Modal Parameter Identification and Inverse Analysis of Longyangxia Gravity Arch Dam
In this paper,the modal parameters of Longyangxia gravity arch dam are identified by stochastic sub-space identification method.The three-dimensional dam-foundation-reservoir finite element model of Long-yangxia gravity arch dam is established,and the water pressure is simulated by using the Westergaard added mass formula.The parameters of the homogeneous foundation model and the layered foundation model of differ-ent water levels are inverted and their dynamic characteristics are analyzed.The results show that the first order frequency of Longyangxia gravity arch dam is between 2.778 Hz and 3.196 Hz.The elastic modulus of the dam body obtained by inversion using the additional mass method is about 50 GPa to 52 GPa.For the average founda-tion,the elastic modulus is 30 GPa;for the layered foundation,the elastic modulus in the area below the 2 490 m elevation is 34 GPa.The elastic modulus of the dam body and the foundation modulus obtained by the inverse analysis are significantly larger compared to their design values.The first vibration mode is positive sym-metry,the second vibration mode is antisymmetric,and the third vibration mode is positive symmetry.The second-order frequency of the Longyangxia gravity arch dam is much bigger than the first-order frequency,which are similar to the natural vibration frequency distribution characteristics of the gravity dam.
Longyangxia arch dammodal parameters identificationfinite element methoddynamic charac-teristicsfluid-structure couplingmodal analysis
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