脉冲压缩方法检测岩石弹性波速度
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摘要
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。
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.
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.
引文
[1]金振民,欧新功,徐海军,等.中国大陆科学钻探主孔
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[6]彭苏萍,谢和平,何满潮,等.沉积相变岩体声波速度特征的试验研究[J].岩石力学与工程报,2005,24(16):2831-2837.PENG Su-ping,XIE He-ping,HE Man-chao,et al.Experimental study on velocity characteristics oflithofacies transition rock mass[J].Chinese Journal ofRock Mechanics and Engineering,2005,24(16):2831-2837.
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[12]彭旗宇,高上凯.医学超声成像中的编码激励技术及其应用[J].生物医学工程学杂志,2005,22(1):175-180.PENG Qi-yu,GAO Shang-kai.Coded excitation and itsapplications in medical ultrasound imaging[J].Journal ofBiomedical Engineering,2005,22(1):175-180.
[13]韩雪梅,彭虎.基于线性调频信号的高帧率超声成像系统[J].中国生物医学工程学报,2005,24(6):700-704.HAN Xue-mei,PENG Hu.High frame rate ultrasonicimaging system based-on linear frequency modulatedsignal[J].Chinese Journal of Biomedical Engineering,2005,24(6):700-704.
[14]蒲诚,张涛,綦磊.不同编码激励的超声气体流量测量性能对比[J].天津大学学报,2011,44(9):768-773.PU Cheng,ZHANG Tao,QI Lei.Performancecomparison of ultrasonic gas flow metering systems withdifferent coded excitations[J].Journal of TianjinUniversity,2011,44(9):768-773.
[15]周正干,魏东,向上.线性调频脉冲压缩方法在空气超声检测中的应用研究[J].机械工程学报,2010,46(18):24-35.ZHOU Zheng-gan,WEI Dong,XIANG Shang.Applica-tion of linear-frequency——Modulation based pulsecompression in air-coupled ultrasonic testing[J].Journalof Mechanical Engineering,2010,46(18):24-35.
100～2000m岩石弹性波速度:对地震深反射的约束[J].岩石学报,2004,20(1):81-96.JIN Zhen-min,OU Xin-gong,XU Hai-jun,et al.Elasticwave velocities of the 2 000 m depth at Chinese Con-tinental Scientific Drilling:Constraints on deep seismicreflection[J].Acta Petrologica Sinica,2004,20(1):81-96.
[2]赵志丹,高山,骆庭川.秦岭和华北地区地壳低速层的成因探讨-岩石高温高压波速试验证据[J].地球物理学报,1996,36(5):642-652.ZHAO Zhi-dan,GAO Shan,LUO Ting-chuan.Origin ofthe crustal low velocity layer of Qinling and North Chinaevidence from laboratory measurement of P-wavevelocity in rocks at high PT conditions[J].ChineseJournal of Geophysics,1996,36(5):642-652.
[3]孟召平,张吉昌,JOACHIM Tiedemann.煤系岩石物理力学参数与声波速度之间的关系[J].地球物理学报,2006,49(5):1505-1510.MENG Zhao-pin,ZHANG Ji-chang,JOACHIMTiedemann.Relationship between physical andmechanical parameters and acoustic wave velocity of coalmeasures rocks[J].Chinese Journal of Geophysics,2006,49(5):1505-1510.
[4]曹获.层析成像二阶段射线追踪技术在工程中的应用[J].岩土力学,2005,26(7):1157-1160.CAO Huo.Application of computerized tomography two-phase ray tracing technique to civil engineering[J].Rockand Soil Mechanics,2005,26(7):1157-1160.
[5]张永乐,唐德高.超声波层析成像在桩身结构完整性诊断中的应用[J].岩土力学,2009,30(11):3548-3552.ZHANG Yong-le,TANG De-gao.Application ofultrasonic computerized tomography to diagnosis of pileconstruction integrity[J].Rock and Soil Mechanics,2009,30(11):3548-3552.
[6]彭苏萍,谢和平,何满潮,等.沉积相变岩体声波速度特征的试验研究[J].岩石力学与工程报,2005,24(16):2831-2837.PENG Su-ping,XIE He-ping,HE Man-chao,et al.Experimental study on velocity characteristics oflithofacies transition rock mass[J].Chinese Journal ofRock Mechanics and Engineering,2005,24(16):2831-2837.
[7]皮亦鸣.合成孔径雷达成像原理[M].成都:电子科技大学出版社,2007.
[8]赵树杰.雷达信号处理技术[M].北京:清华大学出版社,2010.
[9]张娟,张林让,徐青,等.基于多级维纳滤波的MIMO雷达自适应脉冲压缩方法[J].电子与信息学报,2010,32(5):1045-1049.ZHANG Juan,ZHANG Lin-rang,XU Qing,et al.Adaptive pulse compression of MIMO Radar based onMSWF[J].Journal of Electronics&InformationTechnology,2010,32(5):1045-1049.
[10]SIMON T,JEAN-FRANCOIS S,CHRISTINE E M,et al.Low-voltage coded excitation utilizing a miniaturizedintegrated ultrasound system employing piezoelectric 2-Darrays[J].IEEE Transactions on UltrasonicsFerroelectrics and Frequency Control,2010,57(2):353-362.
[11]孙超.水下多传感器阵列信号处理[M].西安:西北工业大学出版社,2007.
[12]彭旗宇,高上凯.医学超声成像中的编码激励技术及其应用[J].生物医学工程学杂志,2005,22(1):175-180.PENG Qi-yu,GAO Shang-kai.Coded excitation and itsapplications in medical ultrasound imaging[J].Journal ofBiomedical Engineering,2005,22(1):175-180.
[13]韩雪梅,彭虎.基于线性调频信号的高帧率超声成像系统[J].中国生物医学工程学报,2005,24(6):700-704.HAN Xue-mei,PENG Hu.High frame rate ultrasonicimaging system based-on linear frequency modulatedsignal[J].Chinese Journal of Biomedical Engineering,2005,24(6):700-704.
[14]蒲诚,张涛,綦磊.不同编码激励的超声气体流量测量性能对比[J].天津大学学报,2011,44(9):768-773.PU Cheng,ZHANG Tao,QI Lei.Performancecomparison of ultrasonic gas flow metering systems withdifferent coded excitations[J].Journal of TianjinUniversity,2011,44(9):768-773.
[15]周正干,魏东,向上.线性调频脉冲压缩方法在空气超声检测中的应用研究[J].机械工程学报,2010,46(18):24-35.ZHOU Zheng-gan,WEI Dong,XIANG Shang.Applica-tion of linear-frequency——Modulation based pulsecompression in air-coupled ultrasonic testing[J].Journalof Mechanical Engineering,2010,46(18):24-35.
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