Q值测量的等效声阻抗法  

Equivalent Acoustic Impedance Technique for Measuring Q Value

作　　者：李伟东[1] 叶林[1] 施行觉[1] 

机构地区：[1]中国科学技术大学地球和空间科学系,合肥230026

出　　处：《地震研究》2000年第3期324-328,共5页Journal of Seismological Research

基　　金：国家自然科学基金!(498740 43);地震科学联合基金!(1980 90 )资助项目

摘　　要：回顾了实验室中超声波测量Q值的四种常用方法 :上升时间法、回声法、频谱振比法和波形反演法。在综合了回声法和频谱振幅比法优点的基础上 ,提出等效声阻抗法。该方法借助于参考样品 ,利用其一、二次波的振幅谱 ,计算换能器和耦合层的等效声阻抗 ,进而由待测样品的一、二次波振幅谱计算其衰减 ,求得其与频率有关的Q值。对振幅谱进行了扩散校正 ,并利用该方法测量了有机玻璃和饱水岩石样品的Q值。对该方法的可靠性也进行了讨论。The four common ultrasonic methods for measuring Q value in the laboratory, rise time, pulse echo, spectral ration and waveform inversion techniques are reviewed. Based on synthesizing advantages of the pulse echo and spectral ration techniques, a new method, the equivalent acoustic impedance technique is proposed. Using spectra of the first and second waves in reference, the equivalent acoustic impedance of the transducer and couplet is calculated; attenuation of the sample is estimated by analyzing the spectra of the first and second waves in it, and the Q value spectrum for the sample is obtained from the attenuation finally. Diffraction for the spectra is corrected and the Q values of organic glass and water-saturated rock samples are measured. The reliability of this method is also discussed.

关 键 词：Q值 超声波 等效声阻抗 岩石 

分 类 号：P584[天文地球—岩石学]