During the 1995 Hyogoken-Nanbu Earthquake, the earthquake motion of maximum acceleration of 82.3gal(cm/s2) was observed at the Ikehara Arch Dam, which is located in the Kii Peninsular in the western part of Japan. The Ikehara Dam is a non-symmetric dome-shape arch dam, whose height and crest length are 111m and 460m, respectively. In regard to the dynamic analysis, the values of dynamic deformation properties of dam and foundation will have significant effects upon the dynamic stresses and strains calculated by the analysis. For this reason, in order to improve the accuracy and reliability of evaluation about the earthquake safety of dams, the dynamic deformation property values of dam and foundation should be qualitatively evaluated based on the real phenomena. Therefore, we made 3-D reproduction analysis in regard to the real earthquake behavior of the Ikehara Dam during the 1995 Hyogoken-Nanbu Earthquake by using the 3-D coupled dam-foundation-reservoir system model. And we evaluated the dynamic deformation property values of dam and foundation quantitatively. As the results, the dynamic shear modulus and the damping factor of the dam were evaluated to be 13,500N/mm2 and 2%, respectively. Similarly, the dynamic shear modulus and the damping factor of the foundation were evaluated to be 11,700N/mm2 and 3%, respectively. In this case, as the level of earthquake motions is not so large, the real behavior can be well reproduced by the linear analysis, not by the nonlinear dynamic analysis. In case of very strong earthquake motions, it is considered that the nonlinear dynamic analysis taking not only the non-linearity of dam material but also the discontinuous behavior of joints should be taken into account.
展开▼
