摘要
囿于波动问题空间采样率观念的限制,现有多道瞬态瑞雷波探测方法采用小道间距、多道检波器排列方式观测同一次激发的瞬态瑞雷波,虽然解决了同时观测不同频率成分波动的问题,但一个排列的多道检波器只能得到一条瑞雷波相速度-探测深度曲线,工作效率和横向分辨力受到极大限制,同时,所能够提取的最高频率波动成分也受到了检波器排列最小道间距的限制.经分析发现,忽略两个测点之间瞬态瑞雷波到时差对不同频率波动道间相位差的影响是上述问题的根源.针对现有多道瞬态瑞雷波探测方法的弱点,本文阐明了道间时差相位(TDP)的概念和意义,提出了考虑道间时差相位的测点对间相位差分析技术,形成了一套新的多道瞬态瑞雷波探测方法——TDP法. TDP法摆脱了最小道间距的羁绊,只用两道检波器的瞬态瑞雷波记录即可提取多种频率成分波动的相速度,完成现有方法一个多道检波器排列才能完成的工作,探测工作效率大大提高;同时,根据场地岩土体的横向变化适当调整检波器布置的测点间距,在一条测线上布置多个测点,相邻测点对两两组合获得的多条瑞雷波相速度-深度曲线可以反映岩土体横向变化,这使得探测方法的横向分辨力显著提高;另外,由于引进道间时差相位,高频成分的提取不再受道间距的控制,从而探测方法的高频分辨力也得到了大幅度提高,原则上,激发和测试系统能够产生和记录到的高频成分新方法都可以提取到,事实上,这套方法已经成功地拓展到了超声频段的探测工作中.
Limited by the concept of spatial sampling rate in wave problems,multichannel detector array with small channel spacing is adopted to observe the transient Rayleigh wave excited by an impulse action. The method does put forward an approach to the observation of different frequency components of transient Rayleigh wave at once,but it can only get one curve of the relationship between phase velocities and effective detecting depths from the detector array covering a certain length of a detecting line with many detecting points. This is doomed to result in three defects of the method: low efficiency of operation,weak lateral resolving power and limited high frequency resolving power,and the last one is mainly owing to the limitation of the smallest distance between channels. It is found after carefully analysis that the source of the defects is overlooking the contribution of the time difference of transient Rayleigh waves to the phase differences of different frequency wave components between two detecting channels. In order to overcome the defects of the existing transient Rayleigh wave detecting method with multichannel detectors,the concept of Arrival Time Difference Phase between Channels( or TDP for short) and its significance are expounded in this paper,and the analysis method of the phase difference between a pair of detecting points in consideration of TDP of different frequency wave components is put forward,as a result, a new transient Rayleigh wave detecting method with multichannel detectors—the TDP Method—is formed.Getting rid of the fetter of required smallest distance between channels,the new method is able to extract the phase velocities ofdifferent frequency wave components with only two waveforms of transient Rayleigh waves recorded on two detecting points,which used to be the work with a multichannel detector array,therefore,the efficiency of the new method is greatly enhanced;in addition,with proper distances between channels fitting to the lateral changes in features of rock or soil masses
作者
刘磊
周富彪
孙进忠
李高
祁生文
何华
陈祥
田小甫
LIULei;ZHOUFu-biao;SUNJin-zhong;LIGao;QISheng-wen;HEHua;CHENXiang;TIANXiao-fu(China Institute of Geotechnical Investigation and Surveying Company Limited,Beijing 100007,China;Institute of Karst Geology,CAGS,Guangxi Guilin 541004,China;School of Engineering and Technology,China University of Geosciences,Beijing 100083,China;Beijing Dongcheng Vibration Engineering Society,Beijing 100007,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Beijing Gonglian Highway Connection Line Company Limited,Beijing 100161,China;School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China;Beijing Institute of Geological and Prospecting Engineering,Beijing 100048,China)
出处
《地球物理学进展》
CSCD
北大核心
2019年第1期331-341,共11页
Progress in Geophysics
关键词
瞬态瑞雷波
道间时差相位(TDP)
相速度
有效探测深度
多道探测方法
TDP法
Transient Rayleigh wave
Arrival Time Difference Phase between Channels(TDP)
Phase velocity
Effective detecting depth
Detecting method with multichannel detectors
The TDP method
