【作者】 谢忠球；

【导师】 温佩琳；

【作者基本信息】 中南大学 ， 地球探测与信息技术， 2002， 博士

【摘要】 场地微动的观测研究应用于场地地震反应分析，可以表征场地地震动特性的某些参数，是确定场地动力特性、预测场地的地震动影响特性和建筑物抗震能力调查的一种非常方便、非常重要的手段。 目前，场地微动的理论研究与工程应用基本上是基于各向同性(包括覆盖土层和基岩各向同性)的假设前提。事实上，场地土往往具有各向异性。从弹性波理论出发，分析土介质各向异性及其对场地微动、场地动力特性的影响，开展各向异性介质中的场地微动理论及应用研究具有重要的理论意义和实际应用价值，选题具有先进性。 从各向异性介质的弹性波理论出发，本文系统地分析了各向异性土介质中地震波的传播特性。由于土介质的波速度存在各向异性，波速测试的方法及波型的选抒对测试结果有显著影响。目前单一的测试方法获得的速度信息不能全面反映场地的动力特性，从而影响场地地震反应分析结果，因而场地速度测试与分析中考虑各向异性是必要的。 首次对各向异性土介质中的场地微动进行了数值模拟研究，分析了入射波频率对场地微动的影响以及场地动力特性随着深度的变化特征。在理论分析和数值模拟的基础上，研究了各向异性介质的场地微动机制。从弹性波理论、土动力学及场地地震反应分析理论出发，首次提出了场地微动主轴概念，分析了各向异性场地微动与土动力学参数之间的关系；系统地研究了各向异性主轴的确定和分析方法。这一首次系统研究为各向异性场地地震反应分析提供了理论基础。 本文研究了土介质的各向异性对土动力特性的影响，研究了场地微动对土体稳定性的影响及其与各向异性主轴的关系。考虑卓越周期对地震反应的影响，在工程结构的抗震设计中，提出对结构主要自振周期的禁区约束处理应充分考虑场地卓越周期的各向异性影响的思想，分析了卓越周期计算和禁区约束处理方法，同时对各向异性场地微动观测和分析处理技术进行了研究。各向异性介质中的场地微动理论与应用研究，具有一定的创新性。 对目前场地分类方法进行了初步分析，提出场地分类应考虑反应谱的各向异性，以及利用场地微动各向异性特征的分类思想和方法。考虑结构的复杂性和输入地震包括多维地震及各向异性影响的重要性，提出了利用场地微动的各向异性特征参数作为多维输入地震选择和调整参考因子的初步想法和实现方法。 本文仅仅研究了覆盖土层各向异性对场地微动的影响。实际上，场地介质对场地微动的影响还包括覆盖层的非均匀性、基岩的非均匀性及其各向异性等因素，这些都有待下一步研究。更多还原

【Abstract】 The study of ground microtremor can be applied to analysis on the response of ground seismic, characterization of some speciality of ground seismic. It’s one of the most important and convenient methods for determining the dynamic properties of the soil , predicting the characteristics of ground seismic, and studying of the shock resistance of the architecture.At present, the study of theory and the engineering application on ground microtremor are based on the hypothesis of isotropy basically. In fact, the characteristic of the soil is usually anisotropy. It is important and useful to study the theory and the application of ground microtremor in the anisotropy soil, influence of the anisotropy to the ground microtremor, the dynamic properties of the ground based on the theory of elastic wave. This is one of the leading topic in the area of the seismology .Based on the theory of elastic wave in anisotropy medium, the characteristic of the seismic wave is analyzed in this paper. Wave field in anisotropy medium is quite different from that of in isotropy medium. As the influence of the characteristic of anisotropy, the wave modes and the surveying method have important effect on the results of the velocity, then the velocity will affect the calculation of the fundamental period. Therefore, considering the anisotropy in study and analysis of the ground velocity testing is necessary.In this paper, the characteristics of the ground microtremor in anisotropy soil, the influence of the frequency of the incident wave to the characteristics of the ground microtremor, and the variation of the ground characteristics with depth have been studied. The mechanism of the ground microtremor has been studied based on the analysis of theory and numerical modeling. The conception of the principal axis has been put forward. The method for determining of the principal axis has been studied systematically in this article. This study make up the foundation of the analysis of the ground response.The effect of the anisotropy to the soil dynamics has been studied in this article. The effects of ground microtremor to the stability of the soil, and the relationship to the stability of the soil and principal axis have also been studied. Taking account of the effect of the fundamentally period to the ground response, the design of seismic structures considering structural vibration period restraint should respect the influence of the anisotropy of the fundamental period. A method considering fundamentalperiod of the principal axis for the structural vibration period restraint has been put forward. The observation measurement and processing technique with wavelet have been studied.The method of the soil category is analyzed in this paper. Method for the classification of soil considering the characteristics of anisotropy of the ground microtremor , and method for the selection of the earthquake time history considering anisotropy are put forward respecting to the ground microtremor.In this paper, only the effect of the anisotropy of the earth covering was considered. In fact characteristics of the soil including the heterogeneity of the earth covering, the heterogeneity and the anisotropy of the base rock are also important factors that affect the characteristics of the ground microtremor. All of these will be studied further in the future.更多还原