Level set methods and volume of fluid (VOF) methods have been widely used for computing immiscible-fluid flows. While it is well known that these methods have their own advantages, there are few examples that applied both approaches to the same benchmark problems and made a critical comparison of the characteristics from a user’s perspective. The present study is an extension of Ishikawa et al. [J. JSCE A2 76(2) I 439 2020], who compared the ACLS (a level set variant) and CICSAM (a VOF variant) methods mainly in pure advection problems. Here another VOF variant, i.e., the THINC/WLIC method, is added to the comparison. The three methods are implemented with the same Navier-Stokes solver and critically compared in fundamental gas-liquid two-phase flow problems in two dimensions in terms of accuracy and computational cost. In the dam-break benchmark test, where the surface deformation is large and the surface tension effect is negligible, not only the VOF variants but the ACLS method show sufficient mass conservation ability and provide an accurate prediction. In the static/rising bubble problems, the ACLS method accurately represents the surface tension force within the framework of the continuum surface force model. While the VOF variants are found to be less precise, introducing the S-CLSVOF method that efficiently constructs a signed-distance function from the volume fraction field improves the prediction accuracy significantly. As to the computational cost, the ACLS method is the most expensive in pure advection problems. In the two-phase flow computations, however, the cost associated with the flow solver is dominant, and hence there is no significant difference in the total cost.

 Most of the studies on CFRP bonded steel tubes have been based on FE analysis, and there is insufficient research related to the shear lag theory and the energy release rate for adhesive debonding at the CFRP end. This study proposed a design method for the energy release rate and the step length at which the energy release rate converges for multi-layered CFRP bonded steel tubes. The relationship between the step length and the energy release rate at the bonded end is summarized by numerical analysis of shear lag theory solved using eigenvalues analysis under multi-layered CFRP bonded steel tubes. In addition, the equation for the step length required for convergence of the energy release rate was derived and an approximate solution was given. By applying the proposed method to the design of the end steps of CFRP, the energy release rate can be calculated using a simple equation derived from the strain energy of the entire structural system.

 In the railway continuous girder, the knowledge about the dynamic response in the high-speed region has not been organized, and rational design by a practical evaluation method has been difficult. This study firstly organized and generalized the structural specifications of general railway continuous girders and, secondly, carried out comprehensive dynamic response analysis of continuous girders during train passage. The impact coefficient of the deflection of the continuous girder shows multiple maximum points at the resonance speed of each natural vibration mode. When the number of spans is odd, the 1^st and 3^rd modes are amplified at the resonance speed, and the number of spans is even, the 2^nd mode is amplified at the resonance speed. Dominant vibration modes become unclear with the increase in the number of spans and the span length, and the impact coefficient of deflection tends to decrease in the region where the train speed is less than 400 km/h. Based on the clarified dynamic response characteristics of continuous girder, a simple evaluation method of the impact coefficient with the applicable range up to 400 km/h has been proposed, and its validity has been demonstrated.

 This paper proposes a countermeasure for fatigue cracks that propagate from the weld root of U-rib to deck welded joints to the deck plate or weld bead of orthotropic steel deck. Specifically, the lower flange of the U-rib is removed and the U-rib and deck plate welds are welded from the inside of the U-rib as a countermeasure method. First, to confirm the feasibility of this countermeasure with structural changes, the load-bearing capacity, workability of welding, and effects on asphalt pavement were verified. Next, changes in the local stress properties of the focused welds and other areas due to the countermeasures were confirmed by finite element analysis. Finally, the fatigue durability of the countermeasure was determined by fatigue tests.

 In order to contribute to the realization of carbon neutrality in 2050, the authors have focused on the fact that some of the by-products of social activities have the ability to fix carbon dioxide, and have envisioned the creation of a carbon-capture urban environment using these materials. In this paper, we propose a prototype of a database of carbon capture performance of CO₂ fixation materials by selecting several actual byproducts and using the constant flow aeration type CO₂ fixation test that we have developed. Furthermore, using this database, we estimate the potential carbon capture performance of a specific industrial waste disposal site as an example, and show its effectiveness in comparison with that of forests. Furthermore, we reevaluate the carbon capture effect of the urban environment and discuss the concept of a new future society.

 Before the global spread of COVID-19, the number of cruise ship calls in Japan had been increasing rapidly. However, based on the investment in the development of the receiving environment, the situation of exempting port charges and not charging terminal facility fees was not sustainable for port management bodies, and it is no exaggeration to say that there was over-competition among ports. One of the reasons for this situation is that previous studies have not shown how much the difference in port charges with other ports affects the number of port calls. In this paper, we developed a simulation model of port selection and quantitatively analyzed the effect of port charges on the selection of port of call for cruise ships, with the aim of providing materials for shifting to appropriate inter-port competition and sustainable port operation for port management bodies. As a result of the analysis of the case studies of Tokyo Port and Yokohama Port, it is suggested that the reduction of port charges by exemption has no significant effect on the selection of ports of call, and that it is desirable for port management bodies to charge appropriately.

 National land policy in postwar Japan has been promoted with the aim of achieving a balanced development of the national land, however, population concentration in cities and depopulation of rural areas have become big issues. On the other hand, EU countries are mitigating population concentration in urban areas and population outflow in rural areas in comparison with Japan.

 One of the reasons for the population change is the difference of policies for agriculture, which is a major industry in the intermediate and mountainous regions. In the EU, agricultural policies are designed from a national land policy perspective to ensure not only farming, but also access to education and medical care, and in other words, to respect the citizen`s rights. In this study, we analyzed the common agricultural policy in EU from previous studies and administrative documents and compared them with those of Japan. Besides, we discuss and propose national land policy frameworks to deal with these issues.

 In the operation and maintenance of the expressways, expressway companies not only repair the deteriorated expressways and piers, but also take the countermeasures before and after disasters. In this paper, authors propose a method for selecting the areas around the expressways that need careful monitoring by using time-series satellite-borne synthetic aperture radar (SAR) images. The method starts with the time-series SAR analysis, and estimates the cumulative ground deformation of the strongly scattered points. Then, it estimates the mean cumulative ground deformation in the areas along expressways. The results of experiments demonstrate that the proposed method succeeds in detecting mountain deformation prior to the actual landslide, that originated from the heavy rain in the previous year. Whereas the results are not validated with the field measurements, it is found that the proposed method has potential to be used in the the operation and maintenance of the expressways.

 This study clarified the movement of residences (2007-2020) of households affected by the tsunami caused by the Great East Japan Earthquake on March 11 in 2011 by tracking based on the telephone directory. The main conclusions obtained are as follows. 1) The share of the migrant population from the 10 affected cities to the studied 9 major cities in Iwate and Miyagi prefectures exceeds 57%. 2) The analysis used the NTT telephone directory registrants in the affected 10 cities: 135,524 households and major 9 cities: 320,678 households. The registration rate of the telephone directory was about 61.5% of the number of households in 2012, and 46.9% in 2019. The current residents in the disaster area was found in 74.7% of those of before disaster and 74,000 households, of which 39.2% and 38,800 households moved after the disaster. The current addresses of 13,986 households, 35.70% of the relocated people, have been identified. The ratio against all former residents is 14.0%. 3) The full name matching method was applied to grasp the moving between cities and towns. Multiple matching (same full name) is about 50% of 3,800 households with matching, or 1,831 households. The addresses of old and new residences targeted in this study are stored as a database.

 Urban railways are being developed rapidly in a number of Asian countries. Due to lack of financial resources of the government, urban railway development by PPP project has been adopted in Asia. However, most of PPP projects have not been successful and the government had to deal with them. The purpose of this study is to provide the knowledge for decision makers of railway construction in Asia by conducting a factfinding survey on how long it will take to develop the area around the railway station and proposing a method to clarify the progress of development even in countries where accurate land use data does not exist. In this study, evaluated the detailed transition confirmation of development by NDVI for MRT Blue Line and Purple Line in Bangkok, Thailand. As a result of using this method, it is clear that the development is particularly active in 20 to 30 km square from the center in Bangkok, and the development along the MRT Purple Line is remarkable.

 For sustainable infrastructure development, it is essential to create an environment in which all companies, including small and medium-sized enterprises, can operate stably. However, in Japan, it has been pointed out for many years that the ``Exploitation problem'' in the subcontracting relationship between companies has become a major obstacle to the management of small and medium-sized enterprises, and its solution has been called into question. In this study, we performed an analysis that expanded the subcontracting definition used in quantitative analysis, which had never been done before, and an analysis that included the "construction industry", which was often treated as an exception. As a result, there is a possibility that the problem of exploitation is likely to occur in ``business-to-business transactions'', and it is indirectly suggested that the problem of exploitation has worsened since around 1980 in the manufacturing industry and around 1990 in the service industry. Furthermore, in the construction industry, the exploitation problem has been worsening over the long term since at least 1992, and it was suggested that subcontractors in particular may play a role as buffers for the economic fluctuations of prime contractors.

 In recent years, the increase in the number of vacant houses has become a problem in the field of urban planning. However, there is a lack of measures based on “psychological strategies” induced by psychological factors to promote behavioural changes. This study identifies the factors that increase the interest and enhance the behaviour of detached house owners toward the future of their homes and proposes psychological strategies based on them. We found that “life events of children” and “home acquisition” were identified as catalysts for the rise in the owners’ interest in the future of their homes and the inclination to take action. Furthermore, we found that more owners tended to remain only interested in the future of their homes compared to those who took action due to “life events of children”. This study also determines the method for providing information at the time of housing acquisition and marriage registration based on the results of the analysis.

 Typhoon 19th in 2019 was forecasted to have the strongest winds ever in the Tokyo metropolitan area, resulting in large-scale aircrafts evacuations from Haneda and Narita airports to airports across Japan, and some difficulties in coordinating to secure evacuation sites. Given the increase in the number of aircraft in the fleet and the increasing severity and frequency of natural disasters, it will be difficult to respond in a timely manner with the conventional aircraft evacuation scheme, and there is a growing need for a new preevacuation coordination scheme study and training. In this study, we analyzed the actual situation of aircraft evacuation during Typhoon 19th in 2019 based on web-based open data and interviews with the Civil Aviation Bureau and other organizations, and clarified the constraints and issues related to aircraft evacuation and temporary parking at airports. Based on these results, we examined the temporary aircraft parking methods at airports according to the emergency level, and conducted simulation analysis of the demand for evacuated aircraft and the capacity of the airports under several natural disaster scenarios, and discussed the feasibility and challenges of aircraft evacuation in Japan in the event of a large-scale natural disaster.

 In recent years, Japan’s total population has been decreasing and the number of elderly people aged 65 and over is the highest ever at 36.17 million as of September 2020. In past research on traffic behavior and health, it is said that using public transportation contributed to increase in the number of steps. However, there are few studies that calculated the effect of curbing health costs for local public transportation. In this study, we examined the effect of curbing health costs using steps count data of public transportation. We attempted to calculate the curbing health costs using the guidelines of the Ministry of Land, Infrastructure, Transport, and Tourism. Since it is difficult to extract only the step count data of using the shared taxi from the daily step count data, we calculated the curbing health costs of using public transport and multiplied these costs by the shared taxi usage. As a result, it was found that using the shared taxi reduces curbing health costs by about 6,101 yen per user per year.

 Although realization of carbon neutral ports is currently being pursued in Japan, there are few empirical studies on climate change measures in ports, and the gap between the practice and the research does not adequately support decision makers. This paper empirically examines the effectiveness of climate change measures at container terminals, using Hakata Port as a case study, which is leading Japan's port environmental policy by electrification and hybridization of cargo handling machinery and installation of roof shades in the reefer area, and also analyzes the feasibility of the measures based on economic analysis and the characteristics of port governance in Japan. Although the effectiveness of the measures was confirmed, it was found that it is difficult for terminal operators etc. to take the initiative in terms of financial feasibility, and that government initiatives, including subsidies, are important in terms of port governance.

 Among "regional experience seekers" who have attracted attention in recent years for regional revitalization in Japan, visiting regional experience seekers are expected to play roles as leaders in rural areas where populations are declining. For this study, after categorizing "visiting regional experience seekers" in Japan into 11 categories, we explored their suitability as leaders by quantitatively grasping the contents of activities in which they are engaged, the reasons for their involvement, and the actual locations of their activities. Results indicated the following: 1) Private-sector workers who telework and engage in community activities near their residences were most likely to engage in activities with strong ties to the community. 2) Such individuals were more likely than others to visit not only because of ties with relatives and friends, but also because of non-visiting relationships and introductions from contact points that support such ties. 3) The activities are often conducted in rural areas such as farming, forestry, and fishing related villages.

 Revitalizing urban streams that do not hold people’s interest requires constant collaborative efforts by local actors. This study aims to clarify the process of and collaboration involved in the realization of the “Everybody’s Dream Waterway” project in Zempukuji Park, Suginami Ward, Tokyo. The realization process consisted of four stages: 1) long-term fostering of local actors through studying and experiencing the river, 2) conceptualization of a shared vision triggered by efforts to bridge multiple actors, 3) planning and discussion prompted by project implementation, and 4) establishment of a community-based organization and an operational arrangement facilitated by an agreement over a set of principles concerning a shared management scheme. By applying the concept of “bridging” as an analytical framework to understand the collaborative efforts, and by analyzing the process from perspective of convening, translation, cooperation, and mediation, the article explains how the urban stream restoration project was realized through the collective action of the community, which was made possible by the existence of a bridge between citizens and schools. The bridging work created a space that spurred the collaboration between the stream restoration movement as a civic activity involving a diverse range of local actors and the ongoing river-based curriculum at elementary schools.

 Optimization of the reaction time and temperature was investigated so that the API method can be applied to fly ash, which exhibits various physical and chemical properties associated with variations in the quality of fuel coal. When a suspension of fly ash, cement, and water mixed at a mass ratio of 1:1:40 was reacted at 80°C for 18 to 48 hours, the pozzolanic reaction did not converge, but the API value obtained under the reaction conditions of 80°C-28 hours showed a good correlation with the activity index at 28 days and 91 days of age. Cross-check tests were conducted by five laboratories using three types of fly ash with different reactivity at three repetition rates. The repeatability of the API method at three repetitions and the reproducibility of the evaluation values among the five laboratories were good, indicating that the API method has a relatively small error factor.

 In Japanese expressway pavements, deeper layers are damaged due to the change of surface materials from dense graded pavements to high-performance pavements and the decline in structural load bearing capacity caused by deterioration. In practice, stratified repair is conducted according to damage status, but the recovery of structural load bearing capacity has not been measured in quantitative ways, so the relation between the effects of stratified repair and structural load bearing capacity has not been clarified. In this study, the variation in load bearing capacity of a pavement structure is modeled as a combined process, which is composed of (1) a process of deterioration with time and (2) a process of recovery through repair. With this, it will be possible to not only predict the decline in structural load bearing capacity, but also quantify the recovery through repair with a transitional probability. Furthermore, the authors discuss the usefulness of the proposed model, by applying it to real expressway pavements.

 The purpose of this study is to apply a binder (IBPM) using fly ash, ground-granulated blast-furnace slag, calcium hydroxide as an alkali activator, etc. to various precast concrete (PCa) products manufactured by steam curing. The effect of fluctuations in fly ash quality on compressive strength, the relationship between water-binder ratio and compressive strength were clarified, and shrinkage, chloride ion diffusion coefficient, sulfuric acid resistance, abrasion resistance and freeze-thaw resistance were experimentally investigated. By manufacturing full-scale specimens of box culvert, segment, Hume pipes and manhole, it was shown that normal compactions by vibration or centrifugal force can be applied and that the PCa products have sufficient load bearing capacity.

 In recent years, the situation surrounding social infrastructure development has changed drastically, and Civil Engineering Consulting Firms are accordingly required to expand and diversify the scope of activities. The purpose of this study is, with an eye on the early-stage Social Acceptability that could be one of the factors causing delay and inhibition in geothermal development process, in the development of renewable energies for the realization of a decarbonized society, to examine the application of such project management methods, that have already been established and thus generally utilized in the construction management area, into a process of consensus building as a method that contributes to the solution of the problems. More specifically, the activity policy in reference to the project stakeholder management based on the PMBOK is proposed, and then a systematic implementation method of consensus building activities, consisting of eight stages and three systems is presented, based upon the verification result of implementing multi-year projects in practice. This study proposes versatile and systematic activity methods in future geothermal development field.

 Sewer concrete pipes are buried structures, so it is difficult to carry out thorough inspection in the entire management area. On the other hand, even if inspection cannot be conducted, the information on attributes that would influence the deterioration of pipes can be used for the entire area in many cases. In this study, the authors predict the deterioration of pipes by using partial inspection data, and propose a methodology for predicting the deterioration of all pipes, including uninspected ones, with a spatial mapping model that expresses the deterioration heterogeneity of pipes and the spatial relation of attribute information by using the regressive kriging method. Furthermore, the authors visualize the spatial integration of deteriorated pipes, whose condition state is low, through dual kernel density estimation, in the condition state distribution produced based on the results of deterioration prediction, and extract rebuilt and renewed areas. Lastly, the proposed method is applied to the sewer pipe data of Osaka City, to investigate its usefulness.

 Heavy rains severely inundated Kuma and Hitoyoshi in Kumamoto, Japan, in July 2020. Due to the COVID-19 pandemic, many people avoided going to evacuation centers and stayed in their damaged homes or homes of relatives and acquaintances. In addition, only Kumamoto residents were allowed to volunteer, resulting in an insufficient number of volunteers. Thus, analyzing the situation of this unique disaster is important, and location-based big data appears promising for the analysis. In this study, we attempted to understand the actual situation of evacuees and volunteers during the disaster by using mobile spatial statistics of aggregated data and GPS-based individual tracking data. Mobile spatial statistics revealed that the number of people decreased significantly in the inundated areas at night. Using GPS-based individual tracking data, we developed a method for extracting volunteers and calculating the time spent at volunteer centers.

 An earthquake occurred in Central Sulawesi Province, Indonesia in September, 2018. It killed about 4,500 people by Tsunami which attacked within few minutes from earthquake and by huge landslides brought by liquefaction (Nalodo), which is a rare phenomenon in human history. The author, who was dispatched as JICA Expert to National Disaster Risk Reduction Agency in Indonesia, assisted Government of Indonesia in composing Reconstruction Master Plan with the help of other JICA Experts, Japanese academic researchers and consultants. In this process, the author gave technological explains of Tsunami dike and clarified the mechanism of the large-scale landslide by liquefaction. The result of dedicated efforts by Japan had Government of Indonesia entirely rely on Japan when they faced or disaster risk reduction policies such as large-scale floods. The author analyzed the reason why Japan got trust of Indonesia, and provided a helpful perspective on Japanese Official Development Assistance.

 Since rivers on an island in general face water scarcity, grey infrastructures have been developed for water use and flood control, of which anthropogenic impact has resulted in severe degradations of aquatic and terrestrial ecosystems therein. It is therefore necessary to conduct comprehensive studies considering multiple aspects including physical environment and natural ecosystems. This study aims at understanding the longitudinal distributions of instream physical habitat conditions and fish species with consideration to water infrastructures in the Miyara river watershed on Ishigaki island. The watershed was segmented into six study zones based on the locations of water-related infrastructures such as dams and weirs as well as tidal effects on river flows. As a result, we observed 29 families, 72 fish species (namely, 7 genuine freshwater fishes, 17 diadromous fishes, 37 peripheral freshwater fishes, and 11 marine fishes) in the Miyara river watershed. Instream physical habitat conditions such as water temperature and water depth showed statistically significant differences among the study zones. The number of fish species was largest in the estuarine zone, and decreased with the distance from the river mouth and the presence of grey infrastructures. The effects of such infrastructures on the longitudinal distributions of fish species were found to be deep, stagnant water flows and the movement barrier at the upstream boundary of tidal dynamics in the river system.

 It is necessary to develop a management methodology for evaluating and improving training programs to ensure that engineers possess the essential technical capabilities to maintain aging infrastructure. However, as infrastructure maintenance significantly depends on tacit knowledge, it is challenging to evaluate training effectiveness because the overall picture and components of the target technical capabilities are unclear. In this study, the effect of training on road bridge inspection in improving technical capabilities was evaluated. An example of technical capabilities embodied in a previous study by the authors based on Bloom’s Taxonomy developed in the field of education was used. It was shown that improvement plan could be formulated. Furthermore, a methodology was developed to evaluate and improve training programs for infrastructure maintenance.