【作者】 张立；

【导师】 刘争平；

【作者基本信息】 西南交通大学 ， 地球探测与信息技术， 2009， 博士

【摘要】 由于瑞利(Rayleigh)面波波速与横波波速Vs相近且具有速度频散等运动学特性,而被广泛应用于各种地下调查领域,如天然地震研究领域、石油地震勘探领域。近年来,随着计算机技术的飞速发展及工程勘察的需要,人工激发的瞬态瑞利面波法广泛应用于大型土木工程和环境地质方面,如场地分层,岩溶洞穴分布范围勘查,以及在建筑工程的抗震设计等。传统对瑞利面波的研究和应用主要是对主动源瑞利面波速度频散特征(运动学特征)的研究和应用。速度频散曲线的提取方法主要是利用频率-波数(F-K)变换或慢度-频率(P-F)变换。为提取速度频散曲线,需要在观测时布置较多个数的检波器和较长的排列,且勘探深度与排列尺度成正比。因此,以观测速度频散特征(运动学特征)为主的传统瑞利面波法,在具体应用中容易受场地等限制,如不适合于人口稠密、空间狭小的城市地区。为了解决传统瑞利面波法在实际应用中遇到的困难,探索面波应用的新基理,应从面波的基础理论着手,加强对瑞利面波动力学特征的研究。1989年,Nakamura提出了被动源面波地脉动信息的单点谱比法——H／V谱比(HVSR,面波水平分量与垂直分量的频谱比)法,2004年,H.Arai和K.Tokimatsu利用地脉动H／V谱比对场地Vs结构成功进行反演。该方法利用的则是面波的动力学特征,但是,由于被动源面波法地脉动信息所包含波的主要成分一直具有争议,并且地脉动信息的场源具有随机性和复杂性,使得对地脉动随机波场的正演数值模拟和理论研究仍不完备。根据以上所述,从解决传统瑞利面波法应用瓶颈问题出发,本论文提出了两种解决途径,其一,提出了采用少量检波器和短排列方式采集瑞利面波的方法,为此展开了对水平层状介质中瑞利面波波场运动学特征(速度频散特征)的正演数值模拟,讨论了利用窄带滤波或小波包滤波及互相关计算从短排列信号中提取瑞利面波速度频散曲线的方法,以及研究了利用瑞利面波运动学特征对地层Vs结构进行反演的方法；其二,结合地脉动单点谱比法的优缺点,本论文考虑利用主要成分容易确定的人工激发的主动源瑞利面波,即提出了利用单个三分量检波器采集的主动源瑞利面波信息的HVSR(动力学特征)对地层Vs结构进行反演的方法,并围绕该核心内容展开了对水平层状介质中瑞利面波波场动力学特征的正演数值模拟,以及利用瑞利面波动力学特征对地层Vs结构进行反演的方法研究。其中,重点是对瑞利面波动力学特征的研究。在对瑞利面波动力学特征的研究过程中,一方面是对主动源瑞利面波HVSR法的物理机制——椭圆极化特征随频率变化规律的数值模拟研究,研究结果表明,瑞利面波椭圆极化特征与地层Vs结构之间具有良好的对应关系,并创新性的提出了椭圆极化频散的概念,该研究结果奠定了利用主动源瑞利面波动力学特性——HVSR对地层Vs结构进行反演的正演理论基础；另一方面是对利用主动源瑞利面波HVSR特性对地层Vs结构反演的方法研究,研究结果表明,利用主动源瑞利面波动力学特性——HVSR特性能够成功对地层Vs结构进行反演。通过以上对水平层状介质中瑞利面波波场特征(运动学和动力学特征)的正演数值模拟研究,以及对利用瑞利面波波场特征(运动学和动力学特征)对地层Vs结构进行反演的研究,本文实现了所有正演及反演算法及其所对应的MATLAB语言程序,并结合工程实例,验证了所有算法及程序的可行性和稳定性。本论文研究内容及成果解决了传统瑞利面波法所遇到的场地限制等问题,对于扩展瑞利面波在工程中的应用范围提供了更加完备的基础理论,对相关的工程设计和建筑抗震设计等都具有重要的研究意义,对于完善该学科理论,促进学科发展有极大帮助。更多还原

【Abstract】 Because of the dispersion characteristic and the similarity of velocity to shear wave, Rayleigh surface wave is widely used in various kinds of underground investigation areas, such as the natural earthquake research, oil seismic exploration, etc. In recent years, along with the rapidly development of computer technology and the need of engineering investigation, transient Rayleigh surface wave method with artificial excitation has been popularized in large civil engineering and environmental geology, such as medium stratification, karst cave distribution range investigation and antiseismic design for building engineering.Traditional research and application of Rayleigh surface wave method is based on its velocity dispersion characteristic (kinematic characteristic).The dispersion curve is usually extracted with the method of F-K domain filtering which needs to arrange many geophones and long array during observation, and the exploration depth is proportional to the length of the array. So, the traditional Rayleigh surface wave method is obviously limited to the space of the site, for example, it can not suitable for urban area with dense population and small spaces.To solve the application difficulties of the traditional Rayleigh surface wave method, we should exploration new theory with strengthening the research of dynamic characteristic of surface wave on the basic theory. In 1989, Nakamura proposed the H/V spectral ratio method (horizontal to vertical spectral ratio, HVSR) for micro-tremor information with passive source. In 2004, H.Arai and K.Tokimatsu successfully achieved the medium Vs structure by using the HVSR method of micro-tremor. The HVSR method is based on the dynamic characteristic of surface wave. Because of the essential component uncertainty and the randomicity and complexity of micro-tremor information with passive source, the forward numerical simulation of the micro-tremor wave-field is still incomplete till this day.In this dissertation, in order to solve the application difficulties in small site spaces limitation for the traditional surface wave method, it puts forward two approaches of inversion. The first is acquiring Rayleigh surface wave with fewer geophones and shorter array. To carry out this approach, the kinematic characteristic (verlocity dispersion characteristic) of Rayleigh surface wave field has been studied using numerical simulation, and the method of narrowband pass filtering and wavelet packet filtering have been discussed in this dissertation, which are used to extract the dispersion curve from time domain signial with shorter array. The second is using the HVSR characteristic (dynamic characteristic) of active source Rayleigh surface wave information acquired with single three-component geophone, combined with the advantages and disadvantages of micro-tremor HVSR method. Around this content, it studies not only dynamic characteristic of Rayleigh surface wave field with active source using numerical simulation method, but also the inversion method with the dynamic characteristic. About the two approaches, the second one dealt wth the dynamic characteristic of Rayleigh surface wave is mainly studied in the dissertation, and it is studied on two hands. On the one hand, the study is on the elliptic polarization characteristics of Rayleigh surface wave and the concept of elliptic polarization dispersion is put forword creatively, which is the physical mechanism for active source HVSR method, and the result of which shows that it has good corresponding relationship between the medium Vs structure and the elliptic polarization characteristics; on the other hand, the study is on the inversion method with using the HVSR characteristic, the dynamic characteristic of Rayleigh surface wave, the result of which shows that the medium Vs structure can be successfully achieved by inversion with the HVSR characteristic of Rayleigh surface wave with active source.Through the research of Rayleigh surface wave field characteristic (kinematic and dynamic characteristic) by numerical simulating for horizontal layered medium and the research of medium Vs structure inversion by using the field characteristic, the dissertation has realized not only the forward and inversion algorithms, but also the corresponding MATLAB language programs. Combined with the practical work, it is has been verified that the algorithms and programs is feasible and stable.The research results of this dissertation can successfully solve the application difficulties of the traditional Rayleigh surface wave method. It provides more perfect basic theory for expanding the applicable range in engineering. It not only has important research meanings for antiseismic design of building engineering, but also is very helpful for improving the scientific theory and promoting the development of the subject.更多还原