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This research aims to evaluate the effect of cyclic loading due to
earthquake on foundation and crushable volcanic soil ground, which widely
distributed over Japan. The various laboratory tests such as cyclic
triaxial test, torsional shear test and non-destructive in-situ test, e.g.
elastic wave exploration are performed for studying the strength-deformation
characteristics and developing the estimation method of liquefaction strength of
crushable volcanic soil ground. Based on the characteristics of breakable
granular materials, analytical research on dynamic deformation behaviors during
earthquake and volcanic activity are also investigated.
Strain-controlled type cyclic triaxial test apparatus (to
see dynamic deformation behavior)
Stress-controlled
type cyclic triaxial test apparatus (to obtain liquefaction
strength)
One of the test
materials (Tomikawa Volcanic Soil)
Example of torsional shear test results : Initial state
before shearing (Left), Deformation after shearing
(right)
The objective of this research is to elucidate cyclic
plastic deformation of granular materials such as crush stones and gravel.
Based on the results obtained by element tests, model tests and numerical
analyses, we examine cyclic plastic deformation of railroad ballast and roadbed
structures subjected to seismic loads or traffic loads, and estimate the dynamic
response of ballasted track to earthquake motions and the progressive failure of
roadbed structures under cyclic moving loads. These research achievements
help us to establish the evaluation method of life cycle costs for maintenance
of civil structures, the risk analysis on geotechnical hazard, the rational
earthquake-resistance design considering the ductility of geotechnical structures.
Shear deformation behavior
of granular material obtained by Ring Shear test
Test apparatus (Left), Deformation
after shearing (right)
Dynamic behavior of railroad ballast
in shaking table tests
Initial State before shaking (left),
Deformation after shaking
(right) 
Simulations of shaking table tests with discontinuous
analysis
Initial State before
shaking (left), Deformation after shaking
(right)
In maritime field, settlement
of coastal structure is significantly induced due to large lateral deformation
of ground beneath a structure subjected to various dynamic loadings such as wave
force. It is necessary for design of ground-structure system that the
mechanism of lateral flow deformation behavior under cyclic loading conditions
can be evaluated by simple technique. In this study, to clarify the
mechanism of deformation of ground-structure system, a series of analysis,
together with the model tests were performed. Especially, the relationship
between the lateral flow deformation of sand ground and the settlement of a
structure is investigated.
Lateral flow deformation of sand ground due to cyclic
vertical loadings
