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饱和砂土地震液化有可能诱发极为严重的破坏,已成为土动力学领域的重要研究课题之一。对液化的判别分为初判和复判。初判指根据已有的勘测资料或简单的测试手段,初步判别土层的液化可能。对于初判可能发生地震液化的土层,则再进行复判。鉴于土层液化的影响因素较多,我国规范建议采取经验方法,即标准贯入法,静力触探法,剪切波速法。单一判别方法都有局限性和适用范围,宜用各种方法综合判别。液化危害性评价使用危害性指标,分析液化对建筑物的危害程度。评价方法主要有液化指数法,震陷值法,谱强度比法和综合法。以评价指标为依据,划分液化影响的综合等级,全面反映液化危害程度。 相似文献
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砂土液化判别和评价综合方法研究 总被引:22,自引:1,他引:22
在汇总分析已有领域知识和笔者们研究成果的基础上,建立了一套比较系统的地震液化和评价综合方法,包括初判条件,液化判别、液化危害性分析和抗液化措施等内容。 相似文献
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土层液化对房屋遭受的地震荷载的影响 总被引:1,自引:1,他引:1
用液化后谱烈度比这一新指标来定量评价土层液化对房屋遭受的地震荷载的影响,同时研究了液化层厚度及其埋深、覆盖层刚度、液化层密度等因素所起的作用。计算结果表明,砖石房屋等短周期建筑往往受到隔震作用;长周期房屋遭受的地震荷载的变化比较复杂,有时加强震动,有时减小震动,取决于许多因素。 相似文献
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合理评价液化地基及采用科学的处理方案对工程建设有重要意义,总结了影响地基液化的主要因素及液化判定的一般方法,提出了一种新的液化判定方法——归一法。结合实例就液化地基的设计与处理谈了一些体会。 相似文献
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饱和砂土地震液化判别的分形插值模型 总被引:1,自引:0,他引:1
借鉴分形基本理论,提出了基于分形插值模型的饱和砂土地震液化判别方法.该方法首先选取影响饱和砂土地震液化判别的7个主要因素,根据分类标准,采用在每级标准中随机内插的方法,得到40个标准样本,用于构建饱和砂土地震液化判别的分形插值模型;其次根据最大似然分类原则确定每个饱和砂土地震液化判别指标的评价分维数;然后利用加权求和法计算样本的综合评价值,并根据样本综合评价值与经验等级之间的关系建立分形插值评价模型;最后,进行了实例分析结果表明:该模型的评价结果合理、客观,计算得到的每个样本具体得分值,即使对属于同一级的样本也可以给出其地震液化程度的顺序,为饱和砂土地震液化评价工作提供了一种新的研究方法与思路. 相似文献
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在过去的 1 0年中 ,印度发生了 5次大地震 ,最严重的是 2 0 0 1年 1月 2 6日普杰破坏性地震。这次地震特别提醒人们注意没有按抗御明显可能发生的大震来设计的建筑物所造成的危险性。这次地震还将公众的关注从印度一个预计会造成更严重破坏和生命损失的地区——喜马拉雅山脉弧形区 (图 1 ,略 )转移开来。一些证据表明 ,在喜马拉雅山脉大部分地区都有可能发生一次或多次大地震 ,威胁着这一地区的数百万人口。大量的地球物理证据表明 ,喜马拉雅山脉的南部作为印度基岩的顶表面 ,在喜马拉雅山脉下面折曲并滑动 (在大地震时是不稳定而倾斜的 )。… 相似文献
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目前对地下结构液化破坏的研究尚不完善,很有必要对地铁隧道等地下结构可液化土层的液化势进行分析。本文以太原地铁隧道液化破坏为研究对象,应用Tokimatsu和Yoshimi,Seed,Japan Road Associate和中国建规4种方法,分析其抗液化性,评价场地的整体液化风险;依据振动液化动剪应力比、抗液化安全系数、标贯击数与体应变的关系评价盾构隧道的液化沉降变形。在粉质砂土和黏质粉土盾构隧道仰拱基底二次灌浆抗液化的基础上,建议太原地铁可液化砂土地层采用水泥基悬液二次灌浆加固处理地基,以提高其抗液化能力,减小液化沉降变形。 相似文献
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For the seismic hazard evaluation of the region including the southern Calabro-Peloritanian Arc and southeastern Sicily, the determination of the macroseismic virtual intensity distributions has been carried out, characteristic of the seismogenic zones that fall within the area in study, starting with the structural framework of the region and from the analysis of the observed intensity effected through suitable filters. The macroseismic parameters, derived from such virtual distributions and used for seismic hazard evaluation, are not only a reference for eventual subsequently deeper knowledge referable to the need for a better characterization of the reference modelling, but distinguish themselves as an essential instrument for the definition of seismic hazard scenarios correlated to seismic events that take place in single seismogenic zones. 相似文献
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Bartolome C. Bautista 《中国地震研究》2002,16(3):236-242
It has taken more than a hundred years for seismic observations in the Philippines to evolve to a modern observation system.The responsibility of seismic observations was likewise transfeered from one agency to another during this same period of time.At present,the mandate of conducting seismic observatins in the Philippines rests with the Philippine Institute of Volcanology and Seismology(PHIVOLCS),In 2000,through a grant aid from the Japan International Cooperation Agency(JICA),the Philippine Seismic netowrk was upgraded to a digital system.As a result,a new set of seismic monitoring equipments was installed in all of the 34 PHIVOLCS seismic stations all over the country,Digital waveforms are now available for high level seismic data processing.and data acquisition and processing are now automated.Included in the upgrade is the provision of strong motion accelerographs in all stations whose data can now be used for studying ground motion and intensity attenuation relations,The new setup is now producing high-resolution data that can now be used for conducting basic seismological researches,Earthquake locations have now improved allowing for the modeling and delineation of earthquake source regions necessary for earthquake hazard studies.Current seismic hazard studies in the Philippines involve the estimation of ground motion using both probabilitstic and deterministic approaches,seismic microzonation studies of key cities using microtremor observations,paleoseismology and active faults mapping ,and identification of liquefaction-prone,landslide-prone nd tsunami-affected areas.The earthquake database is now being reviewed and completed with the addition of historical events and from data from regional databases,While studies of seismic hazards were primarily concentrated on a regional level ,PHIVOLCS is now focusing on doing these seismic hazard studies on a micriolevel.For Metro Manila,first generation hazard maps showing ground rupture,ground shaking and liquefaction hazards have recently been completed.Other large cities that are also at risk from large earthquakes are the next targets.The elements at risk such as population,lifelines,and vertical and horizontal structures for each of these urban centers are also being incorporated in the hazard maps for immediate use of planners,civil defense officials,policy-makers and engineers.The maps can also now be used to describe possible scenarios during times of strong events and how appropriate socio-economic and engineering responses could be designed.In addition,a rapid earthquake damage assessment system has been started which will attempt to produce immediate or rapid assessments identification of elements at risk durin times of strong earthquakes 相似文献
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In this article we present the modelling of uncertainty in strong-motion studies for engineering applications, particularly
for the assessment of earthquake hazard. We examine and quantify the sources of uncertainty in the basic variables involved
in ground motion estimation equations, including those associated with the seismological parameters, which we derive from
a considerable number of strong-motion records. Models derived from regression analysis result in ground motion equations
with uncertain parameters, which are directly related to the selected basic variables thus providing an uncertainty measure
for the derivative variable. These uncertainties are exemplified and quantified. An alternative approach is presented which
is based on theoretical modelling defining a functional relationship on a set of independent basic variables. Uncertainty
in the derivative variable is then readily obtained when the uncertainties of the basic variables have been defined. In order
to simplify the presentation, only the case of shallow strike-slip earthquakes is presented. We conclude that the uncertainty
is approximately the same as given by the residuals typical for regression modelling. This implies that uncertainty in ground
motion modelling cannot be reduced below certain limits, which is in accordance with findings reported in the literature.
Finally we discuss the implications of the presented methodology in hazard analyses, which is sensitive to the truncation
of the internal error term, commonly given as an integral part of ground motion estimation equations. The presented methodology
does not suffer from this shortcoming; it does not require truncation of the error term and yields realistic hazard estimates.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献