【作者】 王维铭；

【导师】 袁晓铭；

【作者基本信息】 中国地震局工程力学研究所 ， 岩土工程， 2013， 博士

【摘要】 震害调查是获取工程震害资料和经验最重要的手段,也是工程抗震理论和分析方法发展的基础。工程地震学的发展离不开历次地震考察,特别是破坏性地震震害启示。我国抗震设计技术演化历程中,河源(1962)、邢台(1966)、通海(1970)、海城(1975)、唐山(1976)和汶川(2008)等大地震深入的震害调查和现场勘测,对我国工程抗震技术的发展及抗震规范的形成起到了极大的推动作用。地震液化及震害在以往历次大地震破坏中占有相当的比重,是岩土地震工程学者及工程师密切关注的课题。目前液化研究已经取得了很大进展,但从现有的成果看,离客观需求还有很大距离,特别是以实际液化调查数据分析场地液化特征以及从实际资料出发研究影响液化的因素等方面,近些年成果尚少,一定程度阻滞了岩土地震工程和土动力学的发展,主要表现在：(1)缺乏地震现场液化宏观评价的调查方法和描述标准,使得研究人员对地震中液化程度以及所造成的震害情况不能得到全面的认识；(2)国内外历次大地震中液化资料及数据缺乏系统的整理,液化数据库建设亟待解决；(3)近期国际上大地震液化实测数据分析整理不够,对实测资料中所反映液化场地特征认识不足,对国内外液化数据的差别和联系还缺乏了解,使得我国液化判别方法现状和发展方向认识不清；(4)近期大地震获取了很多宝贵的液化场地实测新数据,可以用来分析影响液化的场地特征量与液化的相关性,得到实际动荷情况、真实埋藏条件以及现场实测土力学指标与液化相关程度的真实认识,用于检验现有的液化判别方法,但以往这方面的研究成果尚少。本论文的完成的主要工作及成果如下：1.收集整理了国内外48次大地震的液化资料,建立了场地液化资料数据库,分析了包括土层埋藏条件(埋深、水位)、土性(密实度、粒径)和基本力学指标(标贯击数)等场地特征,剖析了大陆与其他地区场地特征的差别和联系,对土层液化得到了较为全面和客观的认识,修正了传统认识上的一些错误和偏差。2.鉴于震害调查工作的需求和现有规范的缺欠,通过对汶川地震实际液化考察过程中遇到问题及思考,提出了宏观液化指数和宏观液化等级的概念及划分标准,并对比国内外震害资料论证了所提出标准的可行性,为震后液化调查和震害评估提供一套便于参考的指标,也为液化研究积累可靠全面的基础资料提供了必要的手段。3.系统地整理了我国汶川Ms8.0级大地震液化震害调查资料,根据获取的汶川地震液化调查资料及现场勘探数据,采用提出的宏观液化指数和等级的划分标准,深入地剖析了汶川地震液化震害,给出了汶川地震及成都、德阳和绵阳三个主要液化区的宏观液化等级分布及震害案例分析,同时利用震害调查资料,分析了液化与非液化场地震害、宏观液化指数与地震动等之间的关系,为全面、深入了解和掌握汶川地震液化特点提供了依据。4.收集了51个国内外地震的5103例数据,利用皮氏积距相关系数法分析了PGA、水位、埋深、标贯以及波速等几个影响液化的特征参数与液化的相关性,对比分析了在不同埋深、水位和烈度范围内各参数相关性及各参数间相互关系,得到了实际动荷情况、真实埋藏条件以及现场实测土力学指标与液化关联性的真实结果,给出了大陆、台湾、欧美和日本地震中影响液化的特征参数与液化相关性的对比结果,为深化土层与地震动特征量与液化关系的认识、检验现有液化判别方法提供了支持。5.利用建立的液化数据库,采用液化数据实际相关性与公式推演数据相关性对比方法,对我国规范中SPT、CPT和Vs液化判别公式进行了检验,给出了三个液化判别方法的可靠性评价,指出我国规范CPT液化判别公式中砂层埋深符号定性的错误以及我国规范Vs液化判别公式中砂层埋深对液化判别贡献过小的问题。6.收集整理了2011年2月22日新西兰Christchurch地震中液化数据,分析了液化场地的特征,并利用相关性理论研究了砂层埋深和水位、标准贯入击数和地震强度等特征参数与液化的相关性,得到新西兰地震液化较为全面和客观的认识,同时分析了新西兰地震与国内外其它地震场地特征与液化相关性的差异和联系。更多还原

【Abstract】 Post-earthquake investigation is the important way to gain seismic lessens and experience, meanwhile it is the base for aseismic theories and analytical methodologies. That is, engineering seismology cannot advance without earthquake investigations, typically vital destructive shocks. In the process of aseismic techniques evolvement in China, the deep post-earthquake investigations and in-situ field surveys and testing of previous earthquakes, e.g., Heyuan (1962), Xingtai (1966), Tonghai (1970), Haicheng (1975), Tangshan (1976) and Wenchuan (2008), have been greatly promoting engineering aseismic techniques and aseismic code formation in China.Earthquake liquefaction and relevant damage contributed considerable loss in seismic damage, and are kept close concern by geotechnical researchers and engineers. In the viewpoint of current achievements on liquefaction research, a big gap between the need for liquefaction mitigation and research exits typically in the fields of liquefied site characteristics and liquefaction-influencing factors based on real liquefaction field surveying materials and data, even though much progress has been realized. In recent years, the paucity of liquefaction research based on real liquefaction investigation data has restrained the advancement of geotechnical earthquake engineering and soil dynamics, which can be mainly summarized in the following. Macro liquefaction evaluation methods and investigation description standards in post-earthquake field survey cannot be found in literatures so that the overview of liquefaction scale and relevant loss in great earthquakes is hard to grasp. A systematic database of liquefaction documents and data is urgently needed for worldwide liquefaction documents and data archive. The field testing data analysis for site liquefaction in recent worldwide earthquakes has not been fully organized that the site characteristics revealed by real liquefaction data cannot be completely acquainted. The difference and coherence between Chinese liquefaction data and those of worldwide have not been identified, resulting in inappropriate understanding of the current status and future direction of liquefaction evaluation methods.Fairly abundant valuable liquefaction in-situ testing data from recent great earthquakes globally have been collected, which can be used to analyze the correlation of site characteristics and liquefaction. As a result, a novel acquaintance on the correlations of liquefaction responding to site property indexes, real dynamic loading intensity, soil conditions can be obtained so as to testify the current liquefaction evaluation methods.The main work and conclusions in this thesis can be drawn as fellow.1. Liquefaction data from48earthquakes globally have been collected to establish site liquefaction database. Soil layer conditions (i.e., sand buried depth, water tables), soil properties (i.e., relative density, particle diameter) and testing index (i.e., SPT) are analyzed so that the difference and common points in the site characteristics in China and other countries are comparatively portrayed. A complete and objective acquaintance of soil liquefaction is renewed to update the erratum and divergence in traditional liquefaction understanding.2. In terms of the need for post-earthquake investigation and current code updating, the concepts and corresponding classification of the macro-liquefaction index and macro-liquefaction grades are proposed in the thesis based on the thoughts and ideas conceived during liquefaction investigation in Wenchuan earthquake. The feasibility of the macro-liquefaction indexes and macro-liquefaction grades are testified by comparing the liquefaction data both in China and other countries. The macro-liquefaction indexes and grades can be adopted as the references for liquefaction investigation and evaluation, which provides necessary means for reliable liquefaction fundamental document collection and compilation.3. The liquefaction investigation materials and in-situ testing data in Wenchuan Ms8.0earthquake are systematically organized. Using the proposed macro-liquefaction indexes and grades, the liquefaction data and materials are analyzed to deep understand the liquefaction loss in the event. The macro-liquefaction indexes and macro-liquefaction grades in Chengdu, Deyang and Mianyang regions are depicted, while the seismic damage in liquefied and non-liquefied sites and the link of macro-liquefaction indexes with ground shaking are analyzed so that the liquefaction characteristics can be profoundly understood.4. In total,5103liquefaction data from51earthquakes worldwide are collected to explore the correlations of liquefaction with respect to PGA, ground water table, liquefied sand depth and site shear wave velocity by means of the Pearson product-moment correlation coefficient (PPCC) method. The correlations of liquefaction with the characteristic parameters under varying liquefied sand depth, ground water table and seismic intensity are comparatively analyzed. The correlations of liquefaction with respect to actual seismic loading and real sand buried conditions and in-situ site testing data are obtained and presented accordingly, including China mainland, Taiwan, Europe-USA and Japan. These can facilitate the understanding the relationships between liquefaction and soil layer parameters and ground shaking characteristics, and support to test the current liquefaction evaluation methods.5. The testifying of liquefaction discrimination formulae using SPT, CPT and Vs was performed by means of the liquefaction data-based correlation with respect to the site characteristics parameters using the collected liquefaction database. The reliability of the liquefaction discrimination formulae is evaluated that the erratum on the influence of soil layer buried depth on the CPT-based liquefaction discrimination formula is pinpointed. In the Vs-based liquefaction discrimination formula, the fact that the sand buried depth contributes too small in liquefaction evaluation is also revealed.6. Adopting the theories proposed in the thesis, the liquefaction data in Feb.22,2011, Christchurch New Zealand earthquake are selected to analyze the correlations of liquefaction with site characteristic indexes, i.e., sand buried depth, SPT counts, seismic shaking intensity. A complete and objective acquaintance of liquefaction in Christchurch earthquake is obtained while the liquefaction characters and relevant correlations are compared with those from other regions and countries.更多还原