Annual Report
2021
Port and Airport Research Institute Annual Report 2021

Message from the Director General

Message from the Director General

Creating Port and Airport
Technologies That Contributeto the World
港湾空港技術研究所長（うみそら研理事）

髙野誠紀Seiki TAKANO
Director General, Port and Airport Research Institute(Executive Director, National Institute of Maritime, Port and Aviation Technology “Umisora Institute”)

In April 2016, three research institutes – the National Maritime Research Institute (NMRI), the Port and Airport Research Institute (PARI), and theElectronic Navigation Research Institute (ENRI) – were integrated, the National Institute of Maritime, Port and Aviation Technology (MPAT), (commonly known as “Umisora Institute.”) was launched. We, the Port and Airport Research Institute (PARI), are going to play a role in the Umisora
Institute as a research institute responsible for survey, research and technological development related to the maintenance of ports and airports,
while inheriting our past steps. Our predecessor institute, the Port and Harbor Research Institute (PHRI) of the Ministry of Transport (MOT) has been
supporting technically numerous port and airport projects such as Kashima Port development, and Haneda/Kansai International Airport construction since its birth in 1962, and has achieved research results that are highly evaluated worldwide. We, the Port and Airport Research Institute willfurther expand, deepen the cooperation and integration of research in different fields by the cooperation with other two integrated institutes (NMRI
and ENRI), and maximize the results of research and development by demonstrating the synergistic effect, in addition to the close cooperation with
the National Institute for Land and Infrastructure Management (NILIM), Ministry of Land, Infrastructure, Transport and Tourism (MLIT) from now on.
This annual report summarizes the results for FY2020, the fifth year of the first medium- to long-term plan (FY2016 to FY2022).
In the first medium-to long-term plan, we will focus on the four R & D issues; "Coastal Disaster Mitigation and Restoration", "Formation of
Infrastructure for Vigorous Economy and Society", "Preservation of Marine Interests and Utilization of Oceans", and "Creation and Utilizationof Coastal Environment".
In "Coastal Disaster Mitigation and Restoration", we are proceeding research of a development of predicting method of strong vibrations
near the epicenter, Tsunami predicting techniques based on combined observation information, a method for estimating the amount of local
scour structures caused by Tsunamis.
In "Formation of Infrastructure for Vigorous Economy and Society", we are proceeding research is being conducted on the introductionof ICT into container terminals, the improvement and development of inspection equipment for offshore structures, and the development ofcore-less ground survey methods.
In "Preservation of Marine Interests and Utilization of Oceans", we are proceeding research on analysis methods for topographic dynamics on isolated islands, methods for discriminating the distribution and use of reef-building organisms, and clarification of horizontal resistance characteristics of pile foundations for offshore wind power generation facilities.
In "Creation and Utilization of Coastal Environment", we are proceeding research, such as quantification of blue carbon (mitigation effect)in various coastal areas and practical application of carbon offsetting, the influence of the super-moon on coastal topographical changes.
In carrying out these researches mentioned above, we will be pursing the two major mottos of our institute, “The Research level is the highest in the world” and “The Research results are useful the actual projects”. We will be also promoting strategic international activities such as
contributing to the overseas expansion of infrastructure promoted by the national government and technical support to overseas countries.
Furthermore, in order to respond to technical issues across research fields, PARI internally set up five centers (International Research Center for
Coastal Disasters”, “Life Cycle Management Research Center”, “Ocean Infrastructure and Offshore Wind Energy Research Center”, “Productivity Improvement Center”, and “ Innovation Promotion Center”), and we will be further strengthening cooperation with the Regional Development
Bureaus of the Ministry of Land, Infrastructure, Transport and Tourism, which have technology implementation sites, and private companies.
In recent years, natural disasters such as earthquakes, storm surges, and high waves have intensified, occurred frequently, and the acceleration and deepening of National Resilience is an urgent issue. In view of the uniqueness of our institute as research institute that conducts
practical research and development closely related to the field under the harsh natural conditions unique to Japan, we will be continuing toutilize the knowledge and human resources of our institute, in addition, we would like to firmly work on emergency response and support for
restoration in the event of natural disaster, enlightenment related to disaster prevention.
We would greatly appreciate your continued understanding and support.

CONTENTS
12345

Outline of Organization

02p

Management Strategy

03p

Structure of Research Themes in FY 202004p

Research Themes and Activities in FY 2020

05p

Fundamental and Exploratory Research

14p

01 PARI Annual Report 2021

6
7
8
9

Published Research Papers

19p

The Open Institute

20p

Outstanding Research Activities

21p

PARI Events

22p

Outline of Organization
Administrative Staff and Researchers, and Budget

1

Administrative staff
18

Researchers(Others)
42

Commissioned research income, etc.
1,823 million yen

Researchers(with PhD)
44
As of April 1, 2021 (In Yokosuka)

Operational subsidies
1,223 million yen* The graph above shows the budget for technical fields related to ports,
waterways, coasts, and airports.

Organizational Structure
Auditors

President

National Institute of Maritime,
Port and Aviation Technology (MPAT)

Vice Presidents
Distinguished
Researchers

Strategic Planning andManagement Office(In Yokosuka)

Administration Department

Planning Department

Administrative Coordination andDisaster Prevention Department

Director for Research Planning
Director for Promotion of Intellectual Property Utilization
Administrative Division

National Maritime
Research Institute(NMRI)

Port and Airport
Research Institute(PARI)

Electronic Navigation
Research Institute(ENRI)(In Yokosuka)

Planning, Coordination and Disaster Prevention Division
Facilities Division
Wave Group

Coastal Hydraulic Engineering Department

Maritime Structures Group
Tsunami and Storm Surge Group

Coastal and Ocean Development Department
Coastal and Estuarine Environment Department

Geotechnical Engineering Department

Senior Director forInternational Affairs
Senior Director for Research

Marine Information Group

Coastal and Estuarine Environment Group
Coastal and Estuarine Sediment Dynamics Group
Soil Mechanics and Geo-Environment Group

Fellow
Managing Director for
Research Affairs

Coastal and Ocean Development Group

Soil Dynamics Group

Soil Stabilization Group
Foundations Group

Earthquake Disaster Prevention Engineering Department

Engineering Seismology Group
Earthquake and Structural Dynamics Group
Structural Mechanics Group

Structural Engineering Department

Materials Group
Frontier Technologies for Structures Group

Infrastructure Digital Transformation
Engineering Department

Marine Environment Control System Department

Big Data Technology Group
Meta-Robotics Group
Cyber Construction Technology Group
Marine Pollution Management Group
Marine Environmental Information GroupInternational Research Center for Coastal Disasters Reorganized on April 1, 2017
Life Cycle Management Research Center

Reorganized on April 1, 2013

Ocean Infrastructure and Offshore Wind Energy Reorganized on October 1, 2017
Research Center
Productivity Improvement Research Center
Innovation Promotion Center

Established on April 1, 2017
Established on February 1, 2020

As of July 1, 2021

PARI Annual Report 2021 02

Outline of Organization

FY 2021
Annual Budget
3,046 million yen

Total
104

Management Strategy

2Management Strategy

Mid- and Long-Term Objectives(FY 2016 to FY 2022)

Mid- and Long-Term Plans(FY 2016 to FY 2022)

The Minister of Land, Infrastructure, Transport and Tourism(MLIT) sets mid- and long-term business goals for the National Research and Development Agency, National Instituteof Maritime, Port and Aviation Technology to achieve. These
goals stipulate our operations as follows.

The MLIT sets mid- and long-term goals. In response tosuch goals, MPAT sets mid- and long-term plans to achieve
the goals. Among such plans, important points in maximizing
research and development results and improving the qualityof other projects are outlined below.

Basic Policies for Structural Reform of Independent Administrative Institutions were decided in a Cabinet decisionon December 24, 2013 (hereafter called “Basic Policies for
Reform”). Based on these policies, the National Maritime
Research Institute (NMRI), Port and Airport Research Institute (PARI), and Electronic Navigation Research Institute(ENRI), which were National Research and Development
Agencies operated under the jurisdiction of the MLIT, were
integrated into the National Institute of Maritime, Port andAviation Technology (hereafter called “MPAT”) to implement the policies.
Article 2, paragraph 1 of the Act on General Rules stipulates as follows: some clerical tasks and business require
sound implementation from the viewpoint of general welfare including stabilization of people’s life and socioeconomy, but at the same time do not require government-led
implementation. Some of these clerical tasks and businesses face the risk of neglect when their operation is
entrusted to private entities, so MPAT was established toeffectively and efficiently conduct their operation.
In consideration of the previous roles of each institute,
MPAT is required to continue to make full use of its accumulated wealth of knowledge and stature, and to proceedwith research and development according to the Basic
Policies for Reform. In addition, MPAT will constantly review research contents and select research areas to address changes in the social environment. At the same time,
MPAT will more actively engage in research and development activities to solve policy challenges in each field,
such as conducting research in emerging fields.
MPAT has promoted research and development in eachfield, cultivated technological seeds, and accumulated
specialized knowledge. Thanks to MPAT’s legacy, such
multidisciplinary research became viable. In considerationof this background, MPAT will efficiently and effectively
implement multidisciplinary research including “Promoting
the protection of maritime interests and the utilization andapplication of marine-resource/marine-renewable-energy
development and other projects”. Through such implementation, MPAT will help put national policies into practice.
Furthermore, MPAT considers that it is important toreturn the benefits achieved through research and development to society, as well as to cooperate with external
institutes and to widely disseminate research results. In
addition, MPAT is committed to strategically implementing international activities as follows: active participationin projects to formulate international criteria and standards; international promotion of Japanese technologies
and systems through international cooperation; and otheractivities.
As outlined above, MPAT’s missions are based on the
MLIT’s Basic Plan for putting MLIT-recommended policies into practice. Today, Japan faces various important
challenges. By realizing these policies, we can solve suchchallenges.

1. Promotion of multidisciplinary research and other activities
MPAT will efficiently and effectively implement multidisciplinary research spanning research fields of the three pre-integration institutions to contribute to putting the following policies into practice: promotion of ocean utilization, enforcementof international industrial competitiveness, and other policies.

03 PARI Annual Report 2021

2. Research and development of technologies associated withports, water ways, coasts, and airports and other activities
MPAT will focus on the research and development challenges detailed in the following pages, to devise the following
MLIT-recommended initiatives: disaster-prevention and disaster-reduction countermeasures for port and airport facilities;
countermeasures for facility obsolescence of existing structures; and initiatives to create maritime-development hubs.
Among basic research, MPAT also actively engages in research to understand the mechanisms of ocean waves andbeach transformation and principles and phenomena regarding the dynamic behavior of the ground and structures.
MPAT also uses its foresight and flexibility to accurately
address emerging research which might lead to new research results.
3. Returning benefits from research and development results
to society
MPAT will try to resolve technological policy challenges, toaddress disasters and accidents, to enforce bridging functions, to promote and utilize intellectual property right, andto enhance the transmission of information and publication.
4. Promotion of strategic international activities
MPAT will contribute to international standardization andcooperate with overseas institutions.

MPAT Operation Management
MPAT will focus on rapid decision-making to engage instrategic institutional operations.
MPAT will also hold the following meetings for multi-faceted investigation of various operational agendas from a broad
perspective:
1. Management strategy meetings: In-house meetings formaking decisions on important issues related to the core
principles of MPAT management
2. Board of Directors meetings: Weekly meetings involving all
executives and division managers as well as the three directors of the Administrative, Coordination and Disaster Prevention Department
3. Board of Councilors meetings: Meetings to gather insightsfrom independent experts who have broad and deep knowledge
4. External Evaluation Board: An external body in which third
parties objectively and technically evaluate MPAT’s research

Structure of Research Themes in FY 2020
Research
Field

Research Theme

Research Subtheme① Research on strong ground motions
and damage predictions in the case of thegreatest earthquakes

Strong motion earthquake observation in port and airport area

Fundamental Research

Investigation of earthquake disaster

Fundamental Research

Development of estimation method for near-fault strong ground motions

Fundamental Research② Research on damage-reduction
techniques against the greatest
earthquakes

Applied Research③ Research on the interaction ofearthquakes, tsunamis, and high waves
with ground dynamics

Applied Research① Research on ICT-based decision
support systems② Research on the development oftsunami-resistant ports

Development of a new method for predicting liquefaction-induced ground subsidence and flow☆

Applied Research

Development of countermeasures for early exhibition of seismic performance of coastal facilities☆

Fundamental Research
Development Research② Research on the technology to reduce
maximum storm surge and wave disasters

2. Formation of Infrastructure for Vigorous Economy andSociety

2A Research on① Research and development forEnhancement of Port andenhancing the operations of ports,
Airport Performance forharbors, and airports
Industrial Competitiveness

2B Research on Life
Cycle Management ofInfrastructures① Research on technologies forprolonging the life of infrastructure

Development of multi-observation based tsunami forecasting method

Fundamental Research

Development of the estimation method for local scour around coastal structures due to tsunami

Development Research

Application of the particle method to the large deformation of port structures due to tsunami
Elucidation of oceanographic phenomena based on central processing and analysis of observation
data
Identification of issues and improvement of wave estimation methods applicable to Japan’s coastal
areas
Development of a pier inundation simulation method that considers seawall overtopping anddrainage

2C Research on
Effective Use of Existing
Infrastructure Facilities

Fundamental Research
Development Research
Applied Research
Applied Research

Assessment of possible maximum storm surge hazard by using storm-surge-wave coupled model☆

Applied Research

Proposal of planning method for automated container terminal by quantitative numerical simulation

Applied Research

Proposal of new technology for container terminal operations

Fundamental Research

Evaluation of longterm durability of concrete, steel and various materials based on exposure test

Fundamental Research

Development of the performance evaluation method in protective coating for marine structures

Fundamental Research

Evaluation of applicability of sustainable materials in the marine environment

Applied Research① Research on techniques to improve or
renew existing facilities② Research on effective use andtechniques of treating construction
byproducts

3. Preservation of Marine Interests andUtilization of Oceans① Study on the preservation and use of
remote islands

Study of the effects of steel mesh in concrete pavement used at airports from the design andimplementation perspectives☆ Examination of productivity improvement methods applicable to concrete structures at ports

Fundamental Research

Study on application of inspection and diagnosis systems for improvement of performance
evaluation of marine structures

Development Research

Development of adaptive technique for inspection vehicle to disturbance in operation

Applied Research

Development of quality evaluation method for ground improvement using geophysical exploration

Fundamental Research

Study on process leading to rupture of pier structure for high definition of performance regulation

Applied Research

Effect of defective part of solidified body on its internal stability

Fundamental Research

Basic research to develop coreless ground survey methods and establish digital geotechnicalengineering

Development Research

Development of fender system for automatic ship berthing/unberthing

Fundamental Research☆ Development of analytical methods for the topographic dynamics of carbonate islands
Study on the multi-functional evolution of underwater construction machinery using machineguidance techniques

Development Research
3A Research on
Development andUtilization of Oceans

Development Research

4. C reation and Utilization of Coastal
Environment① Research on coastal-ecosystemutilization③ Research on countermeasuretechnologies against sea oil spill
4B Research on Coastal
and Estuarine Processes① Research on coastal protection andmaintenance of waterways and mooringbasinsResearch on the estimation method of wave force acting on offshore wind power facilities☆

Elucidation of the horizontal resistance characteristics of pile foundations for offshore wind power
plants under various fluctuating loads

Applied Research

Research on load setting method for offshore wind power facilities under waves and winds

Fundamental Research☆ Evaluation of the mechanical properties and durability of infrastructure materials in the deep sea

Fundamental Research☆

Applied Research
Fundamental Research② Research on the water-environment
simulation and analysis in inner-bay

Study on floating breakwater equipped with wave power generation device

Applied Research
Fundamental Research

4A Research on
Enhancement andUtilization of Coastal
Ecology☆ Study on the application of acoustic imaging system to ICT-based construction projects

Applied Research② Research on infrastructure technology
for utilization and development of oceans

Study on wave forces on the structural members of protective facilities under storm surges, highwaves, and tsunami
Proposal of evaluation method to estimate the productivity of the container terminal system
introduced AI and ICT technology or other method

Applied Research

Applied Research② Research on systems for inspecting
and diagnosing infrastructure

Stability evaluation of offshore structures against washout, cavity formation, etc. and developmentof countermeasure techniques
Evaluation of the deformation and fracture characteristics of coastal soil structures in relation to
waves and flows, and development of reinforcement technology
Development of a 3-dimensional simulation model for drift behavior and its application to a
2-dimensional simulation model

Development Research

Fundamental Research① Research on storm surge, wave and
1C Research on Mitigation maximum damage estimation
and Restoration of Storm
Surge and Wave Disasters

Development of seismic performance evaluation method for offshore wind turbines and coastal
structures against the largest earthquake motions

Validation of the newly developed global dynamic model for the projection of atmospheric CO2
uptake rate and inundation control in shallow coastal ecosystems
Coastal geotechnical/geomorphological design for disaster mitigation and ecological environment☆ Cross-sectional observation and analysis of atmospheric and oceanographic issues at bay mouths

Fundamental Research

Numerical study on responses of aquatic ecosystem to an environmental change

Fundamental Research

Development of the methods for increasing ecosystem functions in eelgrass meadow

Applied Research

Numerical analysis of coastal current by numerical simulation and data assimilation

Development Research

Development of oil spill response technology for next generation

Fundamental Research

Observation of coastal phenomena at HORS and development of numerical simulation of
topography change for port and surrounding beaches

Fundamental Research
Fundamental Research

Developing future projection model of coastal change in the context of climate change☆ Development of sediment transport control method to minimize harbor siltation* Special research involves high-priority research topics on which PARI must conduct studies intensively. PARI allocates significant human resources and funding to these projects, and also arranges crossfunctional research systems extending beyond the basic organizational structure within PARI as needed, in order to accelerate research.

PARI Annual Report 2021 04

Structure of Research Themes in FY 2020

1B Research on Mitigation
and Restoration of Tsunami
Disasters

Fundamental Research3

1. Coastal Disaster Mitigation and Restoration

1A Research on Mitigationof and Restoration from
Earthquake Disasters

Item on the Research Agenda(☆indicates special research*)

Type of ResearchResearch Themes and Activities in FY 2020

1A

Research on Mitigation of and Restoration from Earthquake Disasters

Background and Objectives

4
Research Themes and Activities in FY 2020

In the event of large-scale disasters including Nankai megathrustearthquakes and earthquakes in the greater Tokyo area, it is required
to secure necessary trunk line cargo transportation soon after an earthquake and to quickly secure the requisite minimum transportation of key
emergency supplies for recovery and reconstruction. In addition, theinteraction of earthquakes, tsunamis, and high waves with the groundmight cause coastal disasters, so it is necessary to reduce such risks.
Therefore, this research aims to develop reliable techniques for predicting seismic motions and damage to structures caused by the strongest, long-duration earthquakes. The research also intends to develop
new techniques for reinforcing existing structures for improving theiranti-seismic capacity, assessing damage during on-site damage surveys, and implementing emergency measures. In addition, the researchattempts to elucidate the phenomenon of tsunami caused by submarine landslides, explain soil performance under the effects of tsunami,high waves, and flows, and identify related countermeasures.

Research on damage-reduction techniques against the greatest
earthquakes
We worked on the development of a technique for assessing the seismic performance of offshore wind turbines and coastal structures, andexamined techniques that could be implemented to swiftly activate theseismic performance of coastal facilities in the greatest earthquakes.
In particular, we used the earthquake response analysis program thatwas previously developed for use on offshore wind turbines to perform
a number of analyses on monopile foundations, and examined the effect of simultaneous action of seismic motions and wind, the effect of
the liquefied layer modeling method, and the effect of seabed sloping.
Furthermore, we conducted shake table tests and analyses on a seismic reinforcement method that could be applied to vertical-pile wharves
that would involve installing additional structural members, and confirmed that the method could reduce the amount of damage and deformation for the overall wharf structures by allowing damage to theadditional structural members.

Research Topics

Research on the interaction of earthquakes, tsunamis, and highwaves with ground dynamics
Concerning the interaction of earthquakes, tsunamis, and high waves
with ground dynamics, we worked on the development of a stability
analysis for washout, cavity formation, etc. affecting coastal structures,and examined possible countermeasures. We also worked on techniques for evaluating the deformation and failure of coastal geotechnical structures under wave and flow forces and investigated possible
measures for reinforcement.

Research and development comprise the following subthemes for
mitigating earthquake damage and facilitating post-disaster recovery:① Research on strong ground motions and damage predictions in
the case of the greatest earthquakes
We will develop a composite source model for simulating near-source
strong ground motions that can consider not only the strong groundmotions that are caused by the rupture of deep asperities, which have
conventionally been reflected in structural designs, but also the effectsof shallow slip as observed during the Kumamoto earthquake, and will
examine its validity.
② Research on damage-reduction techniques against the greatest
earthquakes
We will develop techniques that will swiftly activate the functions ofcoastal facilities following earthquakes that involve adding new components to existing facilities and replacing those when damaged byearthquakes.
③ Research on the interaction of earthquakes, tsunamis, and highwaves with ground dynamics
We will develop effective design and countermeasure techniques for
mitigating washout, cavity formation, etc. that occur to coastal structures under various dynamic external forces.

Activities in FY 2020

Research on strong ground motions and damage predictions in thecase of the greatest earthquakes
In order to predict seismic motions and damage in the greatest earthquakes, we observed strong ground motions in ports and airports andorganized and analyzed their data, investigated earthquake disasters
and their causal factors, and worked on the development of novel methods for predicting near-source strong ground motions and liquefactioninduced ground subsidence and flow. In particular, to develop a method
for predicting near-source strong ground motions, we conducted fundamental research on fault plane discretization and use of complex frequency to calculate the effects of shallow slip with improved accuracy
in order to develop a composite source model that can consider not
only the strong ground motions that are caused by the rupture of deep
asperities, which have conventionally been reflected in structural designs, but also the effects of shallow slip. We also developed a composite source model applicable to actual earthquakes and verified its validity by comparing the simulated ground motions with the observed ones.

05 PARI Annual Report 2021

Simulated ground motions with the composite source modelfor the Kumamoto earthquake
Black indicates observed ground motions while green andred indicate simulated ground motions

Research
Research
Themes
Themesand and
Activities
Activities
in FY
in2020FY 2020

1B

Research on Mitigation and Restoration of Tsunami Disasters

Background and Objectives• The optimization function used to estimate the tsunami source faults
has multiple local peaks, which makes it difficult to find the global
optimal solution. We developed an inversion method using the replica
exchange Markov Monte Carlo method to overcome this problem.

Reversepropagation
analysis

ine
al l
ast
Co

GPS wave buoys

Optimization function with local
peaks (illustration of 1-D crosssection with a 9-D function)
UpliftOcean radar

Subsidence

Research and development on this theme cover the following topics
for tsunami disaster mitigation and recovery:• For our research on simulation model for tsunami drift object , we are
examining the accuracy of developing 3-D simulation model for the
behavior of drift object.
• For our research on multi-observation-based tsunami forecast, weare verifying the efficacy of our prediction method utilizing tsunamisource inversion.
• For our research on the application of particle methods to the deformation of port structures, we developed new boundary models formore accurate and easy simulations.

Activities in FY 2020

• We developed a 3-D model to estimate the behavior of the drift object
on quay walls, and compared the simulation results of the planar 2-D
and 3-D models. We found that the behavior of drift object significantly changes by the rotational movement in 3-D and the contact
with the ground surface, which the planar 2-D model was unable totake into account.

Tsunami-source fault estimated from multiple-point observation data

• We elucidated the process of how a tsunami goes under at the headof a breakwater, increases in velocity near the seafloor, and causes
scouring, through model experiments and numerical calculations.
Related to this, we identified a set of effective methods for calculating wave forces acting on breakwaters, and verified the stabilityof a novel scour-suppressing engineering technique, etc. utilizing
connected stone filled fibernet. These research findings
were used in the design ofthe breakwaters built near
the mouth of Urado Bay,and patents were obtainedon the scour-suppression
engineering method. We
also elucidated the processof how a tsunami-induced
swirl could entrap a human
body, as well as the buoyan- Scour suppression by installation of concy necessary for suppress- nected stone filled fiber net
ing such entrapment.
Difference between
bottom water velocity
and cross-sectionalmean velocity

Height [m]Cross-sectional meanwater velocity① Early stage of entrapment t = 0.0 s② t = 0.5 s

Structures

Height [m]Time = 8.00 [s]Numerical simulation by 3-D modelCalculation of water velocity at the breakwater head

Entrapment by tsunami• We have developed a free-surface boundary model for the particle
methods. This model can appropriately treat unphysical voids generated inside the water under the wave breaking, which are inevitably
given in the single phase flow simulations by the N-S solvers. In addition, a new wave generation model has been developed for moreeasy setups of wave boundaries including connection to other planar
2-D simulations. This model works at any given uniform depth but
also along a slope facilitating wave deformations. Hence, the method
is expected to drastically improve the computation efficiency by focusing its computation area around the target structure.

PARI Annual Report 2021 06

Research Themes and Activities in FY 2020

Multiple observation data
Estimated fault

Research Topics

4

Since the Great East Japan Earthquake in 2011, we have studied
stable structures against tsunami overflows and developed a numericalsimulation model to predict the drifting of debris generated by the destruction of buildings. However, complex behaviors of tsunami run-up
on land and the resulting damages are not fully understood and modeled
yet. In addition, regarding a technique for real-time inundation forecast,which is expected to be utilized for evacuation and other purposes, only
data from GPS wave buoys is used; other valuable data is not fully utilized yet. Therefore, we are aimed for changing disaster prevention andreduction countermeasures into a pre-disaster stage from post-disasterone, and will conduct research to establish resilient coastal zones which
can withstand the most severe tsunamis, i.e., to protect lives against themost severe tsunami, to avoid catastrophic socioeconomic damages,
and to enable early recovery and reconstruction.

Research Themes and Activities in FY 2020
Research on Mitigation and Restoration of Storm Surge and Wave Disasters

Background and Objectives

4

Research Topics

Research and development on the theme of mitigation of disasters
caused by storm surges and high waves and disaster recovery cover
the following topics:• For our research to elucidate the oceanographic phenomena basedon ocean observation data, we are continuously processing and analyzing wave observation data (processing of quick reported and finalized wave data, and analysis of wave statistics).
• For our research on the simulation of inundation caused by waves
within ports, we are developing an inundation and drainage model toaddress the issue of waves overtopping on quay walls.
• For our research on storm surge hazards of the highest magnitude,
we are working on storm surge and inundation calculations that take
into account the effects of waves, while reviewing sea surface dragcoefficients under ultra-high-velocity wind conditions.
• For our research on the wave forces acting on the structural membersof protective facilities under storm surges, high waves, and tsunami,
we are examining methods of estimating chronological changes inwave forces and also the dynamic behavior of the structural members and the ground using neural networks, etc.

• The improved version of NOWT-PARI, which can perform continuous
calculations while reflecting the chronological changes in storm surges and high waves, was tested to verify its ability to monitor the inundation process of wharves, which also factored in the natural drainage
caused by lowered tidal levels and decreased overtopping waves. As
a result, we were also able to confirm the reproducibility of the wharf
inundation that occurred in Kobe Port during Typhoon Jebi (2018).

Process of inundation caused by storm surges and high waves during Typhoon Jebi (2018)• Storm surge simulations considering wave setup were conducted
to reproduce the observation data of sea level deviation caused bytyphoon Jebi. The effect of typhoon translation speed on the storm
surge deviation and the method of setting the sea surface drag coefficient at high wind speed are investigated.
• In view of the disaster that occurred in Yokohama Port during Typhoon Faxai, we conducted a large hydraulic model experiment andperformed numerical simulations and elucidated the characteristicsof the impulsive wave pressure acting on the setback parapet duringstorm surge and high waves. Based on this information, we were able
to establish a method of evaluating the stability of sandbags against
overtopping waves. These findings are supplementary to Case Studies of Sandbag Installations in Ports and Harbors to Mitigate Damage Caused by Storm Surges and High Waves (Ports and Harbours
Bureau, Ministry of Land, Infrastructure, Transport and Tourism). We
were also able to elucidate the mechanism of how energy suppression nets could reduce the wave pressure within the joint of caissons.

Activities in FY 2020

• We analyzed the wave observation data acquired through the NOWPHAS (Nationwide Ocean Wave information network for Ports and
HArbourS) in 2019 and published it in the annual report. We also focused on the wave field of Typhoon Faxai, simulating it using a thirdgeneration wave model and analyzing the wave direction (ray tracing)of the swell coming into the bay. The reproducibility of sea surface
winds and Tokyo submarine canyons is crucial for the wave simulation of Tokyo Bay. Our study also indicated that the external swells
that entered Yokohama Port during the typhoon might have caused
significant damage to the adjacent areas.
Experiment of wave force acting on setback parapet

Wave

Collapse from the rear row

Wave
Spatial Distribution of
maximum wave power

Analysis of the ray tracing ofswells entering the bay
Front water depth: 2.5 m
Incident wave height:
0.72 mWave period: 2.8 s

07 PARI Annual Report 2021

Safety factor of overturning (resisting moment/acting moment)

Research Themes and Activities in FY 2020

While Japan has not experienced a storm more devastating than the
Isewan Typhoon that ravaged the nation in September 1959 in terms ofseverity of damage caused by storm surges and high waves, the UnitedStates and the Philippines have also been hit by catastrophic storms
more recently, including Hurricane Katrina in September 2005 and Typhoon Haiyan in November 2013. In future, global warming might bringhigher storm surges and waves than those we have experienced in Japan. Therefore, this research is aimed for changing disaster prevention
and mitigation measures into a pre-disaster stage from post-disasterone and focuses on how to mitigate damage by the maximum storm
surge and wave conditions and how to rapidly recover and reconstruct
after the damage has occurred. Therefore, we conduct research to encourage hard and soft measures.

Maximum inundation height (m)

1C

<
>

No sliding and no overturning
Only sliding

Only overturning

Substantially washed away
Goda wave
pressure
SandbagActing moment

Frictionforce

Sliding<<

Friction coefficient was set
so that the sliding safety
factor becomes 1.0.

Acting force> resisting force
Acting moment< resisting moment

Sliding safety factor (resisting force/acting force)

Experimental results on the stability of sandbags

Research
Research
Themes
Themesand and
Activities
Activities
in FY
in2020FY 2020

2A

Research on Enhancement of Port and Airport Performance forIndustrial CompetitivenessBackground and Objectives

Research and development were conducted on the following topics
to improve the port and airport functions in order to ensure their global
competitiveness.
For the particular objective of improving container terminal productivity, we are developing a container damage inspection system, evaluating numerical simulations of terminals where ICT, etc. are used, andstudying various implementation plans as part of our efforts to promote
digital transformation at ports and harbors, improve their operational
efficiency, facilitate the implementation of environmental measures, andenhance their overall functions.

Planning for Automation of Container Terminals

Activities in FY 2020
(3) Proposal of new technology for container terminal operations
As part of the PRISM (Public/Private R&D Investment Strategic Expansion PrograM) sponsored by the Cabinet Office, we developed an
AI-powered image determination system and conducted its data acquisition test at Daikoku Pier in Yokohama Port during FY2020 with aview to implementing the system in actual port operations in the near
future. This system is capable of making determinations using both image processing and laser measurement data. In addition, we examined
its applicability to PC-18 on Port Island in Kobe Port and prepared its
test manual.
Laserscanners(5 units)

Ceiling LED lights Vertical ceiling cameras Angular ceiling cameras(2 units)(2 units)(15 units)

Approx. 5 m

Approx.
1.5 m

Approx. Approx.
1.7 m 0.5 m

Approx.
2m

on ofDirectimovement
Photoelectric sensors (14 units)

Approx. 0.9 m

Approx. 1.5 m

Approx. 1 m

Approx. 2.5 m

Approx. 5.4 m(1) Proposal of evaluation method to estimate the productivity of
the container terminal system introduced AI and ICT technology orother method
When the parallel container-stacking layout was examined in FY2019,we observed that many trucks had to wait for their turn on the terminal premises where cargo volumes of 1,500,000 TEU were handled per
year. This meant that deploying the number of RTG cranes there in linewith MC-3 and MC-4 would significantly fall short of the required actualcargo throughput. As the terminal had adopted an automated damage
inspection system in FY2020, its overall cargo-handling machinery capacity improved, and the on-premises wait time of the trucks, which
previously had to wait for ten minutes for their turn on average, wasreduced to a short queue of five to six trucks. This improvement is likely
attributable to the fact that this model of a container terminal had undergone a major expansion of space that increased its depth from 500 m
to 700 m, in addition to its vertical layout where an automated transfer
crane (ASC) is always deployed at each lane on the incoming chassis
side, and it was assumed that such a terminal layout would require alarge initial investment. As described above, AutoMod-powered simulations can enable us to examine various future plans by testing different
assumptions. As the current port and harbor plan includes a cargohandling volume of roughly 1,000,000 TEU per year, there should be
sufficient excess capacity according to our simulations.

Bottom photoelectric sensors (2 units)(2) Proposal of planning method for automated container terminalby quantitative numerical simulation
The PIANC finished its WG208 report titled Planning for Automationof Container Terminals and was set to publish it in March 2021. This
190-page book contains information on many of the latest cargo-handling machines, and how they could be deployed in combination withvarious operation systems, etc.

Vertical side cameras Side LED lights(15 units)(2 units)

Angular side cameras(2 units)

Illustration of the container damage inspection system(prototype installed at Yokohama Port)PARI Annual Report 2021 08

Research Themes and Activities in FY 2020

Research Topics

Meanwhile, PARI executed a memorandum of understanding (MOU)
with the National University of Singapore (NUS) jointly with the Overseas Coastal Area Development Institute of Japan and the Japan Association of Cargo-Handling Machinery Systems. Under the MOU, PARI
will form a research alliance not only with the NUS but also other institutions that have executed similar MOUs with the NUS, including theSingapore Maritime Institute and other research centers and universities from Australia, China, Germany, Korea, and the Netherlands, witha view to establishing unified international standards for smart ports.
Through this research alliance, PARI will function as
one of its global partners in
the formation of PortML (portmark-up language) standards
that will facilitate cooperativeinteraction and information
sharing among various port
authorities and users.
When this project is completed, it will facilitate the development of innovative digitaltwin technologies, which will
help enhance the global competitiveness of various parties involved in port and othermaritime operations in Japan.

4

PARI is responsible for research and development to help improve
the functions of ports, harbors, and airports across Japan, as part ofthe country’s efforts to improve the international competitiveness of
its industries and promote port, harbor, and airport development in an
efficient and effective manner, as they are vital to the daily activitiesof the nation’s citizens. PARI’s research in these areas covers the following subthemes and goals that are relevant to Japan’s international
competitiveness, encompassing the country’s global strategic port andharbor policy, improvement of airport functions in the Metropolitan Area
(improvement of Haneda Airport), infrastructure export capability, etc.
These topics are comprehensively studied by various departments of
PARI as part of its overall R&D policy.

Research Themes and Activities in FY 2020

2B

Research on Life Cycle Management of Infrastructures

Background and Objectives

4

The ports, airports and coastal infrastructures that have been in service for a long time are increasing, but financial resources and the number of engineers for facility maintenance are limited. As important port,
airport, and coastal infrastructure functions should be maintained, thestrategic maintenance, renewal, and other measures to maintain suchfunctions are strongly required.
Therefore, we are trying to establish methods for structure design
and material selection which are excellent in terms of maintenance, andwill develop techniques and technologies regarding various countermeasures for maintenance phase.

Research Topics
Research Themes and Activities in FY 2020

Research and development were conducted on infrastructure lifecycle management with emphasis on the following three subthemes:• Concerning technology for inspecting and diagnosing port structures, we examined various inspection and diagnosis techniques andinspection systems.
• We conducted exposure tests on concrete, steel and other materials
to evaluate their long-term durability.
• We examined methods of evaluating the applicability of sustainable
materials to marine environments.

Activities in FY 2020

Research on systems for inspecting and diagnosing infrastructure• Study on the implementation and operation of inspection and diagnosis
techniques for developing the evaluation of marine structure performance
To study the use of underwater drones as an alternative to visual inspections, we tested their effectiveness in a survey of anode wear. During
the test, we deployed underwater drones to measure the electric currents
discharged from anodes while also visually inspecting them, and foundthat underwater drones could be a viable alternative to the conventional
inspection method involving professional divers. However, the test also
indicated that the efficiency of water drone surveys greatly depends on
the skill of the operator. Another study we conducted focused on a monitoring method using an IoT-based inspection and diagnosis system. As
part of this study, we selected a pier to survey the concentration of its
salt accumulation and perform numerical analysis of the wind conditions
underneath it in order to investigate effective positions for installing sensors on the surrounding marine structures. The results revealed that the
spatial distribution of the accumulated salt concentration across the bottom surface of the pier might have been affected by the winds.
• Research and development on techniques to deal with external disturbances affecting inspection equipment operation
As part of our study on the use of ROVs to inspect the superstructuresof piers, we developed a prototype of a stationary positioning system (i.e.,thrust adjustment, countersteering, etc.) utilizing the positioning function
already implemented in the ROVs, which is one of the techniques used todeal with external forces. We also took our ROV designed for inspecting
pier superstructures to the Ajigawa and Taisho areas of Osaka Port toconduct on-site surveys of bottom surface of pier superstructures, andsuccessfully tested the effectiveness of the aforementioned stationary
positioning function as the ROV
hovered in waves in the actual
port environment. In this connection, our published report, Development of a Pier Superstructure
Inspection Robot and a Diagnosis Assistance System, which
included the findings from thisstudy, won the 4th Infrastructure
Maintenance Award for Excellence (jointly sponsored by the Inspection ROV surveying the bottom
MLIT and six other Ministries) in surface of a pier (Taisho, Osaka Port)
January 2021.
09 PARI Annual Report 2021

Research on technologies for prolonging the life of infrastructure• Exposure test on concrete, steel, and other materials to evaluate theirlong-term durability
We set up a long-term exposure test facility to examine a method ofpredicting concrete corrosion induced by chlorine, the cathodic protection characteristics that affect steel bars in reinforced concrete, the concentrated corrosion mechanism of steel components, and the cathodic
protection characteristics present near LWL. We also acquired data on
the durability of various wood materials in this study.
• Development of a performance evaluation method applicable to protective coating methods used on marine structures
We have been continuously performing exposure tests (for 36 years)
at the Hazaki Oceanographical Research Station (HORS) to examinevarious coating methods for protecting steel piles in order to establish
a method for predicting deterioration applicable to protective-coatedsteel structures. In addition, we worked on elucidating the deterioration
mechanism of petrolatum-coated structures based on the findings from
our accelerated weathering and indoor exposure tests along with theaforementioned exposure tests conducted at the HORS. In addition,
we conducted a survey on the superstructure of a pier that had been
surface-coated 18 years ago to evaluate the durability of the protective
coating (surface coating method) applied to concrete structures and totest the effectiveness of our deterioration prediction method.
• Examination of productivity improvement methods applicable to concrete structures at ports
To promote the utilization of precast concrete materials in port structure construction, we created test specimens mimicking joint sectionsof pier-superstructure beams consisting of precast sleeve tubes andsteel-pipe piles in order to perform a peak-to-peak alternating load
experiment and numerical analysis. In this examination, we found thatsuch joint sections possessed a superior energy absorption capacity
compared to the conventional type of pier superstructure joints while
maintaining a similar level of load-bearing capability. In terms of themethod of connection between sleeve tubes and main steel bars, theexperiment indicated that the stress would mainly occur around thefolded sections of those components, and that the stress that wastransmitted to the sleeve tubes and RC beams was not affected by
the diameter-to-thickness ratio of the steel-pipe piles. In addition, we
started performing accelerated deterioration and outdoor exposure experiments on PCa test specimens created by the PC mild-press-joint
method in order to evaluate the durability of component joints.
• Study on the effectiveness of the design and implementation of concrete pavement at airports
Steel nets are typically installed on the concrete pavements at airports to prevent the spread of cracks and maintain the integrity of therebar joints underneath them, while preventing foreign objects fromfalling into the cracks. However, the effectiveness of this design andimplementation method was yet to be proven, so we conducted a study
for this purpose. For this study, we constructed a test pavement andcompared its areas with and without steel-net covering to see if it would
make any difference in terms of crack formation and stress generation,etc., but the comparison showed no significant difference.
Evaluation of the applicability of sustainable materials in marine
environments
On this research topic, our studies encompass evaluation of various
performance indices of concrete components that utilize recycled materials (i.e., applicability, durability, etc.), organization of information on theperformance requirements of port structures made of concrete (mainly
unreinforced) and examination of various evaluation methods for assessing their long-term durability, and evaluation of the applicability of ecofriendly materials (especially recycled materials), etc. (While prior researchmainly focused on durability, we are conducting a more comprehensive
examination including their environmental effects such as CO2 emissions.)

Research
Research
Themes
Themesand and
Activities
Activities
in FY
in2020FY 2020

2C

Research on Effective Use of Existing Infrastructure Facilities

Background and Objectives

Research and development were conducted on the following subthemes for efficient facility renewal, effective use of construction byproduct soil, utilization of waste disposal sites at sea, etc.
Research on techniques to improve or renew existing facilities
To elucidate the fracture process of pier structures and improve ourability to better define the performance requirements of piers, we conducted model experiments to observe how the joint sections of piersuperstructures and steel piles failed, and also used the data acquired
from the previous year’s model experiments to observe their fracture
mechanism based on numerical analysis.
We also worked on developing a method of evaluating the quality of
improved ground through geophysical surveys, and examined how it
could accurately perform detection based on specific resistance differences in indoor experiments, etc.
Research on effective use and techniques of treating construction
byproducts
We started conducting basic research to develop coreless groundsurvey methods. In addition, we started our study on the evaluation of
how defects in solidified and improved soils would affect the overall
strength of improved ground.
Research on management and utilization of waste disposal sites
at seaAlthough we had previously halted our new research on this topic dueto the lack of need to utilize those sites or to resolve related issues, we
decided to keep gathering relevant information to explore such needsin the long term for fundamental research on the future site utilization.

Activities in FY 2020

Research on techniques to improve or renew existing facilities• Elucidation of the fracture process of pier structures to define theperformance requirements of piers in more detail
While the performance requirements of piers can be broken down
into different categories such as usability, repairability, and safety,
the current performance specifications only cover the locations andamounts of residual displacement and plasticized hinges, etc. and failto provide rules on their practical usability and repairability. To address
such shortcomings, it is crucial to understand the fracture process ofentire pier structures in detail, including the behavior of their components following yielding and plasticization. For this purpose, we conducted model experiments to observe the fracture process of the joint
sections between pier superstructures and steel piles, and also use thedata obtained from the previous year’s model experiments on the underground bending behavior of steel piles to reproduce their fracture
behavior based on numerical analysis.

Research on effective use and techniques of treating construction
byproducts• Basic research to develop coreless ground survey methods and establish digital geotechnical engineering
To develop an in-situ digital sampling method that is capable of scanning the core of the original underground soils with an X-ray CT scanner, we operated our internally developed drilling machine, which has
a built-in X-ray CT scanner, on a gravel soil model and measured its
excavation force, etc.
• Evaluation of how defects in solidified and improved soils would affect the overall strength of improved groundWe performed numerical analysis to examine how weak sections
would affect the stress-strain relationship of unconfined compression
test, with the parameters being the strength ratio of weak and sound sections, weak section size, and the locations of the weak sections within thespecimens. The analysis indicated that, if the solidified specimens contained some weak sections, the strain at failure would not increase, while
exhibiting the same effects as crack-type disturbances that would only
result in decreased strength. The analysis implied that such specimens,
which exhibiting the same effects as crack-type disturbances, would
not be suitable for the quality control of ground improvement such as
cement-treatment. The improved ground with weak sections should be
evaluated comprehensively, considering the content rate of the section.
Interface withthe drilling rig

Drilling machine

X-ray
CT scanner

Core tube
Drilling unit

Drilling machine with built-in X-ray CT scanner and drilling experiment
Hole 1

In addition, we examined amethod of creating specimens
containing weak sections. We
were able to confirm that ourgoal of creating specimens
containing unimproved sections could be achieved byplacing a clay slurry that had
been frozen with liquid nitrogen in a mold, pouring a slurryof cement-improved soil into
the mold, and curing it.

Hole 2

Hole 1

Specific
resistance(ohm-m)Hole 2

Specific
resistance(ohm-m)Chemical grout
injection section

Before chemical After chemical
grout injection grout injection

Tomography of specific resistancemeasurement data before and after
the chemical grout injection

PARI Annual Report 2021 10

Research Themes and Activities in FY 2020

Research Topics• Development of a method to evaluate the quality of improved groundthrough geophysical surveys
As no effective method currently exists to three-dimensionally observe the status of improved materials underground after chemical
grout is injected into inhomogeneous ground to prevent liquefaction,
we conducted a study to establish methods of evaluating the quality of
improved ground and construction management based on geophysical surveys that would not require soil sampling. The study involved anindoor model experiment to measure the shape of improved ground in
3-D and also a real-scale measurement experiment to verify the method’s applicability to coastal areas.

4

There is strong demand to improve the functions of existing infrastructure and use them effectively as possible. Requests include measures to handle increasing cargo volume and larger ships and vessels,
diversification of airport functions, and countermeasures to deal withexisting facilities which can no longer be used due to increased external
forces and other reasons. In addition, regarding waste disposal sites
at ports which accept industrial and non-industrial waste, there is social demand for the highly effective use of them. On the other hand, it
has become difficult to secure disposal sites which accept soil dredged
from water channels for shipping routes. Accordingly, it is necessary to
prolong the life of soil disposal sites.
Therefore, we will develop the following: techniques to improve thefunctions of existing infrastructure and to renew and efficiently change
the intended use of existing infrastructure; techniques to reduce or effectively utilize construction byproducts; and techniques to effectively
utilize waste disposal sites at ports.

Research Themes and Activities in FY 2020

3A

Research on Development and Utilization of Oceans

Background and Objectives

4
Research Themes and Activities in FY 2020

Since the 1960s, the importance of marine utilization and development has been pointed out.
Various approaches for this purpose have been taken, but the progress remains inadequate.
One of the reasons is the lack of infrastructure at sea as a hub. Therefore, marine hub ports
should be constructed on remote islands including Minamitorishima Island and OkinotorishimaIsland to promote marine utilization and development. These remote islands are surrounded bysevere sea wave environment and severe sea climate for port construction which are different
from those of general ports in main islands. Further technological development is required toensure smooth ship berthing, cargo-handling, and port construction.
Therefore, in this research theme, we will make maximum use of previously accumulated
knowledge regarding waves, sea-bed soils, port structures, and port construction to construct
ports on remote islands, and will also promote marine utilization and development. Specifically,
we will clarify the characteristics of waves in isolated reef areas, and will develop a new mooring
system for ships. We will also develop technologies for downsizing and reducing the weight ofunderwater acoustic video cameras, as well as utilization and development.

Research Topics

Research and development are being conducted on the following subjects for the development and utilization of oceans.
• For our development of analytical methods applicable to the topographic dynamics of carbonate remote islands, we analyzed the processes and mechanisms of topographical change andground formation and verified the validity of our survey and analysis techniques. Based on ourfindings, we proposed effective methods of surveying and analyzing low-water lines, shorelines, and other topographical features near port facilities, with a view to their preservation.
• For our research on the equipment of underwater construction machines with multiple functions using machine guidance technology, we used profile sonar to conduct an experimenton its external measurement, tested the accuracy of our acoustic positioning system, anddeveloped a remote operation support system.
• For our research on the acoustic imaging system, we explored ways to install acoustic video
cameras on a work vessel, and worked on developing a software program that would enablereal-time monitoring of an ongoing construction project.
• For our research on the horizontal resistance characteristics of pile foundations at offshore
wind power plants, we performed horizontal cyclic loading tests on piles along with related
element tests, worked on enhancing our numerical analysis code for simulating the processof pile penetration, and examined our non-linear spring model of soil that factored in horizontal cyclic loading.
• For our research on the mechanical properties and durability of various infrastructure materials in the deep sea, we designed and produced related testing equipment, and performed
durability experiments in a high-pressure water tank using a low-temperature seawater
circulation system. We also started conducting an exposure experiment on infrastructurematerials in the deep sea, etc.

Activities in FY 2020

• For the development of a fender system for automatic ship berthing/unberthing, we invented
a fender system that has adsorption pads fixed to the front of the fender panel on the fenders
to allow automatic and efficient ship berthing/unberthing and also to enable steady mooring
and cargo-handling operations. In addition, we studied the optimal adsorption pad structurethat could easily cling to the side of a ship, and also examined a prior study on the conceptual structure of a vertical adjuster mechanism that would track a ship’s movement alongwith a change in its draft, which allowed us to create the basic concept of our fender system
for automatic ship berthing/unberthing.
• For our development of analytical methods applicable to the topographic dynamics of carbonate remote islands, we were able to achieve the following. We succeeded in developing a monitoring method that combined
images shot by drones and stationary
cameras and survey data to observe theentire low-water lines and shorelines ofremote islands as well as the topographic
changes occurring around port facilities.
We conducted an on-site experiment on
Iriomote Island in Okinawa Prefecture toprove the method’s effectiveness. We Hybrid drone mounted with a green laser
The manufacturer developed this hybrid drone
also developed a method that could aucapable of charging the onboard battery with atomatically determine the distribution and gasoline-powered generator, thereby extendactivity levels of reef-forming organisms ing the flight time and enhancing the drone’s
using aerial photography, AI, etc.
surveying and aerial photography capabilities.
11 PARI Annual Report 2021

• For our installation of multiple functions in underwater construction machines utilizing machine guidance technology, we enhanced thefoundation-leveler attachment that was developed in the previous year by adding a small
bucket to it for carrying rocks, and tested it on
land to verify its effectiveness. We also conductTopographical data acquired by theed an experiment with it on temporary caisson
green-laser-equipped drone
mounds on Miyako-jima Island in Okinawa Prefecture to perform leveling tasks by remote control immediately after crushed stones had beenpoured in, observed its operational precisionand capability, and identified some key issues tobe addressed before it can be used in the field.
In addition, we explored its application to othertypes of tasks and proposed a system conceptthat could be used for dredging in culverts, etc.
Coral distribution estimated by ourand conducted a tank test to review the perforcoral identification model utilizing
machine learning and aerial drone
mance of wall detection sensors, etc.
photography• For our study on the application of an acoustic imaging system to ICT-based construction
projects, we improved the task-monitoring application program used in the shallow-water
acoustic video cameras including the acoustic image viewing system to increase its effectiveness, especially during leveling, dredging, and replacement tasks. We then trialed it in
the Shinmoji (Phase II) construction project, and successfully demonstrated its usability as aconstruction management system and created an operation manual for it.
• For our study on floating breakwaters equipped with a wave-power generation function,
we performed numerical calculations using a motion simulation program for a floating bodyto examine the optimal shape of such a single-component floating breakwater with wavepower generation devices and its mooring method, and observed how the absorption ofwave energy with generation devices affected the breakwater’s wave-dissipating capability.
We also examined the wave-dissipating capability of a multiple-component floating breakwater with wave-power generation devices by performing simplified numerical calculations
viewing it as an elongated version of the aforementioned single-component floating body.
• For our research on methods of estimating the wave forces affecting offshore wind power
facilities, we are currently conducting a large-scale movable bed experiment to observe
scouring.
• For our study to elucidate the horizontal resistance characteristics of pile foundations foroffshore wind power plants under various fluctuating loads, we conducted a cyclic loading
test using triaxial testing equipment to apply very small loads, and learned that soil stiffness
would be reduced by small repetitive loading. In addition, we conducted a horizontal andcyclic pile-loading experiment in a large soil tank. Furthermore, we developed an analysis
method for elucidating the mechanism of the frictional contact between the soil and therigid bodies installed in it, and applied the method to the phenomenon of pile penetration todemonstrate its validity.
• For our research on load-setting methods for offshore wind turbines in waves and winds, weobserved the dynamic response of offshore wind turbines under several different wind andwave combinations is strongly affected not only by the blade pitch control following windspeeds but also by the wave action. In particular, larger bending moments appear in wave
conditions where the breaking waves occur in shallow water. In addition, we collected meteorological, oceanographic, and structural specification data on offshore wind turbines, andextracted and sorted necessary data for performing load coupled analysis on actual machine
equivalent offshore wind turbines.
• For our evaluation of the mechanical properties and durability of infrastructure materials inthe deep sea, we were able to accomplish the following: We designed and produced a device that would be used to conduct a concrete loading experiment under water pressure.
We started an experiment to observe the deterioration process of cement-based materials
in low-temperature seawater. We placed test specimens on the northern edge of the Nankai
Trough and in another sea area at a depth of 1,680 m and analyzed them after exposure andelucidated their deterioration mechanism. We conducted a laboratory test on hardened cement specimens to observe their water pressure resistance characteristics, and also started
an in-situ monitoring experiment using same-sized specimens on the northern edge of the
Nankai Trough at a depth of 3,500 m.

Research
Research
Themes
Themesand and
Activities
Activities
in FY
in2020FY 2020

4A

Research on Enhancement and Utilization of Coastal Ecology

Background and Objectives

For research and development on the preservation and utilization of coastal
ecosystems, we are focusing on the following subthemes.
• For our research on examining the previously developed global dynamics
model for predicting the speed of carbon dioxide absorption and inundation suppression effects in shallow sea areas, we are continuously gathering
data and knowledge on various factors and processes pertaining to the ecosystems, while integrating and improving its sub-models (i.e., wave model,
topography and sediment model, ecosystem model, etc.).
• For our initiative to create coastal topography and geo-designs that would
both assist disaster mitigation and ecological environment preservation, weare evaluating and analyzing the characteristics of the types of topographicaland soil environment that can maintain resilience during disasters and allow diverse species of organisms to inhabit, while evaluating their disaster mitigatingand energy reduction effects against earthquakes, tsunami, and high waves.
• For our research on techniques to improve the functions of seagrass meadow ecosystems, we are developing a model to explain the maintenance andrestoration mechanism of seagrass meadows, while also examining methodsof facilitating seagrass meadow restoration and assessing their value as afood for fauna inhabiting those meadows in order to evaluate their function
as feeding grounds.
• For our research and development on techniques for mitigating oil pollution, we
are improving our real-time oil movement prediction system, and continuously
examining techniques for mitigating oil pollution, including self-extracting bubble curtains for controlling floating oil, application of such bubble curtains toenvironment management vessels, and extraction of oil from sunk vessels, etc.

Activities in FY 2020

• For the research on examining the global dynamics model for predicting the
speed of carbon dioxide absorption and inundation suppression effects inshallow sea areas, we conducted on-site measurements in large seagrassmeadows to observe their CO2 absorption through dissolved refractory organic carbon discharge. We also conducted in-situ surveys of subtropical bluecarbon ecosystems and quantified the carbon flows among different complex
ecosystems inhabited by mangroves, seagrasses, and corals. The findings
from these studies have enabled us to examine CO2 absorption amounts using the aforementioned global model. In addition, we ran simulations to predict future changes in shallow-water ecosystem areas by the RCP scenario
and published our findings in a scholarly paper. Furthermore, we conducted
in-depth topographical observations of coral reefs to use the data as a basis
for our wave-height reduction calculation using a green-laser-equipped drone.

Quantified carbon flow among different complex ecosystems
consisting of mangroves, seagrasses, and corals (Iriomote Island)• For our project to create coastal topography and geo-designs that would bothassist disaster mitigation and ecological environment preservation, we further
developed our integrated assessment and prediction method applicable tocoastal benthic ecosystems and geo-environmental dynamics for a broad areaof tidal flats and beaches, and used the developed integrated assessment andprediction model to examine how the major changes in coastal topography andgeo-environment caused by meteorological disturbances affected the changes
to benthic ecosystems and the distributions, and proved the model’s efficacy
based on the results of in-situ observations performed in Japan and overseas.
• For the cross-sectional observation and analysis of atmospheric and oceanographic issues at bay mouths, we developed a method to continuously andsteadily conduct atmospheric observations over extended periods including
particulate matter, and performed statistical analysis of wind conditions atbay mouths. In addition, we maintained steady oceanographic observation
operations including pH and other marine conditions.
• For the numerical examination of how aquatic ecosystems are responding
to climate change, we applied the numerical simulation model that we had
previously developed to evaluate the effect that topographical changes have
had on the amounts of seawater exchanged at bay mouths, and found thatthe degree of impact of topographical changes on seawater exchanges fluctuates depending on the location and the time of year.
• For the development of methods to improve the functions of seagrass meadow ecosystems, we evaluated their value as a food for fauna inhabiting thosemeadows in order to evaluate their function as feeding grounds, and developed a simplified model that can explain the maintenance and restoration
mechanism of seagrass meadows.
• For data assimilation study to an actual coastal estuary using real one-year observation data, we conducted the first study to apply the ensemble Kalman filter. It was possible to maintain the ensemble spread by perturbing atmosphericforcing, lateral boundary conditions, and river discharge forcing. This method
achieves robust annual data assimilation and reflects seasonal fluctuations.
• For the research and development on new techniques that can be used toprevent and remove various types of oil spills caused by natural disasters
and other events, we performed an experiment in a large model water tankto test the performance of our next-generation oil recovery system that isbeing developed, and quantitatively showed that its capability is equivalentor superior to that of the current system in terms of oil recovery efficiency. In
addition, we filed a patent application related to this new system. As for thedevelopment of our web-application-type simulator for predicting the movement of oil spills at sea, we were able to develop a scalable calculation engine for accelerating the simulation, and also improved its front-end function
by adding a new function that enables simulation data to be shared among
multiple users. As for our research on the technique to improve the fluidity ofhigh-viscosity oils that remain in sunk vessels so that they can be extracted
more easily, we examined a model that was designed to explain the resultof a previously conducted beaker experiment, and performed tests to verify
the efficacy of the model when it is applied to the hydraulic transmission line
system of a vessel, etc. Based on these research findings, we filed a patentapplication on the concept of our heavy oil recovery method and system.
PARI Annual Report 2021 12

Research Themes and Activities in FY 2020

Research Topics

4

Rich ecosystems in coastal zones include tidal flats, seagrass meadows,
and coral reefs. Coastal zones are valuable places for the global environment.
However, during the era of rapid economic growth, intense socio-economic activities caused the deterioration of water quality especially in coastal inner bays
and enclosed waters, resulting in ecosystem damage. Thanks to subsequent
countermeasures, water quality has gradually been improving in some coastal
zones; however, recovery of the coastal zone environment including ecosystems remains a formidable challenge. Meanwhile, there are new challenges
looming, including the need to utilize the coastal zone functions to alleviate
climate change and to address the issue of large-scale oil spills from coastal
industrial complexes, etc.
Therefore, we are focusing on activities to help restore the coastal environment, alleviate climate change, and develop technologies to better deal withlarge-scale oil spills. We are also working on elucidating the function of coastal
ecosystems in absorbing greenhouse gases (blue carbon) and proposing how
their function could be utilized. In addition, we are developing a new system thatwill be able to predict in real time the status of the aquatic environment in Tokyo
Bay, Ise Bay, etc. including the occurrences of red tides and blue tides. Furthermore, we will be developing a next-generation oil recovery system for use by
the oil recovery fleet owned by the Ministry of Land, Infrastructure, Transport
and Tourism, along with a new technology to deal with oil spills from coastal
industrial complexes, etc. that are caused by earthquakes and tsunami.

Research Themes and Activities in FY 2020

4B

Research on Coastal and Estuarine Processes

Background and Objectives

4
Research Themes and Activities in FY 2020

PARI’s research activity of littoral drift was started to examine the critical water depth of sediment movement for harbor planning. Now, prevention methods against sedimentation and also siltation are proposed.
However, in Japan, sedimentation and siltation are still progressing insome ports, while in other countries their ports are expected to experience far greater amounts of sedimentation and siltation than in Japan,
which indicates that the currently available techniques are inadequate
for addressing this global issue of sedimentation and siltation which
are damaging navigation channels and harbor basins. Meanwhile, many
precious natural beaches were lost during the period of rapid economic
growth, and this negative trend is yet to be reversed. Although the many
benefits that beaches yield for protection, environmental conservation,and human use are clearly recognized, and they are being restored on
certain coastlines by taking measures to suppress coastal erosion,
global warming is also expected to exacerbate coastal erosion in the
future. Also, when remote islands and overseas are taken into account,
it is important to maintain not only beaches but also coral-reef coasts.
PARI is currently focusing on identifying means for effectively preserving both natural coastal topography, such as beaches, mangrove
shorelines, and coral-reef coasts, and artificial coastal features, including navigation channels and harbor basins that are crucial for logistics, despite the ongoing trend of climate change. Furthermore, PARI is
working to predict key changes in coastal erosion as well as sedimentation and siltation affecting navigation channels and harbor basins, andto suggest measures to effectively address these issues while assumingthat the trend of global warming might persist. In addition, we will clarify
siltation processes in the estuaries of large rivers, mangroves and intertidal zone in the Asian countries, and then propose countermeasuresagainst such phenomena.

changes. It was elucidated that the effects of the tidal fluctuations on
the responses of beach morphological changes in the swash zones.
The beach processes were previously unknown and these findings
were also published in an international academic journal and somedomestic news. While the work on generalizing model parameters
is still in progress, we are simultaneously developing a model representing beach profile changes utilizing deep learning. Thus, weare steadily building the methods to perform future beach prediction
from wide-ranging perspectives.

Beach profile changes observed over the past 34 years

Research Topics

For research and development on the formation and preservation ofcoastal topography, we are focusing on the following.
• For the development of a model to predict global coastal morphological changes induced by climate change, we are working on generalizing the parameters of our previously developed model to make themodel applicable to other beaches and to predict the future coastalchanges. We are also developing a deep-learning model for predicting beach profile changes and verifying its applicability.
• For the breakthrough of coastal topographical changes mechanism
and the development of our prediction model, we are continuing with
our on-site observations at the Hazaki Oceanographical Research
Station while working out how to apply our prediction model to thefield of navigation channels, harbor basins, and coastal beaches.
• For the development of a sediment transport control method to minimizee harbor siltation, we are improving our previously developed
sand-mud-mixture bottom sediment model while analyzing related
in-situ data so that the model can be properly applied to actual
coastal zones.

Activities in FY 2020

• We statistically analyzed beach morphological changes previously
obtained on Hasaki beach to evaluate the climate change impacts.
We will use the statistical information as a basis for generalizing
our prediction model with comparing model parameters and beachphysical indices. In particular, we focused on tidal fluctuation (especially those caused by a supermoon), which is one of the water-level

13 PARI Annual Report 2021

Supermoon’s effects on beach morphological changes• As for the clarification of coastal topographic change mechanism andthe development of a coastal topographic change prediction model,
we continuously conducted on-site observation of wind, waves, currents and topographic changes at the Hazaki Oceanographical Research Station. In addition, we improved our prediction model for
topographic changes near pile structures that might occur in the surfzone where the wave and current would change in a complex manner
due to breaking waves.
• For our study to elucidate the mechanism of sediment transport
around estuaries and sedimentation in navigation channels and harbor basins, we improved our previously developed sand-mud-mixture bottom sediment model and analyzed related in-situ data so thatthe model can be applied to actual coastal zones (e.g., in Patimban,
Indonesia). In addition, we analyzed existing in-situ data in a domestic estuarine port, e.g. Niigata Port (West Port district), to develop a
numerical model that can properly simulate the sedimentation mechanism that occurs in the field.

Fundamental
Fundamental
and and
Exploratory
Exploratory
ResearchResearch
Fundamental Research in FY 2020

The fundamental research of waves, beaches, ground, earthquakes,
environments, etc., is the basis of every study conducted by PARI, andtherefore we are actively working on clarifying principles and phenomena, such as the mechanisms of natural phenomena and dynamic behavior of the ground and structures.
Research theme (Fundamental research)

2

Investigation of earthquake disaster3

Development of estimation method for near-fault strong groundmotions4

Development of a new method for predicting liquefaction-induced
ground subsidence and flow

5

Evaluation of the deformation and fracture characteristics
of coastal soil structures in relation to waves and flows, anddevelopment of reinforcement technology

6

Development of the estimation method for local scour aroundcoastal structures due to tsunami

7

Elucidation of oceanographic phenomena based on central
processing and analysis of observation data

8

Identification of issues and improvement of wave estimation
methods applicable to Japan’s coastal areas

9

Evaluation of longterm durability of concrete, steel and various
materials based on exposure test10

Development of the performance evaluation method in protective
coating for marine structures

11

Evaluation of applicability of sustainable materials in the marine
environment

12

Study on application of inspection and diagnosis systems for
improvement of performance evaluation of marine structures

13

Study on process leading to rupture of pier structure for highdefinition of performance regulation

14

Basic research to develop coreless ground survey methods andestablish digital geotechnical engineering

15

Development of analytical methods for the topographic dynamics
of carbonate islands

16

Elucidation of the horizontal resistance characteristics of pilefoundations for offshore wind power plants under various
fluctuating loads

17

Evaluation of the mechanical properties and durability of
infrastructure materials in the deep sea

18

Validation of the newly developed global dynamic model for the
projection of atmospheric CO2 uptake rate and inundation control
in shallow coastal ecosystems

19

Cross-sectional observation and analysis of atmospheric andoceanographic issues at bay mouths

20

Numerical study on responses of aquatic ecosystem to an
environmental change

21

Development of the methods for increasing ecosystem functions
in eelgrass meadow

22

Observation of coastal phenomena at HORS and developmentof numerical simulation of topography change for port andsurrounding beaches

23

Developing future projection model of coastal change in thecontext of climate change

24

Development of sediment transport control method to minimize
harbor siltation

In the cases of the 2018 Hokkaido Eastern Iburi earthquake andthe Sulawesi Indonesia earthquake, the disasters apparently involved
ground subsidence and flow caused by major liquefaction events in theregions’ fine-particle soils that had high silt and clay content. Lead researchers of these disasters have been delivering pioneering results on
a global scale in recent years, in the form of practical liquefaction prediction and flow prediction methods that take into account the irregularcharacteristics of seismic load effects and their durations. Meanwhile, asubsidence and flow prediction method that can be applied to liquefaction of various soils that have highly diverse degrees of granularity andplasticity is yet to be established. Therefore, it is necessary to explore
novel prediction techniques to better understand and deal with the subsidence and flow mechanism of liquefied soils with wide-ranging levelsof granularity and plasticity.
For our FY2020 iteration of this study, the goal of which is to elucidate how subsidence and flow occur in liquefied soils with various
levels of granularity and plasticity, we evaluated and analyzed the liquefaction and subsidence characteristics of soils with widely disparate levels of granularity and plasticity under various types of seismic
loads such as continuous duration, irregularity, and continuous effects
of seismic motions.

Sedimentation of silt and clay content caused by liquefaction-induced sand boiling(Top) Sulawesi earthquake (bottom) 2018 Hokkaido Eastern Iburi
earthquake

PARI Annual Report 2021 14

Fundamental and Exploratory Research

Strong motion earthquake observation in port and airport area

Development of a new method for predicting liquefaction-induced
ground subsidence and flow

5

1

Cases of Fundamental ResearchFundamental
Fundamental
andandExploratory
Exploratory
ResearchResearch
Development of the estimation method for local scour aroundcoastal structures due to tsunami

5
Fundamental and Exploratory Research

Concerning methods of designing breakwaters that are tsunami-resistant, several notable design formulas, including the Tanimoto’ tsunamipressure formula and the hydrostatic pressure formula during tsunami
overflowing were published in the Guidelines on the Tsunami-Resistant
Design of Breakwaters in FY2013. However, there are many instancesof disasters resulting from scouring caused by tsunami overflowing, as
happened at the north breakwater in Hachinohe Port which was devastated by the Great East Japan Earthquake disaster. As little research has
been conducted so far on the phenomenon of scouring caused by tsunami overflowing, it is crucial to facilitate studies to accurately estimate
the amounts of scouring during tsunami attacks. For this purpose, ourstudy entails hydraulic model experiments to observe scouring causedby tsunami overflowing a breakwater (cross-sectional 2D) as well as
scouring that occurs around the head of a breakwater (planar 2D). The
design of this experiment involves varying the diameters of the sandparticles, etc. and observing the armoring effects that are produced bygravel mounds; we are working to develop a scour estimation methodthat has high general applicability. In addition, we are exploring othertechniques for estimating scouring based on particle methods.
For our FY2020 activities, we studied the armoring effects of gravel
mounds and reviewed the performance of scour-prevention mats to minimize scouring caused by tsunami overflowing. We also continued with
our study that was started in FY2019 to examine the tsunami-resistancemeasures that are being implemented on the heads of the breakwaters
at the mouth of Urad Bay for their ability to mitigate local scouring.

rectional wind waves and arrival of swells), especially as to why Yokohama Port suffered most of the damage caused by the typhoon, andconfirmed that the reproduction precision of the wave model would varydepending on the sea wind load products. In addition, we monitored
swell activities entering Tokyo Bay to understand their propagation process, and conducted long-term hindcasting on the Sea of Japan.

Conceptual image of oceanographic phenomena around Yokohama Port
caused by Typhoon Faxai in 2019

Development of the performance evaluation method in protective
coating for marine structures

Movable bed experiment at breakwater head

Scour suppression by installation ofbag-style armor blocks

Identification of issues and improvement of wave estimation methods applicable to Japan’s coastal areas
This study is intended to improve our existing wave model in termsof its ability to simulate or predict the temporal and spatial variation
characteristics of sea breeze, the process of fetch-limited wave development, the sheltering effect of coastlines, and their interaction withseabed topography, which are all specific to coastal areas, and to use
it to perform high-resolution wave simulations for the medium to longterm concerning Japan’s coastal areas.
For our FY2020 activities, we analyzed the wave fields that occurredin Tokyo Bay during Typhoon Faxai in 2019, formulated a plausible hypothesis for a mechanical process that explained the wave conditions
that arose in the open sea near Yokohama Port (i.e., formation of bidi15 PARI Annual Report 2021

Generally, two types of corrosion-prevention treatment are applied tosteel marine structures simultaneously, namely cathodic protection andprotective coating, to ensure their long-term durability. Regarding protective coating techniques, their deterioration characteristics (usable
lifespan, etc.) are being elucidated through exposure tests, etc. However,while it is essential to review the anticipated performance of each protective coating technique in the design phase, there is no established method to evaluate its current corrosion-prevention capability or predict its future state for the maintenance and management phase. To address this,we have been continuously conducting exposure tests at the pier of our
Hazaki Oceanographical Research Station and other locations to track
the temporal changes in the condition of the corrosion-preventing techniques applied to their steel piles to evaluate the durability of the protective coating materials in the marine environment. In addition, we reviewed
the results of surveys conducted on various port structures, etc. that had
been jointly used for extended periods (over 20 years), analyzed someof the samples taken, and evaluated the durability-enhancing ability ofeach of the corrosion-prevention techniques that were applied. Furthermore, we organized the results of exposure tests conducted on petrolatum coating techniques to elucidate the related deterioration mechanismand establish a methodof evaluating the performance of petrolatumbased coating materials.
In addition, we studied
the results of previous
surveys conducted on
actual structures (i.e.,pier superstructures at
Yokohama Port) andused the data to evaluate the performance ofthe concrete surface
coating materials thatwere applied to thosestructures.
Exposure test on petrolatum coating method

Fundamental
Fundamental
and and
Exploratory
Exploratory
ResearchResearch

As it is difficult to define detailed performance requirements for any
given port facility in a necessary and sufficient manner in relation to theactual performance requirements for use, the current practice of facility
design in the field is not yet sufficient to allow the structural components of each pier being built to perform to their maximum potential.
To accurately assess the actual usability and repairability of a pier, it isnecessary to observe it after its components have failed so that the rupturing process that affected the entire pier structure can be understoodin detail, including its behavior following plasticization. To address allthese points, we are closely observing the rupturing process of entirepier structures in detail, accurately evaluating the resistance behavior of
the pier piles and joint sections following plasticization, and exploring
methods of controlling the rupturing process affecting the entire pierstructures.
For our FY2020 activities, we numerically analyzed the result of themodel experiments conducted in the previous year and attempted toelucidate the rupturing behavior. In addition, we conducted new modelexperiments to observe the process through which the joint sections ofpier superstructures and steel piles would become damaged.

In a number of ports in Japan and overseas, countermeasuresagainst sedimentation of navigation channels and harbor basins due
to sediment discharge from rivers and sediment movement by forcing
factors (e.g., tides and waves) are required. As dredging of such navigation channels to keep their necessary depths involve issues of maintenance dredging costs as well as the need to secure sites for disposingof dredged sediments, it is necessary to develop methods for reducing
the volume of dredged sediments and maintaining management of such
port operations in an efficient manner. While it is important to properly
predict the amounts of sedimentation in the channels and basins forplanning the future efficient maintenance strategy and designing appropriate sediment control countermeasures, the complex mechanismof sediment transport processes in-situ still provide us with various issues that must be resolved for the application of numerical simulations.
Our present study involves using in-situ bathymetric data to improve
the accuracy of our numerical model for prediction of siltation of navigation channels and harbor basins, and the development of a numericalprediction system suitable for simulation of siltation in arbitrary shapesof ports and harbors anywhere in South East Asia and other countries.
As for our FY2020 activities, we analyzed in-situ data and improved
our previously developed sand-mud-mixture sediment model so thatit can be applied to coastal areas (e.g., Patimban, Indonesia). We also
discussed the sediment dynamics including the fluid mud transport in
Niigata Port (West Port district) through analysis of the in-situ data on
the sedimentary processes.

Slide base(range of motion: ±150 mm)

Hydraulic jack(press motion: 3000 kN, 200 mm)

440

Load cell(capacity pressure: 3000 kN)

Load cell (capacity: ±2000 kN)

600
Test
specimen

2060

Hydraulic jack(±2000 kN, 300 mm)

400

Simulation reproducing wave fields off the Patimban coast
1500

Conceptual illustration of our model experiment for observing the
behavior of pile heads following plasticization

Numerical study on responses of aquatic ecosystem to an environmental change
Understanding how aquatic ecosystems respond to changes in theirenvironment is useful for clarifying their current phenomena as well as
for formulating future environmental measures. To achieve this objective, it is essential to gather in-situ observation data, but the knowledge
that can be obtained from numerical simulations is also useful for aquantitative approach.
Accordingly, we conducted a study using our previously developed
numerical model by applying it to a bay adjacent to a city to quantitatively simulate the environmental changes that had occurred there andhow the ecosystem had responded to those changes. For our FY2020
activities, we managed to examine models that reflected cutting-edge
science including the non-hydrostatic model, detritus cycles, fish models, etc., and prepared necessary models and arranged basic data to be
input to the models, etc.

Topographical data representation of the sea zone by Patimban Port
after its construction

PARI Annual Report 2021 16

Fundamental and Exploratory Research

Development of sediment transport control method to minimize
harbor siltation

5

Study on process leading to rupture of pier structure for high definition of performance regulation

Fundamental
Fundamental
andandExploratory
Exploratory
ResearchResearch

Exploratory Research in FY 2020
In FY 2020, exploratory research projects based on ingenious and/or advanced ideas that could potentially lead to new research fields for
PARI in the future were carried out.

Examination of the seawater-induced deterioration mechanism inconcrete materials that are cured under high-temperature conditions in an early stage
Delayed ettringite formation (DEF), which causes cement paste toexpand undesirably, is a deterioration phenomenon that is not yet well
Examination of methods for measuring marine structures with underwater drones

understood. If the rate of use of incinerator ash for cement and precast

In this study, we conducted examinations and experiments on thetific understanding of the DEF-induced expansion behavior of cement,

use of underwater drones mainly to measure the remaining amounts

5of electrolytic protection on marine structures and the improvementof underwater drone operability in murky waters, etc. with a view toenhancing the drones’ usability in actual on-site operations. For theseobjectives, we mainly gathered information on techniques for measur-

Fundamental and Exploratory Researching the remaining amounts of electrolytic protection that could be usedwith underwater drones, and reviewed specific measurement methods

that drones can perform. We also researched information on simplified
sonar devices that could be mounted on underwater drones and exam-

ined how effective they would be in improving the drones’ operability.
Furthermore, we took our underwater drone mounted with a simplified
sonar to our laboratory water tank and sea areas outside to observe

its operability and verify its on-site measurement capability, and thus

were able to determine the effectiveness of using underwater drones formeasuring marine structures, and also identified key issues that need
to be resolved.

In this demonstration test, we successfully used the underwater

drone to visually inspect

cement increases, DEF-induced deterioration of marine structures is
expected to increase also in Japan. However, there is very little scien-etc. in the marine environment where DEF is facilitated. Therefore, ourultimate goal is to monitor and comprehend such behavior in an environment with high exposure to seawater, so that DEF can be con-trolled from the material design phase. The objective of this study is toobserve the DEF-induced expansion behavior facilitated by seawaterand understand the mechanism. To this end, we prepared mortar test
specimens and cement paste powder and submerged them in tap water (or distilled water) and seawater, which revealed that the expansion

rate of the mortar specimens immersed in the seawater tended to belower than those placed in the tap water. However, this tendency was

not universal among all specimens tested, which might be explained by
the effects of different W/C mixture rates and other ions contained in theseawater besides Na+ and Cl-. We also measured the expansion rate of

the cement paste powder specimens and found that those placed in theseawater tended to expand less than those in the tap water. Therefore,
the potential expansion induced by DEF may be lower if the object isimmersed in seawater than in fresh water.

anodes and measure an-ode currents, and verified

our theory that underwater

Sonardrones could be used in-stead of the conventional
method using human div-

ers. Furthermore, we wereable to verify the possibility
that ROVs and other robots

could be used to survey
marine structures entirely
unmanned in the future.

Positionmonitoring
cameraClip

Underwater drone used in the study
Intact concrete

However, submarine sur-veys near the seabed which
are murky or where the de-vice’s thruster could cause
sediment turbulence might
be unable to visually inspect

anodes easily. Hence, we

considered that the efficiency of any given survey

largely depends on the skillsof the underwater drone op-

erator; this issue requires
further study.

17 PARI Annual Report 2021

Image of underwater drone
measuring anode current

Concrete affected by DEF-induced expansion

Fundamental
Fundamental
and and
Exploratory
Exploratory
ResearchResearch

In this study, we chose to apply AI (deep learning), which is enabling

Consideration of uncertainty in external force characteristics forresponse evaluation of offshore wind turbine

major progress in various scientific fields, to improve the quality of opti-

In the design of offshore wind turbines, at first, we typically estimate

image model to create data sets, we observed them and determinedeach time series data of wind speed and water surface elevation by
applying random number seeds to energy spectra, and then we per-form time history response analysis by using them. In addition, we needto perform analysis on tens of thousands of cases or more to various
external loads. However, only a few time series response analysis isperformed for each pair of wind and wave loads due to the large numberof cases of analysis, and statistical stability of data is not ensured. Asof the external loads at the time history level, the response values could

be underestimated or overestimated depending on how random seeds
are applied. In this study, we attempted to develop a new method thatbines while considering the uncertain properties of the loads involved.
As a result, it is found that the application of combination of a point

estimation method and a probability density function approximation

method, defined as a simplified response evaluation method here, tocharacteristic value of wave loads enables us to evaluate the dynamic

response taking into account the uncertainty of external loads without
an immense amount of time history response analyses. It also was implied that our method could be used not only to reduce the load conditions for design but also to evaluate the response based on the probabilistic approach which is not used in current design.

were more widely distributed with this approach compared to theexisting method. We were subsequently able to create artificial data

representing more widely diverse deterioration characteristics using
the approach. In addition, we succeeded in performing high-precisioncalculations by reformulation through Monte Carlo integration. We thenapplied the artificial data to develop and optimize an AI program andachieved superior results both quantitatively and qualitatively comparedto the conventional method, whereby submarine images of significant-ly deteriorated quality could be restored, with their overall blue tone
mostly removed. We also conducted a tank experiment that involved

adding various amounts of milk to create shades of murkiness and tak-ing color-chart images so that image restoration could be evaluated.
Such tests proved that our developed AI was also effective for restoring
actual image data and could be applied to a variety of tasks involving

submarine image acquisition. These findings suggest that our AI-based

technique could be used to survey the surrounding environment in any

underwater task, inspect port facilities, monitor coral reefs, measuresubmarine robot positions, explore natural resources under the sea, etc.

Overall, this method is expected to improve the efficiency of many tasks

that must be performed underwater while helping reduce the workloadof divers, etc. performing such tasks.

Randomnumber ①
Wind speed
ﬂuctuation
Water surface
elevation
Bending
momentRandomnumber ②
Wind speed
ﬂuctuation
Water surface
elevation# Tens of thousands of design conditions# One pair of statistical loads→ several pieces of time history data
# Overestimation/underestimation of
response

Bending
momentRelation between time history load and response dataAI-based improvement of underwater operation images
Low water transparency and high murkiness hinder the optical rec-ognition of external objects. If optical submarine images are of poor
quality due to such factors, the conventional approach to improving

them is to use expensive optical devices, a dedicated system and hard-ware, but these are costly and not optimal for general application. In
addition, while acoustic measurement using sonar, etc. is common withsuch optical image acquisition and processing, it typically yields large

estimation errors, and must be executed by an experienced and skilled
operator, among other issues.

Images before (top) and after (bottom)
application of the proposed method

PARI Annual Report 2021 18

Fundamental and Exploratory Research

could simply evaluate the response characteristics of offshore wind tur-that the quantitative indices of deterioration such as PSNR and SSIM

5such method does not properly factor in the uncertain characteristics

cal images acquired in water. After using a highly intricate submarinePublished Research Papers
Number of Peer-reviewed papers in FY 2020
Number of papers in Japanese

Number of papers in non-Japanese languages

Total

Rate of papers in non-Japanese language

66

71

137

51.8%

* The above numbers contain proceedings that only reviewed the abstract.

Papers Published in PARI Reports in FY 2020

6
Published Research Papers

No.

Title

LanguageMonth/Year

59-1-1

Field observation and statistical analyses of the
fugacity of carbon dioxide in shallow coastal waters

Kazufumi TADA, Tatsuki TOKORO, Kenta WATANABE,
Hirotada MOKI, Tomohiro KUWAE

Author(s)Japanese

June 2020

59-1-2Fundamental study on harbor waves sheltered byimpermeable submerged breakwater

Katsuya HIRAYAMA, Yuuki HAMANO, Junya NAGANUMAJapanese

June 2020

59-2-1

Investigation of applicability of coral based aggregate
on marine concrete structures

Takahiro NISHIDA, Toru YAMAJI, Kazuhide YONAMINE,
Osamu TANIGUCHI (Penta-Ocean Construction), Ryoichi TANAKA(Toa Corporation), Hiroshi TAKENAKA (Toyo Construction),
Osamu KIYOMIYA (Waseda University)

Japanese

September
2020

59-2-2Centrifuge model tests for investigation of instability ofseawall ground due to ocean waves

Hidenori TAKAHASHIJapanese

September
2020

59-2-3

Interface shear properties between steel-slag-mixed
dredged soils and different materials

Satoshi MATSUMURA, Takaaki MIZUTANI, Yoshiyuki MORIKAWA,
Yuzo AKASHI (Nippon Steel), Hideki HONDA (JFE Steel),
Masahiro SHIMIZU (Nippon Steel Nisshin Co.)

Japanese

September
2020

59-2-4

Advanced method for identification of windsea andswell on the multi-modal directional wave spectrum

Takashi FUJIKI, Koji KAWAGUCHIJapanese

September
2020

59-3-1

Processes of internal erosion, cavity formation andcollapse under various soil and hydraulic conditions
with their countermeasures using geotechnical filter

Kenta KUDAI, Shinji SASSA, Soonbo YANG,
Kouhei TAKADA, Kojiro SUZUKI

Japanese

December2020

59-3-2Development and application of integrated platform
for predicting and evaluating coastal benthic ecologygeoenvironmental dynamics

Soonbo YANG, Shinji SASSA, Kenta KUDAI, Kouhei TAKADA

Japanese

December2020

LanguageMonth/Year

Haruo YONEYAMA

Japanese

June 2020

Papers Published in PARI Technical Notes in FY 2020
No.

Title

Evaluation of mooring methods for a ship in remote
No.1372
island ports based on allowable wave heights

Author(s)No.1373

Environmental DNA metabarcoding and diversity
analysis for the fish community in coastal areas

Shinya HOSOKAWA, Kyosuke MOMOTA,
Shota OKURA, Takashi KOMURO

Japanese

June 2020

No.1374

Load tests of piles that support jacket structures at
Tokyo International Cruise Terminal

Takaaki MIZUTANIJapanese

September
2020

No.1375

Suggestion of design method for upgrading sheet pile
quay wall

Shunta NAKAMURA, Takaaki MIZUTANI,
Satoshi MATSUMURA, Shintaro KAGIMOTO

Japanese

September
2020

No.1376

Sand-mud mixture transport model for prediction ofmorphological change in estuaries

Taichi KOSAKO, Yasuyuki NAKAGAWA

Japanese

September
2020

Analytical study on the effect of strengthening
No.1378 of caisson components by solidification of fillingmaterials in caisson

Yuichiro KAWABATA, Yutaka TANAKA, Ema KATO,
Yosuke OHYA, Yoshiyuki MORIKAWA

Japanese

December
2020

Meteorological, storm surge and wave characteristics
No.1379 of Typhoon Faxai, 2019 and major inundation in
Yokohama Port

Hiroyasu KAWAI, Kojiro SUZUKI, Katsuya HIRAYAMA,
Koji KAWAGUCHI, Kota YAMAMOTO, Kazuhiko HONDA,
Daiki SATOMURA, Naoki TSURUTA, Takashi FUJIKI, Yu CHIDA,
Takumu IWAMOTO, Shota ASAHI,
Shingo KAWAGUCHI, Hiroki KUBOTAJapanese

December
2020

Shuji NOGAMI, Ema KATO

Japanese

December
2020

Japanese

March 2021

Japanese

March 2021

Satoshi NAKAMURA

Japanese

March 2021

Takahiro SUGANO, Tomotsuka TAKAYAMA, Tetsuya HIRAISHI,
Ryoukei AZUMA, Nozomi YONEYAMA, Hitoshi GOTO,
Hiroyuki IKARI, Akira TATSUMI, Yosuke NAGASAKA, Yu CHIDA,
Katsuhide NISHIZONO, Takamitsu FUKAZAWA, Koji TONOMO,
Akito SONE, Toshiyuki HIRAI, Kozo KAMIDE, Tadao ITO,
Hideaki HANDA, Haruhiko MATSUOKA, Takeshi KONISHI,
Ryosuke TANAKA, Mitsunobu YOSHIDA, Takanobu YAMAMOTO

Japanese

March 2021

No.1380

A feasibility study of an underwater drone for safe andeffective investigation of port structures

No.1381

Annual Report on Nationwide Ocean Wave Information Koji KAWAGUCHI, Kanichirou YOSHIDA,
Network for Ports and Harbours (NOWPHAS 2019)
Takashi FUJIKI, Hitoshi TAMURA

In situ accuracy verification and calibration of windNo.1382 speed and direction meter on a ship: Study using a ferry Shinya HOSOKAWA, Shota OKURA
on a regular service route at the mouth of Tokyo Bay
No.1383

Surrounding scouring of surf zone structure andchanging uniformity of coast in longshore direction

Evaluation of performance and applicability of hydroNo.1384 plane type tsunami breakwater
Appendix: Technical and design manual (draft)

19 PARI Annual Report 2021

The Open Institute
Annual Report, Technical Journals,
and HP

Open to the Public
The FY 2020 event has been cancelled due to prevent
spreading of the COVID-19, and difficulty of ensuring a safe
environment for participants. Due to lose opportunity to learn
about the institute by the cancellation of opening to the public access to the facility, we have established a new Virtual
Public Access page on our HP.

Other Outreach Activities
Cooperation with Super Science High school (SSH) Projects
For students of Yokosuka High School in Kanagawa Prefecture, which is designated as an SSH school by the Ministry of Education, Culture, Sports, Science and Technology,
we provided guidance on the preparation of research projects and conducted tours of the institute's facilities, in orderto encourage students' interest in the institute.

7
The Open Institute“The Annual Report2020” (Japanese version)and “The PARI Annual
Report 2020” (English
version), which concisely
summarized our activities in FY 2019, were prepared as a record of ourachievements and distributed to the related institutions and posted on
PARI HP.
Regarding “The PARI
Technical Journal”, weselected special articles
The PARI Technical Journalof each research theme
for every issue to introduce utilization situations of research
results and PARI’s experiment and on-site observation facilities. Approximately 2,200 copies of “The PARI Technical
Journal” are distributing to approximately 1,600 places.
On HP, we provided various information on events andnews including our institute summarized information, results,
facilities, symposiums on a real time basis; we got approximately 120,000 accesses in FY 2020.

Open to the Public

Implementation of lectures for the
General Public
Port and Airport Technology Lecture
In cooperation with the National Institute for Land and Infrastructure Management (NILIM), a lecture on port and airport technology was held remotely on January 20, 2021, with
an audience of 157 lines, for the purpose of publicizing anddisseminating the results of surveys, research and technological development conducted by the institute.

Students listening to a researcher’s lectureBook publication
To commemorate the 10th anniversary of the Great East
Japan Earthquake on March 11, 2021, a book titled, “Kizuna(Bonds); to protect Lives from Tsunami” was published by
the International Promotion Committee for Tsunami/Coastal
Disaster Resilience Technology, for which PARI serves as
secretariat.

Special lecture by Dr. Yabuki from Osaka University

Port and Airport Technology Special Lecture in Region
In cooperation with the National Institute for Land and Infrastructure Management (NILIM) and Regional Development
Bureaus and other institutes, the seminars were held in small
number of venues or remotely in five regions across Japan,
with a total of about 400 participants, for the purpose of theseminars was to provide a wide range of information on the
research activities and results of the institute and to gather
information on research needs in each region.

“Kizuna (Bonds); to protect Livesfrom Tsunami”

PARI Annual Report 2021 20

Outstanding Research Activities
Awards for Papers and Others in FY 2020
Award

Institution

Date

1

Daiki TAKANO Senior Researcher, Soil Mechanics
and Geo-Environment Group GeotechnicalEngineering Department

Soils and Foundations 2019
Editorial Board Member Award

Japanese Geotechnical Society

July 29, 2020

2

Toru YAMAJI Director, Structural Engineering
Department (Head, Materials Group)

ConMat'20 Best Paper Award

Scientific Committee of
ConMat'20

August 10, 2020

Evaluation of durability ofconcrete used for wave
dissipating block based onfield survey

3

Shinji SASSA Head, Soil Dynamics Group
Geotechnical Engineering Department

Infrastructure Technology
Development Award

Japan Institute of Countryology and Engineering
Coastal Development Instituteof Technology

September 16,
2020

Method of reducing wave
forces that pass throughcaisson joints to prevent
collapse and suction (netbuffer construction method)

Distinguished Paper Award(Telford Premium)Institution of Civil Engineers,
U.K.

October 5, 2020

Centrifuge modelling of
breaking waves and seashore
groundOctober 5, 2020

Extension of unsaturated
soil mechanics and its
applications

8

Name

Remarks

Hidenori TAKAHASH Head, Soil Stabilization Group
Geotechnical Engineering Department

Outstanding Research Activities

4

Yoshiyuki MORIKAWA Director, GeotechnicalEngineering Department
Hiroaki KASHIMA Senior Researcher, Coastal andOcean Development Group, Coastal and Ocean
Development Department

5

Yuri SUGIYAMA Researcher, Soil Mechanics andGeo-Environment Group Geotechnical Engineering
Department

Distinguished Paper Award(Telford Premium)Institution of Civil Engineers,
U.K.

6

Kazuhide YONAMINE Researcher, Materials Group
Structural Engineering Department

Annual Academic Lecture
SessionExcellent Paper Award

Japan Society of Civil
Engineers

Koji KAWAGUCHI Head, Marine Information Group,
Ocean Hydrodynamics Department
7

Takashi FUJIKI Senior Researcher, Marine
Information Group Ocean Hydrodynamics
Department

8

Kenta KUDAI Researcher, Soil Dynamics Group
Geotechnical Engineering Department

9

Akihiko KONDO Senior Researcher, Earthquake andStructural Dynamics Group, Earthquake Disaster
Prevention Engineering Department

21 PARI Annual Report 2021

October 15,
2020

Changes in workability due totransportation and pumpingof concrete with high-level
replacement of copper slag
fine aggregate

Coastal Engineering Paper
Award

Japan Society of Civil
Engineers
Coastal Engineering Committee

October 28,
2020

Improvement of stability
and reliability of directional
spectra observed with
Doppler-type directional
wave meter (Lead author:
Dr. Noriaki HASHIMOTO,
Professor, Kyushu University)

Coastal Engineering Paper
Encouragement Award

Japan Society of Civil
Engineers

October 28,
2020

Prediction of collapse ofunderground cavity fromground surface displacement
and its countermeasuresagainst internal erosion

Excellence Award

Ministry of Land,
Infrastructure Technology
Research Society

November 12,
2020

Development of engineering
methods for anti-seismic
reinforcement and restorationof pile-supported piers withthe use of damper materials

PARI Events
Active participation in International Conferences,
Workshops, and etc.

Conclusion of Education and Research Cooperation
Agreements

Following the establishment of November 5, Japan's Tsunami Disaster Prevention Day, as “World Tsunami Awareness Day” at the United
Nations General Assembly in December 2015, the Goryo HAMAGUCHIInternational Prize (Minister of Land, Infrastructure, Transport and Tourism Prize) was established in 2016 for those who have made outstanding achievements in the field of coastal disaster prevention technology,
including tsunami disaster prevention, and the award was presented on
November 4, 2020 to two persons and one organization: Dr. Fumihiko
IMAMURA, Director of the International Research Institute of Disaster
Science, Tohoku University, and Professor of Tsunami Engineering;
Professor Costas Synolakis, University of Southern California (Greeceand USA); and the Aceh Tsunami Museum (Aceh Province, Republic ofIndonesia).

Based on the "Cooperative Graduate School System," in which
the institute and national, public, and private universities conclude anagreement and researchers from the institute become professors at
graduate schools and supervise graduate students in research books,
etc., the institute has concluded cooperative agreements with 12 universities including Tokyo Institute of Technology, Nagoya University, andNagaoka University of Technology.
In FY2020, we dispatched 14 lecturers. In addition to the cooperative
graduate school system, a total of six lecturers were dispatched to the
Nagoya Institute of Technology, etc.

Promotion of Administrative Support
The Fukushima earthquake that occurred on February 13, 2021
caused damage to the port of Soma, and the institute dispatched four
members to the site as a joint investigation team with the National Institute for Land and Infrastructure Management (NILIM).

9

A prize awarding ceremony and commemorative lecture of the
Goryo Hamaguchi Award (November 4, 2020, Tokyo)

Wide Range of Exchanges with Domestic andOverseas Research Institutes
In order to further improve the quality and efficiency of our research,
we have been actively promoting collaboration with domestic and overseas research institutions, and as of FY2020, we have concluded a totalof 40 research cooperation agreements: 13 in Japan and 27 overseas.
In FY2020, we concluded a cooperative agreement with Singapore University for the digital twin of container terminals newly.

PARI Events

At the PIANC (World Association for Waterborne Transport
Infrastructure),PARI played an important role in promoting strategic international activities, such as setting up MarCom WG225 (Seismic Design of Port Structures) as its chairman and aiming for the 2022 revisionof the "Guidelines for Seismic Design of Port Structures," and participating as a key member in MarCom WG208 (Automation of Container
Terminals) and compiling the "Planning Methodology for AutomatedContainer Terminals (published in March 2021).”
In addition, PARI gave a keynote speech at the International Workshop of the International Society of Geotechnical Engineering (ISSMGE)
as the chairperson of the technical committee, and participated in theInternational Symposium on Automation and Robotics in Construction(ISARC2020) as the secretariat, and engaged in active technical exchanges with overseas research institutions.

Damage investigation at Soma Port

Dispatching of members to Various Technical Committees, etc.
A total of 125 researchers were dispatched to serve as members ofvarious technical committees held by the national and local governments to solve technical problems related to the implementation of
public works such as ports, coasts, and airports.
In addition, if we include the technical committees established byvarious institutions for port, coastal and airport development and airport
maintenance, we have dispatched a total of 410 members, who have
responded energetically to solve technical problems faced by the government and other organizations.
Support for Operations related to Technical Standards for Portsand Harbors
With regard to technical standards for port facilities, we have cooperated by participating as a member of committees established by thePort and Harbor Bureaus of the Ministry of Land, Infrastructure, Transport and Tourism. We also cooperated in the dissemination of technical standards at workshops held by the National Institute for Land andInfrastructure Management, academic societies, and related organizations. As for airport facilities, we cooperated with various study committees for the smooth dissemination and operation of technical standards
for airport civil engineering facilities.
Support for the Evaluation of New Technologies
At the request of the Ministry of Land, Infrastructure, Transport andTourism (including regional development bureaus, etc.), we dispatchedresearchers to the "Evaluation Council for New Technologies" established by each organization to evaluate the applicability of technologies
registered in the "New Technology Application System for Public Works,etc. (commonly known as NETIS)" to the field in order to promote theuse of useful new technologies, and provided technical support.

PARI Annual Report 2021 22

October 2021

−Creating Technologies that Contribute to the World−

National Institute of Maritime, Port and Aviation Technology

Port and Airport Research Institute3-1-1 Nagase, Yokosuka, Kanagawa 239-0826, JAPAN TEL +81-46-844-5040 FAX +81-46-844-5072 URL https://www.pari.go.jp

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