【作者】 贺智娟；

【导师】 雷宛；

【作者基本信息】 成都理工大学 ， 地球探测与信息技术， 2010， 硕士

【摘要】 声波探测技术是以弹性波传播理论为基础,主要研究声波在岩石中的传播规律及由结构面所形成的波阻抗界面对声波传播的影响,为工程地质评价,特别是岩体稳定性评价提供重要依据。目前岩体声波探测技术主要利用其运动学特征——纵波速度这一参数,至于动力学特征则利用得较少。为了进一步对声波多种参数进行综合分析,本文选取某水电站工区实测声波信号,利用Matlab软件及所编写程序对其进行小波时频分析研究,取得以下成果：(1)对实测声波检测信号进行小波分解和重构,提取去除噪声的低频重构信号进行分析,通过一系列信噪评价标准确定了最佳分解层数及适合声波检测信号的最优小波基。(2)声波检测信号本质上是一个非平稳信号,声波信号经过复杂的岩土介质传播后,往往存在着各种频率成分的干扰波,干扰波的叠加为准确判断信号的首波时间带来困难。本文利用小波分析对实测声波检测信号进行降噪处理,在一定程度上降低了噪声信号对波形初至点判读的影响,从而提高了检测准确度。(3)根据岩石声波检测信号的原理,声波在介质中传播时,首先要受到介质的吸收和散射而引起的衰减,其次在不同介质中的分界面要发生折射和反射。由于不同介质衰减系数的不同及不同界面折射波和反射波的路径不同,声波信号的所含的频率成分不同。本文利用最优小波基将岩石声波测试信号分解成不同频带通道的小波分量,并对其第三层低频重构信号进行频谱特征分析,提取主频、最大振幅、相位谱等参数。通过对不同岩体质量的声波检测信号进行频谱分析发现,声波信号的动力学参数(能量、主频、相位)能够很好的反映出岩石中的软弱夹层及节理、裂隙的位置。结合波速值进行多参数综合分析能有效提高解释的可靠性和准确性。更多还原

【Abstract】 Acoustic detection technology based on elastic wave propagation theory, the main research acoustic propagation law and in the rocks formed by structure surface acoustic wave impedance interface, the influence of communication engineering geological evaluation, especially for the stability evaluation to provide important basis. Present acoustic detection technology, mainly using rock, its kinematics characteristic parameters, the longitudinal velocity to use less dynamic characteristics.In order to further waves of various parameters on the comprehensive analysis, this paper selects a hydropower station, using acoustic signals measured area and the programming of Matlab software for the wavelet time-frequency analysis, this study results:(1) of acoustic detection signal wavelet decomposition and reconstruction, the low frequency noise reconstruct signal analysis, through a series of signal-to-noise evaluation standard to confirm the best decomposition layers and suitable for the optimal acoustic detection signal wavelet base.(2) acoustic detection signal is essentially a the non-stationary signal, acoustic signals through complex geotechnical media, there are various frequency interference wave, the composition of the interference of the signal superimposed for accurate judgement of the first time difficult. Using the wavelet analysis of measurement noise acoustic detection signal processing in a certain extent, reduces the noise signal waveform and interpretation of early, so as to improve the accuracy of the test.(3) according to the principle of the ultrasonic detection signal, the waves in the medium, the first by the media and absorption and scattering of attenuation, secondly in different medium refraction and will happen boundary. Due to the different medium attenuation coefficient of different and different interface refraction wave and reflection wave, acoustic signals of different paths of different frequencies. Using the optimum wavelet decomposition of rock sound test signals into different frequency channel wavelet vectors, and on the third floor frequency spectrum signal reconstruction result analysis, extraction, the maximum amplitude, phase spectral parameters.Based on different rock mass of acoustic detection signal spectrum analysis, acoustic signals that the dynamic parameters (energy, contents, phase) can be very good reflects the weak layers of rock joints and fractures and position. Combining velocity value of multi-parameter comprehensive analysis can effectively improve the accuracy and reliability of the explanation.更多还原