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Sassa S.,Port and Airport Research Institute | Yamazaki H.,Port and Airport Research Institute
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2017

This paper presents a new simplified liquefaction prediction and assessment method that is capable of considering the influence of the waveforms and durations of earthquakes. The concept of an effective number of waves was introduced to represent the characteristics of the irregularity of waveforms and the different number of load cycles of irregular seismic motions, as well as their influence on the occurrence of liquefaction. A comprehensive set of laboratory liquefaction tests and statistical analyses were performed to study and validate this concept. The validity of the proposed method, which adopts a wave correction coefficient based on the proposed concept, was verified using the case histories of five past major earthquakes, demonstrating that the predictive capability of the new method was improved compared with that of the conventional method for the cases of liquefaction and no liquefaction. A unique feature of the new simplified method is its universality, allowing it to be applied to various types of liquefaction charts, facilitating more-rational liquefaction prediction and assessment worldwide.


Grant
Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENV.2013.6.4-3 | Award Amount: 7.88M | Year: 2013

The NEAM (North East Atlantic, Mediterranean and Adjacent Seas) region of IOC/UNESCO is known to be exposed to tsunamis and, like other regions of the world, faces increasing levels of risk due to i) continuous development of coastal areas with critical infrastructure, and ii) year-round presence of millions of tourists. In recent years, European researchers have greatly advanced knowledge of tsunami hazards and implementation of operational infrastructure, such as creation of a regional system of candidate tsunami-watch providers (CTWP) and national tsunami warning centers (NTWC). However, significant gaps remain and more effort is needed. ASTARTE (Assessment STrategy And Risk for Tsunami in Europe) aims to develop a comprehensive strategy to mitigate tsunami impact in this region. To achieve this goal, an interdisciplinary consortium has been assembled. It includes all CTWPs of NEAM and expert institutions across Europe and worldwide. ASTARTE will improve i) basic knowledge of tsunami generation and recurrence going beyond simple catalogues, with novel empirical data and new statistical analyses for assessing long-term recurrence and hazards of large events in sensitive areas of NEAM, ii) numerical techniques for tsunami simulation, with focus on real-time codes and novel statistical emulation approaches, and iii) methods for assessment of hazard, vulnerability, and risk. ASTARTE will also provide i) guidelines for tsunami Eurocodes,ii) better tools for forecast and warning for CTWPs and NTWCs, and iii) guidelines for decision makers to increase sustainability and resilience of coastal communities. In summary, ASTARTE will develop basic scientific and technical elements allowing for a significant enhancement of the Tsunami Warning System in the NEAM region in terms of monitoring, early warning and forecast, governance and resilience. Overall, this will lead to the goal of the European/NEAM Horizon 2020 strategy: to foster tsunami resilient communities.


Watabe Y.,Port and Airport Research Institute | Noguchi T.,Kanto Regional Development Bureau
Soils and Foundations | Year: 2011

Tokyo International Airport (Haneda Airport) is a domestic hub-airport in Japan; however, the increasing number of passengers has brought it close to its capacity. In addition, there has been strong demand for the development of an international-flight network. Consequently, a new runway, called the "D-runway," was planned and constructed from March 2007 to October 2010. Because some of the D-runway runs through a river mouth, a hybrid structure consisting of piled pier and reclamation fill was adopted. To overcome the geotechnical difficulties in constructing this hybrid structure on the soft clay deposit, various technologies in design and construction were adopted. This paper provides an outline of the project, the ground investigation, and the design of the D-runway structure from a geotechnical engineering view point. From the results of the site investigation, the stratigraphic model at the site was clarified. For the clay layers, a representative depth-profile for each soil parameter was determined. Some local soil properties which tended to be overlooked when only employing an engineering point of view can be appropriately captured by linking the geological and geotechnical information. In the construction of the D-runway, not only the ground improvement technologies (SD, SCP, and CDM) but also the new developed construction materials (the pneumatic mixing of cement treated soil and air-foam treated lightweight soil) were utilized. In the-D-runway project, various technologies used in previous airport constructions were brought together and applied to the ground investigation, design, construction work, and even maintenance. The construction of the D-runway was completed safely, rapidly, and economically, and it came into use on 21 October 2010, on schedule.


Kuriyama Y.,Port and Airport Research Institute
Coastal Engineering | Year: 2012

A wave-averaged process-based one-dimensional model for beach profile change was developed to predict the cyclic evolution of longshore bars. The cross-shore sediment transport was assumed to be composed of suspended load due to wave breaking and bed load due to velocity skewness, acceleration skewness, and beach slope. The model's performance was investigated using the beach profile data obtained every weekday during a 12-year period from 1989 to 2000 along a 400-m long pier at the Hazaki Oceanographical Research Station, located on the Hasaki coast of Japan, where the mean duration of bar evolution is approximately 1. year. The model was unable to reproduce bar development from a rather flat profile, possibly because some sediment movement process was missing in the model. However, the model calibrated with a 1-year data set, including the bar evolution cycle consisting of bar generation, seaward migration, decay, and new bar generation, can be used to predict the first cycles of bar evolution at Hasaki. © 2011 Elsevier B.V.


Kitazume M.,Port and Airport Research Institute
Proceedings of the Institution of Civil Engineers: Ground Improvement | Year: 2011

The quality of deep-mixed soil (improved soil by in situ mixing) depends upon a number of factors including the type and condition of native soil, the type and amount of binder, and the production process. The quality assurance/ quality control (QA/QC) practice which focuses upon the quality of deep-mixed soil was originally established in Japan and Nordic countries and has been accepted worldwide for more than three decades. It comprises a laboratory mix test, field trial installation, monitoring and control of construction parameters during production and the verification by measuring the engineering characteristics of deep-mixed soil either by unconfined compression tests on core samples or by sounding. Diversification of application, soil type and execution system, together with the improved understanding on the behaviour of deep-mixed ground in the past two decades make it necessary for our profession to review the current QA/QC practice. Based on the literature review and the International collaborative study, the authors discussed the similarity and differences in the QA/QC procedures employed in different parts of the world and proposed the future research needs in a keynote lecture at Okinawa 2009 Deep Mixing Symposium. The current paper is a summary of this keynote address.


Hirayama K.,Port and Airport Research Institute
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2013

A nonlinear wave transformation model which can calculate the distribution of wave height inside a harbor with good accuracy has been used to estimate harbor tranquility. In a conventional procedure, however, the characteristics of such calculation could not be applied enough because the variation of wave height ratio with the steepness of incident waves would be ignored in prediction of an occurrence probability of wave height inside a harbor from one of offshore waves. In this paper, an appropriate procedure of harbor tranquility analysis for using a Boussinesq-type wave transformation model is proposed and its applicability is demonstrated in a harbor on coral reef topography. Copyright © 2013 by the International Society of Offshore and Polar Engineers (ISOPE).


Kuriyama Y.,Port and Airport Research Institute | Banno M.,Port and Airport Research Institute | Suzuki T.,Yokohama National University
Geophysical Research Letters | Year: 2012

The interannual shoreline variation during a 22-year period from 1987 to 2008 at the Hasaki coast located in eastern Japan was found to be induced by the fluctuation of the deep water wave energy flux using an empirical shoreline prediction model. The correlation coefficients between the deep water wave energy flux and climate indices showed that the wave energy flux has a positive correlation with the Arctic Oscillation (AO) index during the period from January to April, and negative correlations with the Nino-West Sea Surface Temperature (SST) anomaly and the Southern Oscillation Index (SOI) during the period from September to December. The shoreline prediction model using the correlations between the wave energy flux and climate indices indicated that the large-scale variations in climate represented by the AO index, the SOI, and the Nino-West SST anomaly accounted for 45% of the interannual shoreline variation. Copyright 2012 by the American Geophysical Union.


Kuriyama Y.,Port and Airport Research Institute
Coastal Engineering Journal | Year: 2010

A one-dimensional parametric model for undertow and longshore current velocities as-suming a triangular velocity distribution in a surface roller was developed. This model as well as a parametric model with the assumption of a uniform velocity distribution in a roller was compared with eld data obtained on barred beaches at Hasaki in Japan and at Duck in the USA. The comparisons showed that the present model predicted the velocity elds at the two sites reasonably well, and the prediction accuracy of the present model is slightly better than that of the other model. However, the present model underpredicted the undertow velocities on the trough regions, and overestimated the longshore current velocities near the shorelines. © World Scientific Publishing Company and Japan Society of Civil Engineers.


Matsuzaki Y.,Port and Airport Research Institute
Marine Pollution Bulletin | Year: 2016

Despite many previous in situ estimates of horizontal diffusivity below the sea surface, horizontal diffusivity at the sea surface, which is a parameter required in the prediction of oil diffusion, has not been formulated. This study conducted in situ estimations to quantify horizontal diffusivity at the sea surface. To measure the horizontal diffusivity at and below the sea surface, clusters of thin sponge rubbers (simulating spilled oil), together with drifting buoys, were deployed on successive occasions in Sagami Bay, Japan. The experimental results revealed that horizontal diffusivity was larger at the sea surface than below. Based on the results, a procedure for estimating horizontal diffusivity at the sea surface was introduced to predict the diffusion of spilled oil, which was verified using numerical simulations. The simulation results showed good agreement with observations, suggesting the procedure is appropriate for the estimation of horizontal diffusivity at the sea surface. © 2016.


Sassa S.,Port and Airport Research Institute
Geotechnical Engineering | Year: 2014

The paper reports some recent research advances on tsunami-seabed-structure interaction following the 2011 off the Pacific Coast of Tohoku Earthquake Tsunami, Japan. It presents a concise review of the latest research performed on the stability of breakwater foundation under tsunami by utilizing a geotechnical centrifuge and a large-scale hydro flume at Port and Airport Research Institute. I highlight here the role of tsunami-induced seepage in piping/boiling, erosion and bearing capacity decrease and failure of the rubble/seabed foundation. A comparison and discussion are made on the stability assessment for the design of tsunami-resistant structures on the basis of the results from both geo-centrifuge and large-scale hydrodynamic experiments.

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