1A.Research on Seismic Disaster Prevention and Mitigation

Background and Objectives

  • Massive earthquakes of around magnitude 9 (such as the one that may occur in the Nankai Trough) are expected to cause large-scale damage, thus research and development for enhanced disaster protection and prompt recovery from disasters are essential for ports and airport facilities, which are fundamental social infrastructure for the distribution of goods an-d movement of people.
  • Therefore, this theme involves research and development for improving earthquake resistance while reducing construction costs, which are based on the diagnosis and performance
    verification of the earthquake resistance of facilities and correspond to the characteristics of long-period, long-duration seismic ground motion expected to occur in the case of a huge subduction earthquake and the seismic ground motion characteristics varying depending on local
    ground soil characteristics. The research and development are being conducted mainly on methods for investigating and diagnosing earthquake resistance as well as construction methods that improve the resistance, while using existing facilities with limited design life erected during the era of rapid economic growth.

Research topics

 Concerning this research theme, research and development are conducted based on an understanding of phenomena covering everything from seismic sources to the facilities concerned. 

  1. Study on Seismic Performance of Facilities based on Strong Motion Observation, Field Damage Monitoring System
     Continued observation of strong earthquakes for clarifying seismic ground motion, publication of data via the website, automatic email distribution system, PARI technical notes, etc., post-event damage surveys, and monitoring for clarifying the movement of the ground and structures during earthquakes are being conducted. In addition, GPS abnormality monitoring devices are being developed and used in actual damage surveys.
  2. Research on Tsunami Disaster Prevention and Mitigation
     The use of SPGA models, which can reproduce the records of the 2011 Great East Japan Earthquake and are proposed as a method for predicting seismic ground motions of (M9-class) earthquakes centered on the Nankai Trough, which is becoming increasingly likely to occur, is being promoted, while a method for evaluating the nonlinear behavior of the ground and a rational method for setting up seismic ground motions over a wider area are being reflected in practical work.
  3. Research on Prediction of Seismic Performance of Soil-Structure System and Countermeasures
     A long-period, long-duration seismic ground motion is expected to occur in the case of a (M9-class) earthquake centered on the Nankai Trough. Research is being conducted on the prediction and countermeasures against the dynamic behavior of ground-structure systems in the case of such a seismic ground motion. Particularly, in order to make it possible to investigate, diagnose, and improve earthquake resistance while using existing facilities with limited design life, research and development are being conducted by combining the observation of strong earthquakes, earthquake damage surveys, model experiments, and numerical analyses.

Activities in FY 2014

  • 2,354 records obtained from 135 strong motion seismographs throughout Japan in 2013 were corrected according to the instruments used and published via the website, immediate email distribution system, and PARI technical notes.
  • A damage survey report on the 2011 Great East Japan Earthquake was summarized in cooperation with relevant organizations.
  • A new method of predicting strong earthquakes with good reproducibility of massive seismic waveforms (SPGA model) was verified using actual data and increasingly applied to the design of facilities in various places.
  • A dynamic model of steel pipe piles having a large diameter-to-thickness ratio which are used at ports, as well as a reinforcing method using new materials, were proposed for evaluating the earthquake resistance of pile-type foundation structures and methods of reinforcing them.This proposal has reached the application stage in "Study on simple methods for evaluating the earthquake resistance of existing mooring facilities (New research in FY 2014)" and is expected to be utilized in "Study on the validity of the temporary use of piles in the case of a disaster based on abnormality measurement" utilizing GPS and "Study on reinforcement for restarting use."
  • As an economical construction method to mitigate liquefaction damage to existing facilities, the applicability of the "Liquefaction countermeasure construction method by shear deformation control" to runways, taxiways, and aprons was examined through experiments and analyses, and then a design verification method was proposed.

 

Figure 1.1.1.1 Strong-motion earthquake observation network in port areas

 

 

Figure 1.1.1.2 Reinforcement using new materials (by approx. 30%)

 

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