A key to achieving "basin flood control" is to restore and utilize the infiltration and storage functions of rivers and basins. In this study, by taking advantage of the riverbank seepage storage phenomenon inherent in rivers, the possibility of reducing flood flow by temporarily storing flood flow on the riverbank was investigated. Based on the governing equations of stream flow and groundwater flow, the interaction in coupled system of the river channel and the riparian permeable layer was modeled. A wide range of permeability from fine sand to gravel was set respectively for the case where the riparian permeable layer spreads semi-infinitely from the river channel and the case where its spread is limited to a finite range. By flood routing with the interaction between stream and groundwater, the extent to which the presence of the riparian permeable layer can contribute to reducing flood flow was quantitatively evaluated. The results showed that if the ground in the riverside area is sandy and gravelly, it is possible to sufficiently reduce flood flow through riverside infiltration storage.

 In recent years, there are many underground passages developed by private sectors in urban development. But actual situations and problems of planning, maintenance, and management are not clear. The purpose of this study is to work on the improvement of underground passages through future private development in Tokyo by conducting surveys and interviews, and sorting out their situations and issues. It shows that underground passages of private sectors and transferred to railway company or road manager are important for formation of pedestrian networks. But there are issues; public nature of the plan is not sufficiently considered in the adjustment of road occupancy, discussions at the development stage take time, it is difficult to maintain facilities with more than the minimum traffic function, it is difficult to set up revenue facilities to cover management costs. It became clear that the system at the planning stage and the system at the maintenance and management stage should be operated in coordination.

 In the case of a fire, smoke that causes poor visibility and prevents tunnel users from their smooth evacuation may put their lives in danger. Smoke should be controlled not to flow into evacuation passages so that the environment of the passage is maintained as safe area. When a fire occurs in a tunnel of Japanese expressway, the passages will be pressurized by fans and the velocity of the airflow from the passage toward the main tunnel will be maintained at 2 m/s at the cross section of the emergency exit. However the velocity is basically used for preventing smoke from backlayering in main tunnel, therefore it is necessary to determine the proper airflow velocity for the purpose. This paper describes the experimental results about the required airflow velocity that smoke cannot flow into the emergency passage.

 Two dimensional unsaturated seepage flow finite analysis code, which can consider measured initial water content by using semi-iterative solution method and can express scanning water retention curve proposed by Luckner, had been made and verified by comparing observed seepage flow behavior in model embankment with analysed one during rainfall. At the start of analyses, calculated initial water content could be the same with measured one at corresponding observation point. Main rainfall events from 2004 to 2020 were used to verify the code, the all analysed results of considering initial water content and water retention scanning curve were agreed well with measured one without adjusting material parameters a lot at each rainfall event.

 In the aftermath of the Great East Japan Earthquake, resident-led recovery was emphasized, and many areas promoted relocation to higher ground. However, the planning process for large-scale land elevation projects and the incorporation of residents’ opinions remain unclear. This study focuses on the implementation, location, and area of land elevation, which are determinants of development scale, and analyzes the planning processes of seven large-scale relocation-to-higher-ground areas and four in-situ reconstruction areas as comparison targets.

 As a result, it was found that the implementation, location, and area of land elevation fluctuated throughout the formulation of the basic reconstruction plan and project implementation, influenced by various factors such as geotechnical conditions, landowner agreements, and residents’ preferences. To address these changes, municipalities employed various methods to grasp residents’ opinions through routine communication and devised strategies in the planning process to ensure smooth plan formulation and implementation.

 This study summarizes the characteristics and design features of a section before and after a severe-disaster special emergency project is performed on the Tsukumi River, which aims to create a river space that people would wish to continue to live. The effect of this project on landscape improvement is discussed by clarifying the changes in local residents’ awareness and behavior through interview surveys. Consequently, the following are identified: 1) the residents’ evaluation of the development and the importance of cooperation among the project units and integrated development with the city; 2) the promotion of the desire to continue living in the area and civic pride through landscape conservation; and 3) the possibility that the special emergency project, which promotes landscape conservation and use, not only improves disaster preparedness but also contributes to mutual aid during emergency.

 In this study, a new Cathodic Protection Method of rebars in RC structures by electromagnetic induction was proposed. The principle of the proposed method is that the eddy current, which is generated on the rebar surface due to electromagnetic induction in a non-contact and non-destructive manner, is used as a protective current to suppress the corrosion current formed between the rebar surface and its surrounding environment. In this paper, it is noted that the feature of the eddy current on the rebar due to the between the experimental and the analytical results was discussed, and then the performance of the corrosion protection proposed by this paper was estimated. Finally, it should be noted that the proposed method is applicable to prevent the occurrence of corrosion on rebars due to the comparison with the experimental estimation.

 This study investigates the radio wave transparency of different types of concrete and the influencing factors, and finds the conditions that improve radio wave transparency. The goal is to actively control the radio wave propagation environment through the physical properties of the concrete itself, rather than through communication devices. The study begins by reviewing the theoretical equation for electromagnetic wave propagation in concrete and the water form in concrete. It then discusses the effect of water on radio wave transparency. Radio wave transparency tests were conducted on plate specimens with controlled internal water content. The results confirmed that reducing the evaporable water by low water-powder ratio alone did not improve the radio wave transparency. However, simultaneous reduction of evaporable and non-evaporable water using geopolymer instead of cement paste in addition to low water-powder ratio greatly improved the radio wave transparency.

 In this study, a full-scale specimen made of reinforced concrete with a part of the specimen periodically sprayed with salt water was subjected to a corrosion investigation, assuming that the structure is supplied with anti-freezing agent by leakage water. From the results of the corrosion investigation, it was confirmed that the corrosion condition was not uniform even within the area where the salt water was sprayed and that steel corrosion occurred even outside the area where the salt water was sprayed. Localized corrosion was found to have a pH 2-3, suggesting crevice corrosion. On the other hand, Green Rust was observed at several locations, suggesting that steel corrosion in concrete is not normally expected to occur in wet environment. The reason for the non-uniformity of steel corrosion is not only the crevice structure between the steel and the black skin, which has been pointed out in previous studies, but also the crevice structure due to bleeding between the steel and the concrete.

 On slopes with few man-made structures in mountainous areas, permanent scattering points that can accurately measure displacement cannot be obtained from PSInSAR analysis using satellite SAR data. The corner reflector is installed at the desired measurement point, which becomes a permanent scattering point and enables highly accurate measurements. In this paper, the accuracy of displacement measurement at corner reflector was verified by comparing the forced displacement of corner reflector with the displacement measurement results from PSInSAR analysis using Sentinel-1 SAR data. Slope displacement monitoring of with displacements as small as about 1 mm to 2 mm per month was carried out by PSInSAR analysis using Sentinel-1 SAR data. Small, inexpensive corner reflectors were installed to verify that displacement measurement is possible at the corner reflectors as well as at the artificial structure locations.

 When determining noise barriers for individual residences along roadsides, it is necessary to determine not only the height but also the length of the barrier. However, conventional cross-sectional prediction methods can assess height but not the required length. Three-dimensional prediction methods allow for the consideration of both height and length of the noise barrier, but they are not widely used for noise prediction along roadsides due to computational complexity. In this study, we investigated the factors influencing the required length of noise barriers and proposed a formula for calculating the length of noise barriers using the cross-sectional prediction results. Additionally, we validated the suitability of the proposed formula using the three-dimensional noise prediction software. The results showed that the proposed formula can reasonably determine the length of noise barriers satisfying the noise conservation goals. Furthermore, we proposed a method to achieve evaluation criteria with the optimal combination of length and height of noise barriers and verified its effectiveness.