLIP to reproduce the damage situation to evaluate the residual strength of the steel members after the disaster and the current stability. This is the first case in history in which a time-history finite element analysis was used for the evaluation of the residual strength of a damaged port structure for temporary operation. The results clearly indicated that the time-history finite element analysis is advantageous in a sense that it can consider the residual displacement of the ground, leading to a more realistic evaluation of the stress status of steel members. This case study tells us that, to improve our preparedness to earthquakes, it is recommended to apply FLIP analyses to important sheet-pile quay walls and pile-supported wharves to establish relationships between the residual displacement and the stress status of the members.

 The applicability of numerical analyses of liquefied ground responses is generally verified by comparing them with limited measured values such as acceleration and excess pore water pressure in centrifuge loading test. However, the coincidence of some time histories, such as accelerations and pore pressures of specific points, may not be sufficient to validate the full confidence of the calculated results of this numerical analysis, and then the further validations are expected to consider the dominant mechanisms of the phenomenon. To realize such validations, the evaluation of the shear stress in the soil plays an important role. Therefore, in this paper, two earth pressure gauges were installed at ±45° from the horizontal plane in a centrifuge loading test to evaluate the shear stress of the soil. Furthermore, the results were compared and verified with a 2D effective stress analysis. As a result, it was confirmed that the shear stress can be estimated using two earth pressure gauges even in dense ground where an RC circular shaft and embankment are present. It was also confirmed that estimating the ground shear stress using two earth pressure gauges makes it possible to verify numerical analysis based on the ground shear stress.

 The effect of the reinforcement method was analytically investigated through a seismic response analysis of embankments, considering slope failure using the particle-element coupled method (PEM). In PEM, the embankment is modeled as a gathering of particles, and the reinforcement structures are modeled as elements. PEM was initially applied to the seismic response analysis of embankments involving slope failure which were performed in a centrifuge to confirm the reproducibility of the method using three-dimensional model. Next, a series of numerical simulations were conducted using a reproducible numerical model, focusing on the arrangement of the ground with nailing reinforcement and along with the frame reinforcement method. The results showed that settlement only occurred on the top of the embankment when the nailing was densely placed. Settlement and tilting occurred when the nailing was insufficient, whereas settlement, tilting, and gap occurred when there was no reinforcement or insufficient rooting without any reinforcement effect. The frame reinforcement was analytically shown to be more effective with the nailing in restraining displacement in/after earthquakes even when the nailing was placed sparsely. The results of this study on the reinforcement arrangements demonstrate the importance of estimating the range of slope collapse in advance in the absence of reinforcement, to enable reinforcement construction with an appropriate rooting length and placement density.

 The authors are conducting centrifuge loading tests and replicated analyses to develop a seismic performance verification method for RC circular shafts constructed in dense sand and gravel ground. In the centrifuge loading tests, three waves of excitation were continuously applied, whereas the applicability of the analysis has been studied by using each excitation wave as a single input in the replicated analysis. In this study, we performed a replicated analysis with continuous input as in the experiment and confirmed that the effect of the continuous input was slight and that a single input was sufficient. In addition, the ground and structure responses due to differences in the modeling of saturated ground were examined, and it was confirmed that when the seismic performance of a structure is verified, the ground should be modeled in such a way that the evaluation of the structure is conservative.

 Recently, a number of railway embankments have been damaged due to heavy rainfall in Japan. Large soil-bags are often utilized for the emergency recovery. When carrying out the full recovery of the embankment, the large soil-bags are usually removed beforehand, which causes inefficiency. In the literature, a full recovery method without removing large soil-bags has been proposed. However, they assume reinforcing the embankments behind the soil-bags, and do not consider the simple constitution where the emergency recovered embankments is covered by additional soils without reinforcement behind the soil-bags. In this study, model shaking table tests are conducted to understand the failure mechanisms of the fully recovered railway embankments using large soil-bags covered by additional soils. From the experiments with the emergency recovered embankment, rotational vibration of the large soil-bag as a rigid body is developed in the lower confining stress region, and extrusion of the large soil-bags and settlement of the embankment top is observed. From the experiments with the fully recovered embankment, the vibration of the large soil-bags and deformation of the covering soils is observed near the top. It is considered that the fully recovered embankment has still insufficient seismic resistance compared to the embankment before the disaster, and measurements are necessary to minimize the relative motion of the large soil-bags to the soils.

 Noto Peninsula Earthquake that occurred at 16:10 on January 1, 2024 caused extensive damage to the quays of the Port of Nanao. Although the No. 2 quay in the Ota area (Section B: a sheet pile quay wall with vertical anchor pile, Section C: a sheet pile quay wall with a group of anchor piles ) and the cargo quay (a sheet pile quay wall with vertical anchor pile) in the same area were constructed at about the same time and have the same quay structure that is sheet pile quay wall, there were significant differences in their behavior during the earthquake. Therefore, the damage to the quaywalls was verified by field survey, and the factors causing the difference in seismic behavior were examined, focusing on the countermeasures against liquefaction, anchor type structural differences and soil characteristics. Next, a two-dimensional seismic response analysis was conducted using the earthquake motion simulation of the Noto Peninsula earthquake, and it was shown that the behavior and deformation of both quay walls due to the earthquake can be reproduced by setting proper parameters. Furthermore, this study shows a method for estimating the bending moment of the sheet pile based on the results of the detailed investigation by diving, and this study evaluated the soundness of the sheet piles based on the results of this estimation method. Finally, there were generally similar results by comparing the bending moment between the estimation method and the reproduction analysis, and the validity of the soundness evaluation was verified.

 This study investigates the application of log piles as a shallow ground improvement technique against liquefaction for low-rise buildings. This method has recently gained attention for its potential to sequester carbon and mitigate climate change. The research conducted 1G shaking table experiments and needle penetration tests to evaluate the method’s effectiveness. The primary objective was to clarify the impact of pile length on the effectiveness of liquefaction countermeasures by varying the improvement depth while maintaining a consistent thickness of the liquefiable layer. The key findings from the experiments revealed several significant outcomes. Firstly, the penetration of piles resulted in densification in both the vertical and lateral directions of the surrounding soil. Secondly, even with shorter pile lengths, the liquefaction-induced settlement of the structure model was notably reduced compared to non-improved ground conditions. Furthermore, depending on the pile length, lateral ground displacement was suppressed, which contributed to a further reduction in settlement.

 With the increase in the base earthquake ground motions after the 2011 off the Pacific coast of Tohoku earthquake, it has become necessary to upgrade the conventional conservative evaluation of seismic safety. In particular, there is concern that seismic performance verification may become more difficult when critical civil engineering structures such as tunnels, culverts, etc., intersect with crush zones. In addition, the behavior of RC structures affected by local deformation due to crush zones is still largely unknown, and an evaluation method needs to be developed. Based on the above background, we conducted a series of practical seismic safety evaluations for a hypothetical full-scale tunnel structure that intersects a crush zone located in bedrock. Specifically, we conducted a dynamic ground response analysis to calculate the response deviation of the fracture zone and a static RC nonlinear analysis to calculate the limit deviation, separately. In the calculation of the critical displacement, the maximum load point was evaluated as the critical state, and it was confirmed that the same evaluation could be performed using damage indices such as compressive strain and level difference. Furthermore, the seismic performance was verified by comparing the results of the two analyses with consideration of the factor of safety.

 The Noto Peninsula earthquake that occurred on New Year’s Day, 2024, caused various kinds of damage. In particular, liquefaction and tsunami disasters in coastal areas are important issues, but they are discussed separately, and there is little awareness of the fact that they are phenomena that occur in succession. In this paper, we present the characteristics of past earthquakes, investigate liquefaction damage in the Noto Peninsula earthquake, present the results of interviews regarding roadblocks to evacuation on sand boil, and conduct experiments on road movement covered by sand fountains, which may be an obstacle during tsunami evacuation, to understand the reduction in evacuation speed. The results also showed that the speed of evacuation was reduced by the movement of the road covered by the sand boil.

 In this paper, a fundamental study focusing on the effects of damping of ground and structure was conducted to improve the combination of ground deformation and inertia force when using the seismic deformation method. Specifically, dynamic analyses were conducted for various types of grounds and structures, varying the damping of one or the other, and the combination coefficients of the actions were compiled and discussed. As a result, it is clarified that the combination coefficients of the action change with the damping of the ground and the structure. The tendency of this change is formulated, and a simple formula is proposed to calculate the combination coefficient of the action, taking into account the effect of damping. Using the proposed method, it is possible to set more appropriate combination coefficients than before, taking into account the effects of damping of the ground and structure.

 RC tunnels intersecting crush zones are subject to local deformation due to shear displacement during earthquakes. The authors have conducted analyses to reproduce model tests of RC tunnels intersecting crush zones and have confirmed that the load-bearing capacity and deformation performance can be reproduced with high accuracy. In this study, nonlinear analysis using a discrete rebar model was conducted to analyze the effects of rebar size and spacing. In the comparative analysis for a small experiment RC model, no significant differences were found in the results. On the other hand, in the case of a full-scale tunnel, although the differences were not large for standard rebar size and placement, the maximum load and the displacement relative to the maximum load were reduced to approximately 60-70% with extreme rebar design, indicating that the failure mode may change in the analysis.

 In this study, element tests comprising monotonic and cyclic shear tests were conducted on volcanic ash coarse-grained soil, which is susceptible to particle breakage under external forces, to identify the stages during shearing at which particle breakage occurs. The soil samples were prepared with a particle size range of 2.00–0.85 mm to facilitate the quantification of particle breakage during shearing. The results from the monotonic shear test indicated that particle breakage did not occur at the point of maximum shear stress but was initiated when the effective stress path reached the failure line (FL). In the cyclic shear tests, pronounced particle breakage was observed under cyclic mobility conditions, where the effective stress path repeatedly approached zero effective stress and then recovered along the failure line (FL). These findings revealed that, in both shear test methods, particle breakage occurred after the effective stress path intersected the failure line (FL).

 The use of response spectra is an effective engineering technique to account for the periodic characteristics of seismic ground motions. With the progress of research on the characteristics of seismic ground motions, ground motion models have been developed into more complex functions. On the other hand, non-parametric ground motion models, such as machine learning, have been proposed. The advantage of non-parametric models is that it is not necessary to consider the functional form in advance. This study quantitatively investigated the applicability of Gaussian process regression, one of the non-parametric methods, to acceleration response spectra. Gaussian process regression has the problem of steeply increasing computational cost as the amount of learning data increases. Therefore, by applying the sparse approximation to large amounts of learning data, good results were obtained while reducing the computational cost. In order to obtain the best possible ground motion model, several issues in the Gaussian process regression were investigated.

 A study was conducted to understand the effect of engineering bedrock on the predominant period of surface layer. The results confirmed that even when the natural period T_g derived from eigenvalue analysis is the same, the interaction with engineering bedrock can cause significant changes in the predominant period and ground motion. Additionally, it was clarified that when the natural periods of the first and second modes from eigenvalue analysis are relatively close or when the shear stiffness of the surface layer is relatively large, the influence of engineering bedrock is likely to shorten the predominant period compared to T_g. We proposed a method to easily correct this tendency and confirmed that the proposed method can more appropriately estimate the dominant period of the ground. By using the insights obtained in this study, it is expected to improve the accuracy of estimating the predominant period of ground during earthquakes

 In this study, we propose a method to efficiently calculate ground motions for inland crustal earthquakes using a database of waveforms at seismic bedrock calculated by assuming various source and path characteristics using the statistical Green’s function and by considering empirical site amplifications at each location. We confirmed that the surface ground motions calculated by the proposed method can reproduce the observation records as accurately as the recent GMM in terms of the response spectra. The residuals between the proposed method and earthquake records were calculated. The proposed method was able to evaluate the residuals with less variation than recent GMM by taking into account empirical site amplifications of the sites.

 Seismic ground strain is used in seismic calculations for buried pipes, but even with high-density observation of seismic ground motion, there are limits to the ground strain that can be observed. In this study, we focused on distributed acoustic sensing (DAS), which can measure strain rate at intervals of several meters using existing optical fiber cables laid along roads. Using DAS measurements and simultaneous observations from multiple seismometers along National Route 9 in Kyoto Prefecture, we clarified the characteristics of the strain measured by DAS during earthquakes. As a result, it was possible to confirm continuous and dense vibration of the optical fiber cable on all lines during near-field earthquakes of magnitude 3 to 4, and the propagation of P-waves and S-waves were clear. Furthermore, in the DAS measurement channels with strong signals, it was confirmed that the frequency characteristics of the strain measured by DAS reproduced the frequency characteristics of the strain measured by the seismometer well.

 We propose a method to modify the JMA measured seismic intensity to correspond to the actual earthquake damage, aiming to rapidly estimate the global intensity measure such as Modified Mercalli Intensity (MMI) from seismic records like the JMA seismic intensity. The rigid-plastic response is obtained from the seismic records and input into the existing procedure for calculating measured seismic intensity. Compared with the MMI obtained from the damage of the 2023 Kahramanmaraş earthquake in Turkey, the proposed method shows a good correlation. The best model parameter was obtained when the yield seismic coefficient of the rigid-plastic model was set to 0.4. In actual application in Japan and other regions in the world, it is necessary to select an appropriate yield seismic coefficient according to the buildings and structure types in the areas.

 It is important for government agencies to quickly assess the damage after an earthquake and to take appropriate emergency actions. Currently, estimates of the spatial distribution of seismic intensity are released immediately after the occurrence of an earthquake, however the key issue is that they underestimate the seismic intensity near the earthquake source fault, which is considered to be larger than that recorded by seismic stations. In this study, to solve the underestimation of seismic intensity near the earthquake source fault, spatial interpolation of ground motion was performed using Physics-Informed Neural Networks (PINNs). The model was trained on a two-dimensional SH wave field using the prediction error of ground motion at assumed station locations, the error obtained from the two-dimensional wave equation, and the stress condition on the ground. The analysis results showed that the model was able to predict values larger than the maximum values recorded by the stations, confirming improved prediction accuracy in the vicinity of the earthquake source. In addition, the method was found to be effective in predicting ground motion before they reach the stations. This method is expected to contribute to the rapid identification of earthquake damage and its response.

 A basic study on a seismic response analysis of large-scale structures such as nuclear power plant buildings considering seismic uplift was conducted to improve the quality of seismic response analysis by high-fidelity finite element model and to pursue the rationality of the model. In addition to the usual finite element model in which the ground and the structure are combined, another model with reduced degrees of freedom was proposed by considering the contact condition between the ground and the structure. The results obtained from the analysis suggest that the high-fidelity finite element model may be able to consider the effects of foundation deformation and building geometry when considering the uplift of large-scale structures. In addition, it was shown that reducing the number of degrees of freedom by considering the contact condition is superior in terms of computational cost and can be used as a reasonable model in future seismic response analysis.

 We analyzed the strong ground motions during the Noto Peninsula earthquake using duration spectra representing three essential factors of amplitude, period and duration. Using horizontal two components of accelerograms recorded in Noto area, we evaluated the spectra representing the uniform duration of velocity response envelope exceeding various levels of threshold. Comparing them with JR Takatori station during the 1995 Hyogo-ken Nanbu earthquake, we found that durations in the period range of 1-3 s at JMA Fugeshi and other stations exceed those at JR Takatori. Next, we discussed the ratios of energy spectra to velocity response spectra as the effect of long duration based on the random vibration theory. We also evaluated the directionality of energy spectra that account for concentration of energy input along the predominant direction.

 There are few research about overlapping phenomenon of earthquakes and tsunamis. As a progress report, this study aims to calculate the behavior of a structure and fluid when an earthquake acts by applying the fluid-rigid-body interaction analysis method.

 The results confirmed the following: (1) the force acting on the breakwater calculated by this analysis method is approximately the same as the design value. (2) dynamic water pressure becomes slightly smaller when the structure moves. (3) it is possible to evaluate the structural stability during an earthquake. (4) compared with FEM analysis (program code: FLIP ROSE), although there are some differences in the results of displacement due to the influence of the parapet, but it is confirmed that the similar earthquake response analysis regardless of the analysis method and time.

 Bulging is a coupled vibration between tank wall and content fluid. This phenomena is induced by seismic ground motion. In general, water tanks are divided into two parts by partition plates. There is a case of water leakage due to damage to partition plates caused by the bulging. In this study, to clarify the mechanism of bulging in the partition plate and analyze its effects, vibration experiments and finite element analysis are conducted on an acrylic rectangular model tank with a two-compartment structure. First, the natural frequencies of the side walls and partition plate are estimated based on the results of vibration experiments and eigenvalue analysis. Subsequently, a time-history response analysis is conducted utilising the aforementioned natural frequencies, thereby corroborating the reproducibility of the vibration experiment results. This enables the replication and characterisation of bulging in the partition plate. Finally, water pressure acting on the side walls and partition plate is calculated from the time history response analysis results, and the pressure distributions are compared. As a result, it is found that the current design guidelines may not hold during resonance with the partition plate.

 Although earthquake damage to bridges has been decreasing, countermeasures against multi-hazards, such as tsunamis after earthquakes and flood damage before and after earthquakes, are insufficient. In recent years, many bridges have been washed away or destroyed by floods in Japan. This study conducted numerical analyses of several types of flows to investigate the effect of using inspection platform as fairing for maintenance of bridges. By comparing the results with the bearing capacity specified in the seismic design specification for highway bridges, the conditions necessary to prevent girder washout in the event of flood damage are discussed. The results show that covering the lower half of the girder with a fairing, even if the fairing does not cover the entire girder, can reduce the hydrodynamic forces.

 In this study, we focused on the high deformation performance of polyethylene pipes and evaluated the seismic performance of a gas pipeline network that includes PE pipes. Specifically, we divided the network into grids, and used the proportion of PE pipes buried in the grid as an explanatory variable to examine its relationship with the damage rate of screwed joints. As a result, it was confirmed that as the proportion of PE pipes buried increased, the earthquake resistance of the network improved and the damage rate of screwed joints decreased. Furthermore, we modeled a pipe containing a mixture of PE pipes, performed numerical analysis, and quantitatively confirmed its effectiveness from a mechanical perspective.

 When a large-scale disaster strikes, the burden on the local governments affected by the disaster (hereinafter referred to as “recipient local governments”) increases dramatically, as they are required to manage evacuation centers and transport supplies in addition to their normal duties. However, as they return to their original location at the end of their deployment period, they often do not accumulate sufficient local support expertise. If the problems and solutions faced by relief workers in the immediate aftermath of a disaster during their deployment could be systematised, and if other relief workers could benefit from this knowledge, it would be possible to more effectively support the decision-making of the host community in the event of a possible future disaster. In this study, we applied qualitative data analysis methods to the results of interviews conducted by the Japan Society for Community Safety after the Noto Peninsula Earthquake of 2024, and attempted to structure the difficulties faced by dispatched staff and the knowledge they needed to overcome these difficulties.

 In the 2024 Noto Peninsula earthquake and other earthquakes of seismic intensity 5 or higher, sloshing and bulging have been identified as the primary causes of damage to water storage tanks. In particular, sloshing damage is frequently observed in the upper walls and ceilings of water storage tanks. In order to elucidate the characteristics of sloshing, a model of a double-tank structure was constructed, wherein the interior of the vessel was partitioned into double sections by a partition plate. The results demonstrated that the wave height and hydrodynamic pressure reached their maximum values at a vibration direction angle of 45°. The findings indicate that the sloshing phenomenon differs from the assumptions made in existing design guidelines and highlight the necessity for further investigation into sloshing at an excitation angle of 45°.

 Damage to stainless steel panel water distribution tanks has been reported in recent earthquakes. The guidelines for the seismic design of water supply facilities have been updated to include an examination of the seismic resistance of water tanks in terms of bulging. In the 2024 Noto Peninsula earthquake, stainless steel panel water tanks that had also been damaged in the 2007 Noto Peninsula earthquake were again at the exact location. Since many of the strong seismic motions observed were predominant in the periods of 1s or more, the effects of long-period responses due to sloshing (liquid surface oscillation) and short-period responses are considered. In this study, we conducted a shaking table experiment using a model water tank, assuming a rectangular water tank, and examined the dynamic water pressure on the side walls due to short-period waves, long-period waves, and observed waves, as well as visualizing the water flow. As a result, it was found that sloshing vibrations contributed to the side wall water pressure when the observed waves were used for excitation.

 In this study, we quantify uncertainty and include it appropriately into tsunami scenarios for inundation analyses for nuclear power plants. The uncertainty in responses of tsunami analysis is affected by dominant factors involved in fault characterization and rupture distribution, relative to tsunami source and evaluation point, submarine topography and site-specific geometry in land, so it is worthy importance to classify and quantify the uncertainty in site-specific tsunami inundation analysis. Feature values representing uncertainties in tsunami analysis were defined and the influence analyses on tsunami height at shoreline using machine learning were implemented, for tsunamis along the Japan Trench. Features related spread of wavefield in a north-south direction and maximum initial water level were highly influenced to tsunami height at shoreline, in case of tsunamis along the Japan Trench. The results also showed the importance and validity of relative position to tsunami source and evaluation point when considering the multiple evaluation points are considered.

 In this study, we aimed to construct a predictive model consistent with actual ground subsidence caused by liquefaction. Based on the analysis results from the Nankai Trough Great Earthquake Model Study Group, transfer learning was applied using vertical differences in the DEM (Digital Elevation Model) of Urayasu City, Chiba Prefecture, before and after the Great East Japan Earthquake as the actual subsidence amounts due to liquefaction. A neural network regression model was employed as the algorithm for this purpose. As a result, transfer learning using the pre-trained model improved the overall prediction accuracy of liquefaction-induced ground subsidence. This indicates that a realistic predictive model can be constructed by applying transfer learning based on actual subsidence data obtained from airborne laser surveys.

 We developed a new disaster learning tool, “Digital Our Timeline (D_Awatara).” The use of this tool can help students input their own actions and roles, as well as those of their family members, neighbors, and city officials over the time course of a disaster into a spreadsheet on the cloud. In the study, we implemented D_Awatara in disaster risk reduction education at three junior high schools. At all the schools we studied, the actions of the students and their families were described more frequently than those of neighbors and city officials. Schools that did not have sufficient tablets for each group at the time of implementation were described less frequently than other schools. Questionnaires administered before and after the class showed that students’ awareness of disaster preparedness increased in general, but “efficacy for the community” did not increase significantly in the school where the number of descriptions using D_Awatara was small. These results suggest that D_Awatara is an effective learning tool for disaster reduction and improvement of students’ “efficacy for the community, ” which may increase their desire to contribute to local disaster reduction. However, it is also clear that an adequate ICT environment is essential for the tool’s implementation.

 Landslides with human casualties often occur in Japan. In areas where such major landslides have occurred, the Geospatial Information Authority of Japan (GSI) produces slope failure and sedimentation distribution maps. However, in preparing these maps, the interpretation of slope failure points is carried out manually by specialists who look at satellite images of the affected area, which causes problems such as a lack of human resources, the burden on workers and the difficulty in quickly identifying the extent of landslide damage. The aim of this study is to develop a method for automatic detection of landslides using satellite images based on deep learning. As a result, we were able to construct a model which can detect landslides with an IoU of 0.641.

 This paper proposes a method to measure the amount of difference in road surface steps caused by an earthquake using LiDAR (Light Detection And Ranging), which measures the distance to an object and the shape of the object based on the information of reflected light from a laser beam. It is not possible to acquire point cloud data for the area shielded by an object. Thus, when a step is viewed from the top to the bottom, the Euclidean distance between two points cannot be obtained because there is an invisible area where the point cloud data of the step cannot be acquired. Therefore, in this study, the amount of step is obtained by approximating the point cloud data of the road surface to the equation of a plane in three-dimensional space, and the accuracy of this method is examined. As a result, we confirmed that by taking into account the invisible area, the amount of the step can be calculated more accurately for the step directly in front of the LiDAR equipment.

 In this study, we evaluated warning time distributions of Earthquake Early Warning (EEW) provided by JMA for six resent major earthquakes, and compared the warning time available to the population exposed to high seismic intensity by superimposing the interpolated estimated seismic intensity distribution based on the observed seismic intensity and the population distribution for each earthquake. In general, higher intensity areas are provided with shorter warning time. In inland crustal earthquakes, it is likely that warnings may not reach high intensity areas around the epicentral region in appropriate time. Conversely, in oceanic plate earthquakes, it is expected that warning time is effective even in high intensity areas. Next, spatial zoning was applied based on the temporal order of EEW announcements, P-wave arrival and S-wave arrival to remind people of the importance of appropriate safety actions for self-protection in each zone. Finally, we modeled the time required for the announcement of EEWs for prediction of warning time in future earthquakes.

 This study mainly focuses on buried sewer pipes. A model of a buried pipe with a 1,500-mm-long branch line was constructed, and the spatial correlation between ground surface and buried pipe displacement due to ground deformation during an earthquake was revealed through a combination of shaking table excitation tests and image analysis. The modeling of three types of ground deformation, liquefaction, ground cracking, and subsidence, was conducted to discover the spatial correlation between ground surface displacement and buried pipe displacement. The estimation of the ground surface displacement by image analysis provided us with good accuracy with extremely low variation for all types of ground surface deformation. The best modeling of the spatial correlation between ground surface and buried pipe displacement was done using a linear approximation.

 Based on the database of “Statistics on Water Supply” during the fiscal years 2008 through 2021, vulnerability factors of water distribution pipelines in Japan were evaluated reflecting pipe material, joint types and diameter. The long-term trend of the vulnerability factors was also compiled. While the ratios of both earthquake-resistant pipes and earthquake-resistance compatible pipes to all pipes increased by a factor of two for 14 years, vulnerability factors only decreased by a factor of around 0.8. A new index called “restoration difficulty factor” was defined as the product of vulnerability factor and the extension of water distribution pipelines per capita and evaluated based on 2021 version of “Statistics on Water Supply.” In the municipalities in the hard-hit area of the 2024 Noto Peninsula earthquake, both of vulnerability factors and the extension of water distribution pipelines per capita significantly exceed the nation-wide averages. Consequently, restoration difficulty factors were approximately six times as large as the average, resulting in lengthening of restoration works from water outage.

 In recent years, the seismic retrofitting of bridges through the replacement of existing steel bearings with isolation bearings has become increasingly common across Japan. Spherical Sliding Bearings (SSBs) are particularly notable for their reduced structural height, which minimizes construction space requirements compared to conventional laminated rubber bearings. The seismic isolation performance of SSBs is governed by their elongated period and energy absorption capacity, which are determined by the stiffness of the bearings and the friction coefficient between the sphere and the slider. This study proposes a novel performance assessment method for SSBs in bridges, utilizing dynamic data and Bayesian estimation techniques. Specifically, an adaptive unscented Kalman filter (AUKF) is employed to estimate key performance indicators and the restoring force characteristics of SSBs. The feasibility of the proposed method is validated using experimental data from shake table tests on an isolation bridge model.

 The behavior of structures such as bridges and viaducts during earthquakes includes not only horizontal motion but also rotational motion. Additionally, it has been understood that the behavior of ancillary equipment and vehicles on these structures during earthquakes is influenced by not only the horizontal motion at the top of the structure but also its rotational motion. Therefore, this study aims to understand the fundamental mechanisms of seismic rotational behavior for single-column and rigid-frame structures, theoretically deriving the rotational-horizontal ratio k_θ (rotation angle θ/ horizontal displacement δ) at the top of the structure. In this analysis, fixed-ground conditions were assumed, and the girder mass was modeled as a concentrated mass. Comparing the values of the rotational-horizontal ratio k_θ between single-column and rigid-frame structures, the ratio for the rigid-frame structure was found to be less than half that of the single-column structure. Furthermore, through frequency response analysis, the frequency dependence of the rotational-horizontal ratio k_θ was also identified.

 As a seismic resistance measure for road bridges, a design method that selectively ruptures the plate retaining bolts of rubber bearings when the action exceeds the design seismic motion level is investigated. To realize this design method, reinforcing bars are added to create the difference between the yield capacity and the maximum horizontal capacity of RC piers. In this study, the deformation performance of this RC pier model is evaluated based on the results of cyclic loading tests, and it is confirmed that the assumed damage scenario can be realized.

 After 1995 Southern Hyogo Earthquake, the seismic retrofitting of railway structures has been prioritized specially the structures with low design performance, but the number of columns to be retrofit is huge, and construction is difficult if the space under the viaduct is in commercial use. In this study, with the aim of improving the effectiveness of seismic retrofitting, a 3D finite element analysis with material nonlinearity is carried out on three-span RC rigid frame viaduct with mid-level beams with the parameters such as shear reinforcement of the columns and the presence or absence of seismic retrofitting of columns. As a result, it was confirmed that in unstrengthen viaducts where mainly the lower columns are damaged, retrofitting of only the lower columns can sufficiently improve performance, and that retrofitting of only the end or middle columns can significantly reduce the amount of top surface settlement. On the other hand, it is also confirmed that when the shear strength before retrofitting is small, retrofitting only the lower columns may increase the damage of the upper columns.

 The single spherical sliding bearing is a seismic isolation device in which a slider moves on a concave sliding surface. Highly durable sliding materials must be used in spherical sliding bearing in bridges. In this study, shaking table tests were conducted using a highly durable sliding material for bridges to examine the effects of velocity, surface pressure and temperature dependencies on dynamic behavior. As a result, the velocity dependency on of the friction coefficient increased with increasing velocity, and the friction coefficient tended to increase around zero velocity due to the stick-slip phenomenon. The friction coefficient was also increased with the increasing velocity, especially at low surface pressure. The coefficient of friction decreased with increasing temperature and increased at low surface pressure. A series of analyses l incorporating these dependencies was carried out to simulate the shaking table experiment, and the experimental results ware accurately simulated.

 Real-Time Hybrid Simulation (RTHS), which synchronizes dynamic loading tests and numerical analysis, is considered an effective method for evaluating the dynamic behavior of large structures. However, RTHS faces a challenge due to unavoidable control delays in actuator, which disrupts the correspondence between measured forces from the loading test and displacement responses from the numerical analysis, thereby reducing test accuracy. To address this issue, a force-based delay compensation method has been proposed. However, previous force-based compensation methods, such as T-Modification, have been reported to suffer from decreased accuracy due to noise in the measured force. In this study, a new force-based compensation method, which is robust to measurement noise and utilizes a simplified nonlinear model of the experimental component as prior information, is proposed. Verification experiments confirmed that the proposed method provides effective compensation even in the presence of measurement noise.