The deepening of channel and basin causes the increase of sedimentation in the channel and basin. On the other hands, the prediction of sedimentation by numerical simulation situated along river mouth to costal area is difficult due to complex behavior such as inflow from river, advection-diffusion of suspended load by flow, and bed load by waves. In this research, the estimation of sedimentation characteristics after deepening the channel and basin of Lach Huyen Port were carried out based on the long-term field monitoring after the completion of dredging works. The reproducibility of sedimentation in the site was also verified by numerical simulation considering the estimated characteristics.

 As the result, the differences of sedimentation trend were confirmed depending on the relationship between river discharge and waves, and the sedimentation trend was reproduced well by the numerical simulation considering the relationship.

 As the characteristic parameters to consider the damage potential of the stability of coastal dike associated with the shoreline recession, beach width in front of the coastal dike, which can be easily confirmed in the field, and cross-sectional area of the beach between the berm height h_R and the depth of closure h_c were considered. The examples at the Ryuyo, Hamamatsu-goto, and Hamamatsu-shinohara coasts were investigated. On the basis of the time changes in beach width obtained from the past aerial photographs and the cross-shore area of the beach calculated from the annual bathymetric survey, the critical limit for damage of the coastal dike was obtained.

 On August 13, 2019, the seawall protecting Route No. 134 running along the coast was destroyed, and the walkway along the road collapsed. The direct cause of the failure of the seawall is due to high waves associated with Typhoon No. 10 crossing the Japanese archipelago, but the change in the seawall was initiated from 2 months before the damage. Field observations were carried out before and on August 20 after the storm, and the causes of the damage were investigated. Furthermore, shoreline changes of the coast were investigated using aerial photographs. It was found that the beach erosion of the coast was triggered by the discharge of longshore sand turning around the tip of Inamuragasaki Point located at the east end of the coast.

 Typhoon No. 19 hit the Shimizu coast in Shizuoka Prefecture on October 12, 2019, recording the maximum wave height on this coast. During storm waves associated with this typhoon, no damage was recorded in the newly-constructed new-type groin with the combination of piles and concrete blocks, but damage occurred in a longitudinal ordinary-type groin. The shoreline significantly receded and water depth increased immediately north of the groin, so wave run-up over the seawall and deposition of gravel inside the seawall increased. The wave and meteorological conditions during this typhoon and wave-overtopping and erosion damages were investigated.

 Typhoon No. 19 hit Shizuoka Prefecture on October 12, 2019 and high waves were incident to the Ryuyo coast facing the Enshu-nada Sea. During this typhoon, severe beach erosion occurred in this area, and coastal dike composed of the earth material was entirely destroyed in an area with a narrow foreshore, and inundation occurred inland of the coastal dike downcoast of detached breakwater No. 6. Field observation was carried out on October 29, 2019, after the storm together with the photographing of UAV imageries. The change in longitudinal profiles were investigated, and it was shown that a large amount of sand was transported in the offshore zone as well as the westward longshore sand transport. Furthermore, the mechanism of beach changes was studied in terms of the relationship between the wave angle and the direction normal to the shoreline.

 In order to clarify the dynamics of sediment transport when water is discharged in the direction perpendicular to the shoreline on the coast where longshore sediment transport is dominant, field experiments of sediment movement using colored sand tracer were carried out on the water discharge at the Hamaoka Nuclear Power Station. The experiments were conducted for three months in the winter season when eastward coastal currents were dominant. 6.6 t of blue colored sand was injected into the water outlet of the power plant, and the appearance of colored sand was observed in the sea area in front of the water outlet and the neighboring coast. As a result, the colored sand in the offshore area was found at a depth of less than 7 m, which implies a high probability that sand movement by the discharge water does not reach the closure depth for sediment movement (h_c = 10 m) in this area. Moreover, the colored sand on the beach was found on the east and west ends of the survey area (about 12 km in the coastal direction); thus, it has become clear that sand movement by a longshore current is widespread quickly.

 The Maejima Tombolo Tidal Flat located in Higashihazu-cho, Nishio City, Aichi Prefecture is a tidal flat without rivers to supply sediment. On this tidal flat, seasonal morphological changes and eastward of shallowest part movement of the tidal flat have been confirmed from before. In recent years, this morphological change has been large and it has begun that the characteristics of the change different from previous changes are shown. Local fishermen are concerned about the shrinkage, disappearance and environmental degradation of this tidal flat from now on. The target area repeats drying and submergence by tide. It is difficult to grasp detailed sediment transport and bathymetric change because the number of data acquisition and amount of data are limited only by field observation and analysis. In this study, investigation of the detailed morphological changes on the tidal flat is conducted by using field observation and numerical simulation together. As a result, it was demonstrated that the numerical simulation could mostly reproduce the flow field around the tidal flat. Sediment transport on the tidal flat only in one cycle of a tide was also confirmed by this numerical simulation.

 In this paper, the authors carried out numerical simulations of tsunami-induced topography change around a harbor using various sediment transport formulas in order to clarify the effect of the difference in the formulas on the analysis. A full three-dimensional flow model was adopted for the tsunami calculation. According to the simulations considering only bed-load, we could see that non-equilibrium bed-load transport affected to the sedimentation in the harbor. Moreover, by comparisons between the targeted experimental result and the simulated results using various suspended-load formulas considering non-equilibrium bed-load transport, the Ikeno et al. formula and the Itakura and Kishi’s formula were found to reproduce the experimental result well under the calculation condition we set in this paper.

 On the Kozu and Maekawa coasts in Odawara City, facing Sagami Bay, severe wave overtopping damage and erosion occurred due to the storm waves associated with T1919, which hit the coast on October 12, 2019. Since severe wave-overtopping damage also occurred during T0709 which attacked on September 7, 2007, the crown height of the seawall was raised by 1.5 m, resulting in the crown height of 10.5 m above the mean sea level. Nevertheless, severe wave-overtopping occurred. Wave-overtopping damages and erosion of the Kozu and Maekawa coasts by T1919 were investigated with reference to the damages caused by T0709 and T1115.

 Most of fishing ports are located in the surf zone. As a result, channel sedimentation has become a serious problem. As an example, when planning groins to control littoral drift and nearshore current, annual maximum wind waves heights is used as the external forces condition. However, the effect as expected is not obtained in many cases. In this paper, we present relationships long period waves and channel sedimentations from the observation data and numerical simulations on waves and currents.

 Large vessels are equipped with large thrusters and jet flow caused by thrusters leads to the scour around quay. However, there are few studies about the velocity around quay caused by jet flow and the relation between the position of the thruster and quay or sea bed. In addition, existing equations, known as Dutch method and German method, for predicting bottom velocity from jet flow are based on the limited experiments and the calculated values from these equations have large gap each other.

 In this study, we performed a few experiments and numerical simulations to discuss the relation between the relative position of the thruster from quay and sea bed and bottom velocity from jet flow and scour shape. As a result, we found out that the predicted bottom velocity from proposed equations underestimates the experiment depending on the conditions, and scour shape has strong relation between the collision of jet flow and quay in Dutch formulation.

 In order to reduce the motion of a floating caisson, the effectiveness of a footing was investigated in terms of its width. Free oscillation experiments showed that the natural period of the pitch and the nonlinear extinction coefficients of the heave and pitch increased with the relative footing width. Forced oscillation experiments showed that the amplitude of the heave became large when the wave period was the same as the natural period of the heave. Similarly, the amplitude of the pitch increased when the wave period was one or two times larger than the natural period of the pitch. These suggested that it is essential to determine footing width considering the findings of this study.

 A temporary floating breakwater has been proposed to keep calm wave conditions in an offshore construction site. In this study, its wave damping mechanism was investigated from numerical simulations. Numerical results showed that the trend of the transmission coefficient can be predicted reasonably well. Furthermore, an energy damping coefficient of the breakwater changed depending on the breakwater width relative to the wavelength, and the change was explained in terms of vortices formed inside and under the breakwater. From numerical experiments, it was found that the barrier height of the breakwater and the free water depth poured inside the breakwater for most effectively reducing transmitted waves were dependence on the breakwater width relative to the wavelength.

 In recent years, large-scale bollards (tractive force: 1500 kN and 2000 kN), which are not described in the Japan’s Standard Specifications for Port & Harbour Works, have been installed at quay walls because of enlarged ships especially cruise ships calling in Japanese ports. The main opinion of mooring workers is that the head of large-scale bollards is too large and too tall, and that’s a big burden and a cause of deterioration of work efficiency. In this study, we first organized the design concept for the head of large-scale bollards based on the existing method. Also, we carried out a survey on the use of large-scale bollards for mooring workers. We studied a miniature head, which is expected to improve work efficiency in mooring work, while ensuring safety during mooring for the bollards. As a result, we clarified that the bollards with a tractive force of 2000 kN can be made the same outer size as the conventional 1500 kN commercial type or smaller than that.

 A parallel side length and above-water projected areas of a ship are used for calculating the ship berthing energy in fender design and for estimating the tractive forces of the moored ship by wind loads in mooring post design, respectively. Since these parameters are not generally disclosed as ship specification data, it is difficult to obtain the accurate values of them for a design ship. In this study, we performed the statistical analysis using the data collected through questionnaire surveys, and then we presented the regression equations of the above parameters for 8 kinds of ships in full load and ballasted conditions.

 In this study, the applicability of the elastic mooring system to a large floating body is described. The elastic mooring system is a mooring method that incorporates an elastic body bundled with highly stretchable rubber rope between mooring lines that connect anchors and floating structure. Even if the position of the mooring cable attachment point of the floating structure moves up and down, an appropriate tension always acts on the elastic mooring system, and it can be expected to suppress the oscillation of the floating structure, and prevent the mooring line from breaking due to excessive tension. However, the above-mentioned elastic mooring system with excellent performance is limited to use for mooring small and medium-sized floating structures such as piers and aquaculture facilities, and has never been applied to large floating structures exceeding 500 m. In this study, the motion response characteristics of a large floating structure moored by an elastic mooring system were grasped, and the results were compared with those of a catenary mooring widely used as a mooring device for a floating structure. As a result, even if the elastic mooring line was one-fifth the length of the catenary mooring, the response was more stable than that of the catenary mooring. And, even under the maximum external force condition of the year, the tension generated in the mooring rope was less than 40% of the breaking load, the applicability of the elastic mooring system to the large floating structure was confirmed.

 In this study, we analyze reports by the JTSD (Japan Transport Safety Board), with focusing vessel collision accidents with mooring facilities and accidents by dragging anchor in Japan. As a result, this study reveals that most of the vessel collision accidents (about 70% of total:618 cases) occur when a vessel is approaching a mooring facility and strong winds (exceeding calss-3 on the Beaufort wind scale) blowing form the sea is the dominant factor. And apparently sever accidents as to deactivate port function are frequently caused by a collision with a vessel and crane or a collision with a vessel bulbous bow and a mooring facility. Regarding dragging anchor, the data (total: 27 cases) shows that it tends to occur when average wind speed exceeds more than 10 m/s and its maximum velocity reaches about 0.5 to 3 m/s.

 Recently, the application of precast beams is increasing for the purpose of labor saving at construction sites. In the past, authors devised a double-square joint (referred to DS joint) as a bar joint structure for precast superstructures of port piers. In this study, bending load tests for DS joint of precast beams were carried out by changing the size of beam section and width/length ratio of square shaped bar in closure area. A practical scope of application for DS joint was proposed by considering the flexural rigidity, bending load capacity, crack behavior and strain distribution in the beam section.

 In this study, we focus on developing an economical seismic retrofit method for pile supported wharf by retrofitting damping member. The effective setup for damping member such as its damping material, installing angle and axial stiffness with considering effect of frequency characteristic of input wave was examined through the shaking table test. The targeted wharf had depth of 10 meters with three rows of steel pipe pile without retaining wall and backfill soil. The five kinds of damping member model using damping rubber were installed between piles as its installing angles of 30, 45 and 60 degrees were set between all the piles. The effect of the retrofitting damping member was to reduce the maximum displacement of the wharf by sharing the bending moment of pile head and increase the damping constant. This effect was improved in large energy absorption case of damping material and 60 degree of installation angle caused by relatively large axial displacement of damping member.

 In the evaluation of site amplification factors for input ground motion of port facility, it is desirable to use an evaluation method based on earthquake measurement at a target point. If this evaluation method based on earthquake measurement is not possible, simple methods such as those based on microtremor measurement and those based on empirical formulas are applied. Although estimation errors are not obvious, it is conceivable that accurate estimation of site amplification factors by the simple evaluation method can be lower than the evaluation method based on earthquake measurement. Therefore, estimation errors of site amplification factors by the simple evaluation methods is evaluated using the velocity PSI value and seismic coefficient for verification of mooring facilities. Then, considered some factors that cause estimation errors in the ground motion estimated by the simple evaluation methods based on microtremor observation.

 In this paper, the effectiveness of the partial solidification improvement of the ground in front of cantilever steel pipe sheet-pile river revetment to prevent liquefaction was evaluated by FEM analysis and centrifuge model tests. We investigated and formulated the design method for the river revetment using a simple and rational beam-spring model. Moreover, we verified the seismic performance of the river revetment constructed with that design method against the level 2 earthquake by means of 2D effective stress analysis using program "FLIP".

 In the Great East Japan Earthquake, tsunami overflowed coastal levees, and the water flow destroyed many levees. After the disaster, various countermeasures have been proposed, one of which is to maintain the height of the levee top while permitting the destruction of embankment slope. The present study also investigated this method, constructing the cement-treated-soil walls inside the levee. The levee models in which wall or grid-type improvement was embedded in the centre were shaken in centrifuge. As a result, it was confirmed that the ground was liquefied by shaking and the embankment slope collapsed, but the height of the top was almost maintained, and the improved ground was not damaged. They successfully showed the efficacy of the proposed method.

 Model tests and numerical analyses were conducted to propose the effective analytical method for quay walls in which main body structure was constructed by deep mixing method. In the model tests, dynamic behaviors were examined based on a series of centrifuge model experiments. In the reproduction analyses, dynamic behaviors were simulated using the finite element analysis code FLIP, and the validity of the numerical analysis results was verified through comparison with model experiment results. As a result, the numerical analyses were in good agreement with the results of the centrifuge model experiments, and it verified the effectiveness of the adopted analytical method for the quay structure. In addition, it was confirmed that the cross-sectional conditions such as the width and depth of the improved body affected the quay behaviors.

 In this study, in applying the suction bucket structure to the foundation of an offshore wind turbine, in order to evaluate the bearing force characteristics of the structure against unidirectional horizontal loads and repeated horizontal loads, a soil vessel experiment was carried out in 1 G gravitational field. Through this study, the experimental result was consistent with previous studies in Europe that were prior to this technology. Moreover, it was possible to set the design load that satisfies the allowable inclination angle by using the ultimate strength of the structure.

 It is difficult to estimate the axial resistance of a large-diameter steel-pipe pile used as an open-ended pile. Partition plates may be attached to increase point bearing capacity of the pile, however, its effect is not clear. This paper reports the details of the rapid load test of a large-diameter open-ended pile with a partition plate performed at Yatsushiro Port. Base on the test results, both the shaft resistance ratio and the plugging effect ratio were examined, and it was confirmed that the result consistent with past studies were obtained. The authors plan to proceed with the design and construction of structures based on the information obtained.

 In Japan, a large bearing capacity is expected for the pile in port structures using a pile foundation as an enlargement of the facility and a change in the type of structure. However, an estimation of the bearing capacity of deeply embedded piles with a large diameter has complex problems such as an increased bearing capacity because of a deep embedment, and the plugging effect is decreased when using large diameter piles. In this study, the double-pipe model pile that was used for measuring inner frictional resistance and the resistance of actual part separately. As a result, the resistance of actual part is greatly affected by plugging effect, and it changes anomalously.

 This paper discusses the experimental findings pertaining to the instability of the suction bucket foundation for wind turbines or offshore structures due to wave-induced liquefaction in sand beds. The emphasis of the experiments was placed on investigating the relation between the downward progress of liquefaction and the start of significant displacement of foundation bucket. A range of wave tests using a drum centrifuge was performed under a centrifugal acceleration of 70 gravities. The suction bucket foundation started moving significantly as soon as the liquefied zone advanced to the soil depth corresponding to the depth of the bucket tip. The experimental results also show that embedding the bucket tip in the dense layer with a thickness corresponding to 1/3 of bucket skirt length prevented instability of the foundation of suction bucket.

 This paper assessed the possibility of wave-induced liquefaction in seabed near Japan coast using Ocean Wave Information (NOWPHAS). Liquefaction potential at each observation point was assessed based on the comparison of the cyclic stress ratio, which expresses the severity of waves on the seabed, and the critical cyclic stress ratio below which liquefaction does not occur under progressive waves. Theoretical analysis considering cyclic plasticity of sand was validated against centrifuge wave tank tests under irregular waves and then applied to a risk assessment of the field. It was found that severe waves whose cyclic stress ratio exceed the liquefaction resistance in the loosely deposited seabed of sand have occasionally attacked Japanese coast. The analytical results showed that the excess pore water pressures developed and dissipated as the wave height increased and decreased, and continuous severe waves brought about liquefaction.

 Data of simple CU test, which is the triaxial compression test of clayey soil after the simplified recompression procedure, in ground surveys for port projects were collected at 6 ports in western Japan. The qualities of cohesive soil samples were evaluated based on the relationship between the shear strength obtained by the unconfined compressive strength S_u(UCS) and the simple CU strength S_u(SCU). In the result, 276 samples of 6 ports were classified into zone-I (the sample is good or very good)50.7%, zone-II(the quality of the sample is at the appropriate level)25.0%, zone-III (the quality of the sample is poor) 10.1%, and zone-IV (the quality of the sample is very poor) 4.1%.The average level of the quality was slightly higher than the “appropriate level”.

 Horizontal ground with different deposition directions were prepared and wave loading tests were carried out in a channel in a centrifugal loading device. As a result, the ground with a 30° deposition angle to the wave direction led to liquefaction relatively quickly. Soils with 0° and 150° sedimentation directions showed similar excess pore pressure accumulation rates. Next, the experimental results are ware simulated by using a strain space multiple mechanism model accounting for initial structural anisotropy. In this study, the results of the analysis were investigated in detail, and the differences in liquefaction properties of the ground with different sedimentation directions were discussed.

 The quantitative evaluation of the improvement effect is important in the design of the frontal ground improvement to increase the passive resistance of gravity-type caissons and other anti-soil pressure structures. In the case of increasing the passive resistance to soil pressure from the ground behind the quay wall by solidifying the front of a steel pipe sheet pile in a normally compacted clay ground, the mechanism of passive resistance and the relationship between the extent of improvement and the effect of improvement are unclear.An existing design method similar to the present case is a simple design method using a beam-spring model. However, this method is intended to be applied to sandy ground, and its applicability to clay ground has not been confirmed. In this study, the applicability of the design method using a beam-spring model to solidify and improve the front of an existing gravity-type quay wall using steel pipe sheet piles was verified by centrifugal model tests.

 In a reclaimed seawall maintained using water impermeable sheets, seawater is exchanged between inside and outside of the embankment through the rubble mound base which is made up of stone materials. As a result, water level difference occurs between inside and outside of the embankment by seepage through the stone materials and causes an uplift pressure acting on the impermeable sheet when the water level inside the embankment is low. Although raising the water level inside the embankment using water pumps is seen as a countermeasure, determination of the coefficient of permeability of the stone materials necessary for determining the number of pumps becomes an issue. In previous studies, laboratory experiments were conducted using small stone particles, however, experiments using actual particle size found in the site were not conducted. In this study, permeability experiments are conducted using stone particles similar to that found in the site and applicability of the Dupuit-Forchheimer Law is studied through comparison with experimental results. Results of the experiments show that the Dupuit-Forchheimer Law is applicable even for larger particle size. Furthermore, comparison of field observation data with calculation results also shows the applicability of the Dupuit-Forchheimer Law even for stone materials with real scale particle size.

 Centrifuge model tests were carried out to investigate the behavior of suction anchors in saturated fine sandy deposits subjected to cyclic loading, in view of their use in mooring foundations for floating offshore wind turbines. Monotonic or cyclic pullout forces were applied to the wire line connected to the side wall of the cylindrical anchor. The initial pullout angles of elevation were between 15 to 25 degrees. Holding capacities obtained from monotonic pullout experiments were compared with those calculated by Deng and Carter method developed for anchors with the embedment to diameter ratio not less than unity, in order to study the applicability of the workable method to shorter anchors. The calculated capacities underestimated the measured ones by about 30 % in this study with the anchor of embedment to diameter ratio of about 0.8. In a cyclic pullout test with large amplitude of wire tension, where the tension periodically reduced to zero, we observed remarkable evolution of pullout displacement of the anchor.

 Local subsidence damage on the airport taxiway right over the ground nearby the underground structure occurred during the 2011 off the Pacific coast of Tohoku Earthquake. The authors consider that local subsidence is due to the dynamic interaction between the ground and underground structures, and are investigating the mechanism of ground surface subsidence. From the results of shake table tests of a large model in 1g gravitational field in which an underground structure model was installed in a sand ground, the relationship between the accumulated shear strain of the ground and the amount of ground subsidence caused by the dynamic interaction between the ground and the underground structure has been demonstrated. In this study, as a fundamental study of numerical analysis, we focused on strain history evaluated in shake table tests, compared the analysis results of effective stress and total stress truly nonlinear analyses, and evaluated the evaluation method of strain history of the ground.

 A simulation method has been developed to predict the settlement and accumulation process of rubble from a barge with high accuracy and in a short time, based on the coupled CFD-DEM analysis. Although this method treats the stones as spherical particles, by modifying the drag coefficient and introducing a new lift model, the hydrodynamic properties of the irregularly shaped stones are reproduced. The angle of repose during accumulation is also reproduced by taking into account the rolling resistance of the particles. In addition, the computation time can be significantly reduced by replacing the accumulated particles with planes for each discharge. The validity of this analysis method was confirmed by comparing the settling behavior and the shape of accumulation with the model experiment.

 This study aims at proposing a new prediction expression of time-related deterioration of tensile strength for silt curtains. The prediction expression of the present design method is based on 315 real data regarding tensile strength deterioration for silt curtains such as field experiments results and the application was limited to around 1,000 days of expected total period a silt curtain would be equipped.

 Authors proposed the new prediction expression for time-related tensile strength deterioration based on statistical analysis using collected 500 real data and expanded its application limit to around 1,800 days.

 In this study, underwater acoustic experiments are conducted with water tank to obtain basic knowledge that contributes to the technology for reducing pile-driving noise by hydraulic hammer. In this experiment, prior to testing the applicability in the actual sea area, simulated pile-driving is carried out in two types of test tanks (volume: 1.0 m³, 450 m³). In a small tank, φ46.8 mm steel pipe is hit with various noise reduction measures in combination, and the noise reduction effect in the water is evaluated. In a large tank, the effects of countermeasures determined from the results of small tank test are measured using φ250 mm steel pipe. As a result, it is confirmed that the sound pressure level is significantly reduced by the bubble curtain, bubble sleeve, and the combination of submerged mound and bubble curtain. In addition, the frequency band to be reduced tended to be different depending on the countermeasures.

 When high waves caused by the typhoon act on the rubble dike during construction, the rubble mound could be damaged. That is one of serious problems in the field. Therefore, it is necessary to propose countermeasures to reduce the damages of the rubble mound during construction. From the investigation of the damage area, the submerged depth of mound was deformed to about 1.2 times the significant wave height of the incident wave. The net was installed inside the area as a measure to reduce damages, and both ends were held with stone baskets. The net was made of fiber and wire mesh with different flexibility, but there was no difference in effect depending on the material. The amount of stones flowing out of the design section was evaluated as the damage rate. As a result, the amount of stones flowing out was reduced to less than 1/2. The proposed measures to reduce the damages have obtained good results. Applicability to the field can be sufficiently achieved by selecting a net with high durability. This method could be expected to be applied to the field.

 We have devised the on-site reforming method with a ground improvement ship to improve a seabed clay ground by mixing steelmaking slag at the original position. In order to improve the mixability of the clay with water content close to the liquid limit, we have improved mixing equipment in the bucket attached to the ship. As a result of experiments on a 1/5 scale model to evaluate effectiveness of improved mixing equipment, the improved equipment was found to be able to disperse slag evenly in the clay in a shorter mixing time than the conventional equipment. Moreover, for clay with a water content of 1.1 times or more the liquid limit, the variation in strength of improved clays was reduced to the same level as clay with a high water content. However, in the case of clay ground where the natural water content is below the liquid limit, it is necessary to extend the mixing time or to add water to the clay in the bucket.

 Utilization of BIM/CIM is becoming active in port construction. The system is to provide information to the workers and engineers through a large display and a tablet to confirm the construction methods and to examine the construction procedures. The advantage of BIM/CIM is that it is possible to find defects and hazardous locations by pre-construction simulations.

 It is considered that there is a small difference between the BIM/CIM models and the above-mentioned confirmation methods, the more these things can be discovered and improved. Here, the above-mentioned improvement activities were carried out by VR using BIM/CIM data, and the development method used at that time was shown. Besides, we have summarized the model layout and the objects necessary for virtual space that reduces the deviation from the reality in the actual implementation in the field. Moreover, the issues discovered from these are shown.

 Water pressure due to penetrating waves from the open sea, tide level propagation, or water level differences between the inside and outside before the final deadline is applied to the liner sheet in the controlled sea-based disposal site. When welding on the sea surface or curing during wintering is necessary, stability against the flow due to strong winds is also important. The study site has severe winds and waves in the winter, so it is necessary to cure the liner sheet during winter, and use a five-layer integrated liner sheet that has not been used in the whole surface impermeable works.

 The purpose of this study was to (1) examine the method of curing the liner sheet during wintering by observing the water level and flow in the water area in the disposal site, and (2) confirm the basic performance when the 5-layer integrated liner sheet was laid.

 When we construct the breakwater using dredged soil improved with converter slag, it’s important to manage the prevention of pollution, the quality control of improved soil strength, the stability of the improved soil against waves. In this study, we determined the relationship between Suspended Solids (SS) and the mixing rate of converter slag, the strength of improved soil and integrated temperature in the curing period. We also studied the critical friction velocity against waves, the defect rate and the coefficient of variation of the strength of improved soil with converter slag.

 Recently, the introduction of precast concrete to the port pier is progressing in order to improve productivity. When the precast method is applied to the upper concrete of port pier, it is common to weld the main reinforcement and steel pipe piles by field welding in order to transmit the moment. The authors propose a new connection structure of pile top using loop joint which eliminates field welding and minimizes cast-in-place concrete. In this study, tensile tests for small specimens and reversed cyclic bending tests for beams were performed for practical application of this method and establishment of design method. The present result suggested that the strength of the loop can be evaluated by considering the decrease in strength by 20% in the existing Leonhardt’s equation. Furthermore, it suggested that beams joined by separate loop joints have the same strength as continuous double reinforcement without loops even under the conditions where positive and negative bending are repeatedly applied.

 In order to predict sedimentary profile of blocks with high accuracy, a calculation method based on the motion of each individual concrete block was proposed. The properties of the blocks in the sedimentation process were investigated and this was given as an initial condition for the behavior analysis of the blocks. The numerical analysis of the translation and rotation of each individual block was conducted using a physics engine, and the validity of these results was confirmed. Finally, prediction of the sedimentary profile on rubble mound has been conducted using proposed method.

 Inspection of the underwater part of fishing port facilities is mainly conducted by visual inspection by divers. For this reason, the results of visual inspection tend to vary depending on the skill of the diver and often lack objectivity. In this paper, in order to improve the inspection method of the underwater part, we focused on the underwater 3D scanner that can observe the deformation of the underwater part of the facility in detail, and examined the inspection method using the underwater 3D scanner.The main results are as follows. (1) Movement and scattering of the covering blocks and damage to the steel structure were accurately observed. (2) It was possible to observe near the water surface of the facility where environmental changes were large and deterioration was likely to progress.

 The Tokyo Bay coastal area is vulnerable to storm surges. For this reason, the Tokyo Metropolitan Government has constructed the tide embankment along the coast to prevent seawater from entering the inland. In the past, the validity of the crest height on the tide embankment has been examined numerically based on a model typhoon by several researchers, and it has been pointed out that the crest height is insufficient. In this study, the validity of the crest height was discussed based on the trend of past statistical data on weather and sea conditions. Also, we confirmed from the field investigations of the existing tide embankment and mentioned the method to renovate the tide embankment due to insufficient height. And, we indicated that raising the crest height was appropriate for renovation. Then, we proposed a method of raising the crest height in the renovation considering usual landscape.

 The abrasion process of block masonry seawall constructed on a gravel coast was investigated by field observation data. The movement characteristics of 50 kg rough stones due to wave action were disclosed by hydraulic experiments with a model scale of 1/25. The relationship between the wave height and the number of collisions was shown for three wave periods and four water level conditions. It was revealed that the movement of rough stones was the most significant when the still water level was the same as the top surface of rough stones. It was also found that the number of collisions increased with the increase in periods. The moving speed of rough stones was based on the result of video analysis on the stone movement pattern due to wave action. The characteristics of overtopping waves were investigated by hydraulic experiments with a model scale of 1/35. The abrasion rate of the block masonry seawall was estimated by the existing experimental formula using observed wave and tidal data at the nearest NOWPHAS station. The estimated abrasion rate was nearly the same as the observed value. Furthermore, a repairing method was proposed for the damaged block masonry seawall based on the results of the wave overtopping test.

 Haneda Airport D-runway is a hybrid-type offshore airport consisting of the reclaimed area and the piled-elevated platform. Because the D-runway is composed of different structures, expansion joints are installed to absorb the relative displacement between these structures caused by temperature variations and earthquakes. In this paper, the behavior of expansion joints called rolling-leaf joints installed in the runway and taxiway on which the aircrafts run is investigated by the temperature change measured for 10 years after operation and the 2011 off the Pacific coast of Tohoku Earthquake.

 The D-runway at the Haneda airport has a hybrid structure consisting of land reclamation and pier sections. In addition to the settlement, the horizontal displacement of the reclamation needs to be evaluated to secure the stability of the steel pipe sheet-pile cellular seawall at the connection of the two sections. For such purpose, soil/water coupled FE analysis with elasto-viscoplastic model has been used throughout the design, construction and operation. During the construction, the FE analysis was compared to the field observation and the material parameters were updated to enhance the accuracy. Meanwhile, the construction plan was justified/modified based on the prediction of the FE analysis. This paper reports the results of the field measurement and the deformation analysis during the construction and the past 10 years of operation. The long-term prediction for the future operation is also described.

 To corrosion protection in marine steel structures, cathodic protection methods is applied to the under-seawater area, and coating protection methods is applied above the tidal zone. Therefore, we considered to expand the effective range of cathodic protection in under-seawater to the coating protection area by apply high-conductivity mortar mixed with carbon as a coating material. Compared to ordinary concrete, it can reduce the resistance to 1/100 and confirmed that it can be protected with 0.1 µA/cm² corrosion protection current in underwater environment and 20 µA/cm² in dry environment. At the time of two years of exposure, sufficient anticorrosion performance was confirmed at a depth of L.W.L+160 cm or less.