基于小波分析的地震动转动分量研究

基于强震时断层附近地面地震动转动分量对单摆式地震仪水平和竖向摆造成的响应差异性,建立采用小波分析获取地震动转动分量的方法。首先采用离散小波变换探讨未修正地震动水平和竖向分量的局部时频特性;进而在水平和竖向分量低频差异性的基础上,建立新的阈值处理方法对水平分量的小波系数进行处理,从而获取了地震动转动分量;最后,通过振动台试验验证了基于小波分析的地震动转动分量获取方法的正确性和精度。结果表明:基于小波分析获取的地震动转动分量的残余倾斜位移与实测的基本吻合,且过滤掉转动分量的水平分量傅里叶谱的低频部分与竖向分量的较为相似;振动台试验验证了基于小波分析获取地震动摇摆分量方法的正确性,且相较于基于傅里叶分析的方法,结果与实际情况更加吻合,精度实现了大幅提高。

Rotational components of ground motion based on wavelet analysis

The rotational components of strong ground motion near faults have differences in the response to the horizontal and vertical pendulums of seismograph, and according to this principle, a method for obtaining the rotational components of ground motion is established using the wavelet anlysis. The local time-frequency characteristics of uncorrected horizontal and vertical earthquake accelerograms using the discrete wavelet transform are discussed. Then a new threshold method, which processes the wavelet coefficients for horizontal earthquake accelerograms, is established to obtain the rotational components of ground motion. Finally, the correctness and precision of the method for obtaining the rotational components using the wavelet analysis is verified through shaking table tests. The results show that the calculated residual tilt displacement of rotational components of ground motion is consistent with the actual one. And the low-frequency part of the horizontal Fourier spectra of ground motion with the rotational component being filtered out is similar to the vertical ones. The correctness of the proposed method is verified through shaking table tests. Compared with the results processed by the Fourier analysis, the wavelet analysis can achieve more accurate results, and it is consistent with the actual situation.