Kenji YAMADA

Dynamic Response Analysis of Earth Structures Based on Finite Deformation Theory

Satoru OHTSUKA

In Niigataken Chuetsu Earthquake Disaster in 2004, many fill structures for roads and building sites were heavily damaged and failed. After Hansin Earthquake Disaster in 1995, the design standard of earth structures for the level2 earthquake motion has been established. However, the estimation for residual deformation of earth structures is still difficult and is left for the future study. In this study, the author developed a dynamic response analysis code based on finite deformation theory to consider the inertia force applied for deformed body by earthquake. The applicability of developed program was strictly examined. The equivalent linear elastic analysis was introduced into to take into account the change in stiffness and damping ratio dependent of strain level. It was widely observed that the damages of earth structures developed by a series of aftershocks. On the basis of this fact, the author numerically simulated the development of deformation for sequent earthquake vibrations.
The following conclusions were obtained in this study.
(1) Developed program for dynamic response analysis was examined through one-dimensional case studies in comparison with theoretical solutions. The validity was confirmed by several conditions of (1) static conditions, (2) propagation speed of wave and (3) free vibration for damped condition.
(2) Comparison between finite deformation theory and infinitesimal deformation theory showed little difference in case studies on slope. Further examination is necessary to discuss the advance of developed program to conventional analysis.
(3) Equivalent linear elastic analysis showed a proper estimation on dynamic response in comparison with elastic-plastic computation results.
(4) Development of deformation for sequent earthquake vibration was numerically simulated with developed program. Equivalent linear elastic concept was introduced into to take account of soil property. The applicability was qualitatively presented, but the future subjects were left. The treatment of boundary condition in vibration problem is expected arranged.