Model for the seismic analysis of arch dams including interaction effects
Abstract
A three-dimensional boundary element model for the seismic analysis of arch dams is presented. The soil and the dam are assumed to be viscoelastic domains the former being boundless. The water is assume to be compressible subject to small amplitude motions. The three domains are discretized into B ."E. in a single model which includes a rigurous representation of the dam-foundation rock interaction, the water-foundation rock interaction and the traveling wave effects. The response of an arch dam (The Morrow Point dam) to harmonic waves propagating vertically is studied. The important influence of the abovementioned interaction and traveling wave effects is clearly shown by computed results. These results are in contrast with sorne obtained by other authors using a F.E. model.
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Model for the seismic analysis of arch dams including interaction effects J. Dominguez Unil'ersidad de Sevilla. Spain O.Maesa Unii'ersidad de Las Palmas de Gran Canarias. Spain ABSTRACT: A three-dimensional boundary element model for the seismic analysis of arch dams is presented. The soil and the dam are assumed to be viscoelastic domains the former being boundless. The water is assume to be compressible subject to small amplitude motions. The three domains are discretized into B ."E. in a single model which includes a rigurous representation of the dam-foundation rock interaction, the water-foundation rock interaction and the traveling wave effects. The response of an arch dam (The Morrow Point dam) to harmonic waves propagating vertically is studied. The important influence of the abovementioned interaction and traveling wave effects is clearly shown by computed results. These results are in contrast with sorne obtained by other authors using a F.E. model. 1 INTRODUCTION The analysis of the seismic response of dam-reservoir systems is an important problem within the field of earthquake engineering. The seismic response can not be st udied considering the structure as an isolated body under the influence of a uniform base motion. There are important effects due to the space distribution of the excitation, the dam-water, dam-foundation and water-foundation interaction, that make necessary the use of models including the three media and the interaction between them. A great · effort has been dedicated to this subject in the last t�o decades. The studies of Hall and Chopra (1983) and Fok and Chopra (1986) who analysed the significance of a number .of factors contributing to the responsee shold be mentioned. Those studies have been done using the Finite Element Method. The model of Fok and Chopra (1986} led to an extraordinary advance in the earthquake analysis of arch dams. However it still contains important simplifications which may give rise to unrealistic results. It 's main simplifying assumptions and limitations are: 4601 a) The model includes a massless foundations which is only justified by the necessity of representing a boundless compliant foundation using a finit-e inodel. The soil-structure interaction is not properly represented and the traveling wave effects can not be taken into account. Very recently Zhang and Chopra (1991) have started to analyse an alt.ernative to this model of · the foundation using a two-dimensional boundary �ntegral formulation combined with a Fourier expansion. bl A bottom absortion coefficient is u sed to represent the water-foundation interaction. It is based on the one dimensional .representation of the wave réflection between the water and a uniform half-space. e) The model does not take into account the jo int water-foundation-dam interaction.The model of ·the foúndation rock used for the interaction with the dam is independent of that used for the water-foundation rock interaction. d) The assumption of an uniform cross · sect-ion extending from the vicinity of the dam to i�finity may