基于SPAC和NCF技术的被动源面波浅勘方法研究
发布时间：2018-11-19 08:55
【摘要】：工程场地剪切波速度结构是场地分类的重要参数,在国际上多用30米深度内的平均剪切波速(Vs30)作为场地分类标准,国内以覆盖土层厚度和20米深度内的等效剪切波速作为场地分类标准。土层的剪切波速度结构也是进行场地地震反应分析计算中的必须参数。因此,在工程勘察中剪切波速度结构的测试尤为重要。目前,对场地剪切波速的勘察主要有钻孔直接测试法和面波测试法,其中钻孔法结果直观、可靠,但经济成本高,且是一种破坏性的勘察方法,不易大面积开展；面波法以其无损性、经济快速的优点,成为场地普查的一种快捷方法,在浅勘领域获得广泛应用。本文在回顾分层介质中面波的传播理论、主动源和被动源面波浅勘方法(主要是基于微动信息的空间自相关技术,SPAC,SPatial AutoCorrelation;地震背景噪声互相关成像技术,NCF, ambient Noise Correlation Function)的基础上,基于SPAC和NCF物理基础的一致性,提出将主动源面波浅勘,传统的微动SPAC方法和NCF方法联合用于小尺度面波浅勘领域,并尝试将大尺度三维面波成像技术引入到小尺度面波勘探中,实现面波浅勘的三维成像。针对研究目的和设想,在云南省玉溪某地设计了一个直径为16米,包含有23个垂直单分量检波器的圆形台阵,进行了主动源和被动源面波观测的试验研究。对于SPAC方法,设计了一种特殊点约束技术从空间自相关系数中提取频散曲线的方法,并提取了6.7-23Hz频段可靠的频散曲线,通过对该观测的频散曲线与预测模型的频散曲线进行拟合,反演得到S波速度结构,并与钻孔测试结果吻合；对于NCF技术,通过互相关计算,获得了不同路径的时域互相关函数,对质量较高的互相关函数提取了群速度频散曲线,并获得了不同路径的频散特征；对主动源记录,采用表面波谱分析技术(SASW)获得了不同路径的频散曲线；以SPAC的一维反演结果作为初始模型,对NCF和SASW获得的频散曲线进行了反演,得到了不同路径,不同深度的S波速度结构,初步实现了面波浅勘的三维速度成像。
[Abstract]:The shear wave velocity structure is an important parameter in site classification. The average shear wave velocity (Vs30) in the depth of 30 meters is used as the standard of site classification in the world. In China, the equivalent shear wave velocity within 20 m depth and the thickness of overlying soil layer are taken as the site classification criteria. The shear wave velocity structure of soil layer is also a necessary parameter in the analysis and calculation of site seismic response. Therefore, it is very important to test the shear wave velocity structure in engineering survey. At present, the investigation of the shear wave velocity of the site mainly includes drilling direct testing method and surface wave testing method. The results of drilling method are intuitive and reliable, but the economic cost is high, and it is a destructive survey method, which is not easy to carry out in a large area. Because of its advantages of nondestructive and rapid economy, surface wave method has been widely used in the field of shallow prospecting. In this paper, the propagation theory of surface waves in layered media, the shallow prospecting methods of active and passive surface waves (mainly spatial autocorrelation based on fretting information, SPAC,SPatial AutoCorrelation;) are reviewed. Based on the seismic background noise cross-correlation imaging technique, NCF, ambient Noise Correlation Function) and the consistency of the physical basis of SPAC and NCF, it is proposed that the active source surface wave shallow prospecting, the traditional fretting SPAC method and the NCF method be used in the field of small scale surface wave shallow prospecting. The large scale 3D surface wave imaging technology is introduced into the small scale surface wave exploration to realize the 3D imaging of surface wave shallow prospecting. A circular array with a diameter of 16 meters and 23 vertical single-component geophones was designed in a certain area of Yuxi Yunnan Province for the purpose and assumption of the research. The experimental study of active and passive source surface wave observation was carried out. For the SPAC method, a special point constraint technique is designed to extract the dispersion curve from the spatial autocorrelation coefficient, and the reliable dispersion curve in the 6.7-23Hz band is extracted. By fitting the observed dispersion curve with the dispersion curve of the prediction model, the S-wave velocity structure is obtained by inversion, and the results are in good agreement with the borehole test results. For NCF technology, the time-domain cross-correlation function of different paths is obtained by cross-correlation calculation, and the dispersion curve of group velocity is extracted for the high-quality cross-correlation function, and the dispersion characteristics of different paths are obtained. For active source records, the dispersion curves of different paths are obtained by surface spectrum analysis (SASW). Using the one-dimensional inversion results of SPAC as the initial model, the dispersion curves obtained by NCF and SASW are inversed. The S-wave velocity structures with different paths and depths are obtained, and the 3-D velocity imaging of shallow surface waves is preliminarily realized.
【学位授予单位】：中国地震局地球物理研究所
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.4
本文编号：2341780
[Abstract]:The shear wave velocity structure is an important parameter in site classification. The average shear wave velocity (Vs30) in the depth of 30 meters is used as the standard of site classification in the world. In China, the equivalent shear wave velocity within 20 m depth and the thickness of overlying soil layer are taken as the site classification criteria. The shear wave velocity structure of soil layer is also a necessary parameter in the analysis and calculation of site seismic response. Therefore, it is very important to test the shear wave velocity structure in engineering survey. At present, the investigation of the shear wave velocity of the site mainly includes drilling direct testing method and surface wave testing method. The results of drilling method are intuitive and reliable, but the economic cost is high, and it is a destructive survey method, which is not easy to carry out in a large area. Because of its advantages of nondestructive and rapid economy, surface wave method has been widely used in the field of shallow prospecting. In this paper, the propagation theory of surface waves in layered media, the shallow prospecting methods of active and passive surface waves (mainly spatial autocorrelation based on fretting information, SPAC,SPatial AutoCorrelation;) are reviewed. Based on the seismic background noise cross-correlation imaging technique, NCF, ambient Noise Correlation Function) and the consistency of the physical basis of SPAC and NCF, it is proposed that the active source surface wave shallow prospecting, the traditional fretting SPAC method and the NCF method be used in the field of small scale surface wave shallow prospecting. The large scale 3D surface wave imaging technology is introduced into the small scale surface wave exploration to realize the 3D imaging of surface wave shallow prospecting. A circular array with a diameter of 16 meters and 23 vertical single-component geophones was designed in a certain area of Yuxi Yunnan Province for the purpose and assumption of the research. The experimental study of active and passive source surface wave observation was carried out. For the SPAC method, a special point constraint technique is designed to extract the dispersion curve from the spatial autocorrelation coefficient, and the reliable dispersion curve in the 6.7-23Hz band is extracted. By fitting the observed dispersion curve with the dispersion curve of the prediction model, the S-wave velocity structure is obtained by inversion, and the results are in good agreement with the borehole test results. For NCF technology, the time-domain cross-correlation function of different paths is obtained by cross-correlation calculation, and the dispersion curve of group velocity is extracted for the high-quality cross-correlation function, and the dispersion characteristics of different paths are obtained. For active source records, the dispersion curves of different paths are obtained by surface spectrum analysis (SASW). Using the one-dimensional inversion results of SPAC as the initial model, the dispersion curves obtained by NCF and SASW are inversed. The S-wave velocity structures with different paths and depths are obtained, and the 3-D velocity imaging of shallow surface waves is preliminarily realized.
【学位授予单位】：中国地震局地球物理研究所
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.4
【参考文献】
相关期刊论文 前3条
1 鲁来玉;张碧星;汪承灏;;基于瑞利波高阶模式反演的实验研究[J];地球物理学报;2006年04期
2 徐佩芬;李传金;凌u&群;张胤彬;侯超;孙勇军;;利用微动勘察方法探测煤矿陷落柱[J];地球物理学报;2009年07期
3 单娜琳;刘占兴;;分离高阶模态面波的τ-p变换方法[J];桂林理工大学学报;2013年03期
，本文编号：2341780
本文链接：https://www.wllwen.com/kejilunwen/diqiudizhi/2341780.html
