被动源瑞利波两道法提取频散曲线的质量控制方法  

A study of quality control of extracting dispersion curves by two-channel method of passive Rayleigh waves

作　　者：邵广周[1] 岳亮[1] 李远林 吴华[2] SHAO Guang-Zhou;YUE Liang;LI Yuan-Lin;WU Hua(School of Geological Engineering and Geomatics,Chang'an University,Xi'an 710054,China;School of Science,Chang'an University,Xi'an 710064,China)

机构地区：[1]长安大学地质工程与测绘学院,陕西西安710054 [2]长安大学理学院,陕西西安710064

出　　处：《物探与化探》2019年第6期1297-1308,共12页Geophysical and Geochemical Exploration

基　　金：国家自然科学基金项目(41874123,41004043);陕西省自然科学基金项目(2016JM4003);长安大学中央高校基金项目(300102268402,300102129111);中国地质调查局地质调查项目(DD20160060)

摘　　要：近年来,迅速发展起来的被动源瑞利波勘探技术将环境噪声当做信号源,具有抗干扰能力强、施工条件受限少等优点,更适合于城市周边等地区的勘探工作。而影响被动源方法成像精度的关键因素是频散曲线的提取质量。当前被动源瑞利波法主要根据空间自相关与时域互相关之间的联系,利用Aki公式计算瑞利波频散曲线。该方法对于长周期观测数据(连续几个月以上)具有较好的提取效果,但对于实际工程应用来说,希望数据观测周期越短越好(如一天或几个小时),此时利用Aki法拾取频谱实部曲线零点时,互相关函数频谱会出现零点增多或缺失的现象,导致频散曲线的提取出现误差。文中针对这一问题,通过采用不同的归一化方法、选择不同的时窗长度进行互相关、设置高斯滤波器对互相关函数进行滤波以及筛选频谱零点的处理方法,结合均方误差、相关系数以及信噪比验证频散曲线的可靠性,来控制频散曲线的质量。通过理论模型被动源数值模拟结果试算和陕西凤翔县野外实际噪声数据处理,验证了本文频散曲线质量控制方法的可行性和有效性,对被动源瑞利波法频散曲线提取具有一定的参考价值和实际意义。In recent years,the rapidly developed passive Rayleigh wave technology has the advantage of strong anti?interference capabil?ity and less limited construction conditions by using environmental noise as the source,which is more suitable for exploration in urban areas.However,the key factor affecting the imaging accuracy of the passive source method is the extracting quality of the dispersion curves.The current passive source Rayleigh wave method mainly uses the Aki formula to calculate the Rayleigh wave dispersion curve according to the relationship between spatial autocorrelation and time domain cross?correlation.This method has a good extraction effect for long?period observation data(for several months or more).Nevertheless,for practical engineering applications,it is desirable that the data observation period is as short as possible(such as one day or several hours).Under this circumstance,it will lead the zero points of the cross?correlation spectrum to increase or disappear,which will bring errors in the extraction of the dispersion curves when the Aki method is used to pick up them.Aimed at solving this problem,the authors put forward a set of quality control processes,such as using different normalization methods,selecting different window lengths for cross?correlation operations,setting Gaussian filters to filter cross?correlation functions,and selecting spectral zeros,to improve the extracting quality of dispersion curves.The authors combined certain e?valuation criteria to verify the reliability of the dispersion curves and achieved the purpose of controlling the quality of the dispersion curves extraction.The passive source numerical simulation of theoretical model testing and the actual field noise data processing in Fengxiang County of Shaanxi show that the quality control method in the dispersion curve extraction is feasible and effective.This study has certain reference value and practical significance for the dispersion curve extraction of passive source Rayleigh wave method.

关 键 词：瑞利波 频散曲线 被动源地震 质量控制 

分 类 号：P631.4[天文地球—地质矿产勘探]