基于环境激励的平原水库动力特性及动弹模反演研究

南水北调东线工程双王城水库为一典型的平原水库,基于环境激励下现场振动测试的实测数据,运用协方差驱动的随机子空间法并结合稳定图研究了双王城水库的动力特性,采用遗传算法进行了水库堤坝动弹性模量的反演分析。模态识别结果表明,双王城水库典型断面处基频范围为1.86~2.98 Hz,阻尼比范围为1.43%~3.67%,频率识别的阶次与环境激励的大小呈正相关趋势。反演结果表明,遗传算法联合ABAQUS软件可以高效地进行结构的参数反演,基于多方向实测频率联合反演的精度要高于单方向。对比依据多方向实测频率反演结果计算得到的频率值与实测值可以发现,各断面第一阶频率的误差均在4%以内,证明了反演分析结果的正确性。因此,模态识别成果和参数反演结果可以为类似平原水库的动力分析提供参考。

Ambient excitation based inversion study on dynamic characteristics and dynamic elastic modulus of embankment for plain reservoir

Shuangwangcheng Reservoir for the East Route of the South to North Water Transfer Project is a typical plain reservoir. The dynamic characteristics of the embankment of the reservoir is studied herein with the covariance driven stochastic subspace method combined with the relevant stabilization diagram in accordance with the measured data obtained from the in situ vibration testing under the ambient excitation， and then the inversion analysis on the dynamic elastic modulus of the reservoir embankment is carried out with genetic algorithm. The result of the modal identification shows that the range of the fundamental frequency at the typical section of the embankment of Shuangwangcheng Reservoir is 1.86～2.98 Hz with the damping ratio range of 1.43%～3.67%， while the order of frequency identification presents a trend of positive correlation with the intensity of ambient excitation. The inversion result indicates that the inversion of structural parameter can be efficiently carried out with genetic algorithm combined with the software of ABAQUS， for which the precision of the measured multidirectional frequency based joint inversion is higher than that from the unidirectional one. Through comparing the frequency value obtained from the inversion of the value of the measured multidirectional frequency with the measured value， it can be found out that the errors of the first order frequencies of all the sections are within 4%， by which the correctness of the inversion analysis result is verified. Therefore， both the modal identification result and the parameter inversion result can provide a reference for the dynamic analysis on the similar embankment of plain reservoir.