脉冲压缩方法检测岩石弹性波速度

针对岩石弹性波速度检测信噪比低、回波信号初至时间不易判读，以及较长岩石（或混凝土）超声检测难以穿透问题，提出用脉冲压缩方法检测弹性波速度。该方法与超声脉冲法检测的不同之处是在发射端采用编码信号激励，在接收端进行匹配滤波，得到高信噪比的压缩信号。介绍线性调频信号的宽时宽带特性，分析了脉冲压缩的基本原理和数字实现过程。试验研究了换能器带宽对激发信号的影响。用常规的单脉冲法和脉冲压缩方法检测了多个岩样的弹性波速度，试验结果表明，两种检测结果差异较小。给出了脉冲压缩方法用于岩石弹性波速度检测的具体步骤和计算过程。综合分析，脉冲压缩方法检测岩石弹性波速度是可行的，能够用于岩土工程的质量评价。

Elastic wave velocity inspection for rocks by pulse compression method

On account of existing problems in rock elastic wave velocity inspecting, such as low signal to noise ratio(SNR), difficulty in reading the prime time of echo and inspecting large volume rock, pulse compression method is proposed. Linear frequency modulation (LFM) signal is mostly used as exciting source due to its remarkable properties, such as wide bandwidth, high energy and high SNR. While receiving terminal, echo signal is filtered by a matched filter, and the compression signal of high SNR is obtained. The wide time and band characteristics of LFM signal are introduced. In addition, the pulse compression principle and digital implementation process are also analyzed. The influence of the bandwidth of transducer on exciting signal is studied; elastic wave velocity of several rocks is inspected with a conventional method and pulse compression method. The wave velocity differences of two testing methods show a limited error. The detailed implementation and calculating process of pulse compression inspecting method are also described. The advantages and prospects of the method are analyzed. Results show that pulse compression method can be applied to inspect the elastic wave velocity in rock and access engineering quality.