1.Research on Earthquake Disaster Prevention

Background and Objectives

A large-scale earthquake disaster is predicted due to the Tokai, Tonankai, or Nankai earthquakes. Technological developments for earthquake disaster prevention are required for port and airport facilities. Unsolved tasks include understanding the characteristics of long-period and long-duration　seismic ground motion from huge subduction-zone earthquakes such as the Tokai earthquake. Ground motion characteristics are not fully understood due to varied local ground soil characteristics in the targeted areas. Verification methods of anti-seismic structure performance require improved accuracy. Improvement is also required in relation to seismic performance of newly built structures, and cost reduction in seismic measures must be improved. Enormous efforts have been made to stimulate technological capacity to address these issues.

Research topics

This research theme has four focal topics: (1) seismic ground motion observations and post-event damage surveys, (2) predicting seismic ground motion, (3) prediction of soil　behavior during earthquakes, and (4) predictions of structural　damage during earthquakes and its　countermeasures.
Post-event damage surveys, continued observation of seismic strong ground motion to elucidate severe seismic ground motion, and monitoring to comprehend ground and structure behavior during seismic strong ground motions must be performed to obtain fundamental knowledge for earthquake disaster prevention.
Appropriate set-up of seismic ground motions for the design of port and airport facilities requires the proposals and practical utilizations of seismic source models, evaluation of nonlinear behavior of surface strata, and more accurate evaluation methods of strong ground motion.
Long-period and long-duration seismic ground motion are predicted during large-scale earthquakes, therefore reliability of predictions and countermeasures must be improved for combined behavior of soil and structure due to these ground motions.

Activities in FY 2010

This research has four focal topics: (1) seismic ground motion observations and post-event damage surveys, (2) predicting seismic ground motion, (3) prediction of soil behavior during earthquakes, and (4) predictions of structural damage during earthquakes and countermeasures.
Post-event damage surveys, continued observation of strong seismic ground motion to elucidate severe seismic ground motion, and monitoring to comprehend ground and structure behavior during strong seismic ground motion must be performed to obtain fundamental knowledge for earthquake disaster prevention.
Appropriate set-up of seismic ground motions for the design of port and airport facilities requires proposals for and practical utilizations of seismic source models, evaluation of nonlinear behavior of surface strata, and more accurate evaluation methods of strong ground motion.
Long-period and long-duration seismic ground motion are predicted during large-scale earthquakes. The reliability of predictions and countermeasures must be improved for the combined behavior of soil and structure due to these ground motions.

Constructions of a countermeasure against liquefaction at Niigata Airport

We have proposed a verification method of liquefaction regarding the characteristics of seismic waves based on experiments and analysis on liquefaction characteristics during long-period and long-duration earthquake ground motions.
Further, we have examined the application of grid-shaped solidification behind quay-walls as a countermeasure against large-scale earthquakes to identify its performance and proposed an applicable range.
We proposed a countermeasure of a double tiered method which improves the seismic performance of existing sheet pile quay walls without stopping cargo handling operations. Its effectiveness was confirmed with a verification of seismic performance and implemented at Sendai-Shiogama port.

Reinforcement of a double tieback method to utilize quay-walls

In addition to clarifying dynamic characteristics in the existing seismic isolation system container cranes, we have developed a device to equip the berth for containers against long-period and long-duration earthquake ground motions and also provided technical support aiming to produce an
actual container crane equipped with the function.
In 2010, we conducted a damage investigation of the Chilean earthquake and tsunami to understand its destruction process from multiple damage of seismic motions and tsunamis. Thus, we developed and established the first facility of the Large-scale Geotechnical and Hydraulic Centrifuge apparatus in the world to cooperate with researchers on earthquake, tsunami, geotechnique and structure as well as initiate development in experiment technologies as a research tool.