Analyses Of Seismic Response And Permanent Deformation For Rockfill Dams Under Strong Earthquakes

China is rich in water resources, but also is an earthquake-prone country. Since a number of rockfill dams lie in high seismic-intensity regions, it is necessary to investigate their seismic response behaviors and aseismic safeties under strong earthquakes. Hence, it has the important practical significance to make a study on this subject. In this study, the analyses of seismic response and permanent deformation for rockfill dams are carried out and some results are obtained by use of the finite element method. The main content of the study is as follows:(1) According to a lot of research literature, some constitutive models of rockfill materials for static and dynamic analyses of rockfill dams are discussed and the basic theory of the finite element method and the numerical calculation flow are summarized.(2) Based on the platform of the finite element software ABAQUS, the UMAT subroutine of the3D multi-mechanism model is implemented and investigated for its accuracy and stability.(3) The seismic response analyses of the asphalt-concrete-faced rockfill dam are carried out by use of the3D multi-mechanism model and the equivalent viscoelastic model during a strong earthquake. The dynamic response characteristic of the dam and the effect of constitutive models on its response are investigated. The result shows that there exist some differences in the dynamic responses of the dam computed by use of two constitutive models. The3D multi-mechanism model can accurately simulate the complex stress-strain relationships of rockfill materials under earthquake loading and the result computed by it can reasonably reveal the nonlinear seismic response characteristic of the dam. (4) Based on Tatsuoka’s cumulative damage theory of soil strains under irregular loadings, a numerical analysis method of the earthquake-induced permanent deformation of rockfill dams is proposed. By use of the mechanical experiment results of the rockfill materials, the material parameters related to the stress-strain relationship and cumulative strain model are determined. By use of the proposed method, the earthquake-induced permanent deformation characteristics of the rockfill dam under construction and after completion are studied respectively during the strong earthquake. The result shows that the earthquake-induced settlement computed by the proposed method is basically consistent with the measured one under the construction of the dam. Moreover, the predicted value of the earthquake-induced settlement at the crest after the completion of the dam is within the reasonable range by comparison of the measured data of the other similar dams.