基于小波包变换的二滩大坝地震响应能量分析

Energy Analysis of Ertan Dam Seismic Response Based on Wavelet Packet Transform

由于地震响应信号具有明显的非平稳特性,为分析其在不同频带的能量分布规律,结合实际地震监测数据,利用小波包分析良好的时频局部化性质和均匀频带划分能力,对二滩大坝地震动响应信号进行研究。首先,简略地对比了小波变换与小波包变换的异同,讨论了基小波选取的侧重点,提出了小波基混频度的概念,并作为选取小波基的评判指标;其次,对坝体不同位置响应信号在不同频段内进行展开,讨论了不同测点、不同方向上响应信号能量在各频带上的分布规律;最后,总结了结构响应信号的能量在频带上的分布与信号的方向及结构的位置关系。研究结果可为大坝的抗震减振以及与能量相关的安全评估方法提供理论基础。

In order to analyze the energy distribution of the seismic response signal in different frequency bands that have distinct non-stationary characteristics,according to the actual seismic monitoring data,the wavelet packet analysis,which has good characteristics of time-frequency localization and a uniform band division capacity,is used to analyze the Ertan dam seismic response signals.First,the similarities and differences between the wavelet transform,wavelet packet transform and the choice of mother wavelet are briefly introduced,and the concept of wavelet frequency-aliasing index is proposed and selected as an index of choosing the mother wavelet.Second,the differences in energy distribution of response signals from different locations and directions which is expanded in different frequency bands are discussed.Finally,the relationship between location,direction and energy distribution is obtained.The results provide a theoretical basis for the seismic analysis of dams,as well as for energy-related safety assessment methods.