工程场地地震安全性评价工作中常见问题研究

本文对工程场地地震安全性评价工作中的常见问题进行了归纳和分析,着重指出了场址近场区断裂活动时代鉴定中控制性剖面缺失、测年数据应用不当、浅层人工地震探测方法的有效使用、钻孔探测的质量控制与孔间距、高密度电法的局限性等问题,强调应重视活动断裂活动性质、滑动速率、破裂分段和古地震事件等参数的获取;对场址范围活动断裂勘查和其他地震地质灾害评价中的若干问题也做了讨论;在发震构造判定和潜在震源划分中的一些不合理做法用实例做了论证。本文对提高今后工程场地地震安全性评价工作的水平提出了建议。     

罐罐岭断裂带最新活动特征

断层的最新活动时代以及分段特征一直在重大工程安全性评价中具有特别重要的意义。在解决黄河黑山峡地震地质问题时,通过对罐罐岭断裂带的航片解译、野外追踪调查、地形地貌测量和古地震槽探资料研究,从而确定了该断裂带的活动时代以及分段特征。该断裂带发育在青藏块体东北缘,是中卫-同心弧形活动构造带的一部分,总体走向近EW,长约60km,分为5条不连续的次级断层,各段成左阶羽列,晚第四纪以来表现出强烈的左旋走滑兼挤压逆冲活动特征。断层错断了一系列山脊、小冲沟和阶地等,发育醒目的断层陡坎。研究发现,罐罐岭断裂最新一次地震破裂发生在距今700～1200a之间,最大同震位移位于罐罐岭附近,全新世以来水平左旋最大错距达6m     

工程场地中活动断层和场地地震安全性评价

综述了工程场地地震安全性评价中活动断裂评价和场地评价的方法和步骤,指出了评价方法中存在的问题,并提出了解决方案。     

安徽西南宿松-枞阳断裂中段活动性的综合评价

安徽西南的宿松－枞阳断裂有历史记载以来曾发生多次中、小地震。综合近年来在该地区进行的一些重大工程场地地震安全性评价工作积累的资料，利用宏观、微观构造相结合的分析方法，配合断层物质测年等手段，对该断裂中段进行了较系统的研究，说明了近代中、小地震沿断裂发生的地质背景，并对断裂未来地震活动水平进行了初步预测，为弱震地区断裂活动习性综合评价提供了一个实例     

断裂微观滑移方式标志在地震安全性评价中的应用

将笔者近年来总结归纳出的活动断裂滑动特性民引入重大工程场地地震安全性评价工作中，结合样品的产出环境及宏观和超微观滑移特性标志分析，对样品所反映的最新活动方式进行鉴定，并在实践中补充和完善识别标志，从而为工程场地地震环境分析提供微观依据。     

地球化学在工程地震中的应用：瘦狗岭活动断裂探测

场地地震安全性评价中的近场区活动断裂评价是确定近场区地震活动水平的重要一环。实践证明,地球化学方法探测隐伏活动断裂效果很好。本文利用地球化学方法确定了瘦狗岭断裂东段的具体位置。     

地震危险性分析发展与工程应用

系统阐述了地震危险性分析方法发展中三种典型概率模型的特点和实质,它们被分别称之谓：简单概率模型、分段泊松模型以及复合概率模型。在此基础上,提出了一种基于复合概率模型的地震影响场等效地震的计算方法,并给出了它们在一个重大工程场地地震安全性评价中的应用。     

活断裂研究在二郎山公路隧道稳定性评价中的应用

国内外有关工程区及其区域的地壳稳定性的原则和方法，目前尚不一致。作者在二郎山公路隧道地壳稳定性评价工作中，借鉴前人的经验，结合自身的研究结果，提出了有关稳定性评价的七个参量。这七个参量值的获得，无不与工程区与区域的活动断裂有关，因而活动断裂的研究是地壳稳定性评价工作中最核心，最根本的问题。在二郎山公路隧道工程区周围，活动断裂主要有：康定－磨西断裂，大渡河断裂、龙门山断裂，保新厂－凰仪断裂和金坪断裂。在对这些活动断裂的研究工作中，采用地震地质、航卫片解译，热释光方法，ＳＥＭ、ＥＳＲ、大地形变测量、化探、地球物理场和地应力分析等诸多手段相结合的方法，以确定活断裂的最新活动时代、活动方式、活动速率及活动的分段性，并认为：大渡河断裂的主要活动时期为中更新世中，晚期，并可能在大约２０００年前有过一次快速运动事件，具粘滑运动方式，有发生６．０级地震的能力；康定－磨西断裂具分段性，北西段为全新世活动断裂，估计滑动速率为５－６ｍｍ／ａ，可能具备重复发生相似断错量地震的能力（７．０级或以上），南东段主要活动时期在晚更新世，其南东盘现代沉降率为０．５ｍｍ／ａ，北西盘现代抬升速率约为０．２８ｍｍ／ａ，具蠕滑运动方式；龙门山断裂的     

重大工程地震安评工作中的历史地震资料使用问题专题研讨会在合肥召开

历史地震资料的使用对重大工程地震安全性评价结果有相当大的影响，在地震构造活动较弱的中强地震活动地区这种影响尤为显著。近年来沿长江各省的核电选址工作，凸现了这一问题的重要性。为此，中国地震局震害防御司和中国地震学会历史地震专业委员会于2004年10月12—16日在安徽省合肥市召开了“重大工程地震安评工作中的历史地震资料使用问题专题研讨会”，安徽省地震局黄田庚局长、张鹏副局长、中国地震     

伊舒断裂的活动特征及其对拟建长春-辽源铁路的影响研究

本文较详细的论述了伊舒断裂带的基本特征、活动性、断裂分段及地震活动性,重点探讨了伊舒断裂带南段的活动性,从活动断层工程评价方面,研究了该断裂带对拟建长春-辽源铁路工程的影响。     

物理探测手段在地震安全性评价中的具体运用

结合3个工程实例,对地球物理探测手段在地震安全性评价中的应用进行分析和探讨,以便为今后地震安全性评价工作开展活断层探测提供参考。浅层人工地震法和高密度电法以其观测结果直观、高效、方便、经济等特点成为活断层物理探测手段首选。两种手段对于探测环境以及精度要求可以优势互补,在活断层探测结果的判断方面可以相互验证。     

薄覆盖层地区隐伏断层及其上断点探测的地震方法技术——以废黄河断层为例

通过在同一条测线上应用三种不同地震勘探手段(共偏移距地震反射法、横波反射法与高分辨率折射法)联合反演的方法,获得了测线控制地段内废黄河断层的确切位置、上断点埋深以及速度分布图像.探测结果表明:在薄覆盖层地区的断裂调查中,上述三种技术手段的联合反演要比单独使用其中任何一种手段更加可靠,并能从不同角度查明断层的位置、性质及其特征,为钻孔联合剖面位置的布设和钻孔深度的设计提供地震学依据.经高精度钻孔联合地质剖面证实,三种地震勘探方法反演得到的主要地层界面和构造特征都与钻孔联合地质剖面吻合较好.试验表明了上述三种地震勘探方法在基岩面埋深较浅地区联合反演的可行性以及地震勘探与钻孔联合地质剖面相结合的工作方法的有效性.     

The Principle and Method for Delineation of Potential Seismic Sources in Northwest Yunnan

INTRODUCTION Withrapideconomicdevelopment,deficiencyofelectricalpowerisbecomingincreasinglysevere.Therefore,theconstructionofmorehydropowerstationsinSouthwestChinawherehydropowerresources areabundantisinevitable.Presently,severalcascadepowerstationsarepla…     

Ongoing research on seismic safety assessment

Research on seismic safety assessment has been the centre of great interest among the scientific community in recent years. Although the devastating impact of earthquakes on current society should be incentive enough to increase research, the development of more realistic mechanical behaviour models and the continuous enhancement of computation capabilities are paramount factors contributing a great deal to the increase of such interest. In this context, three research areas can be identified as currently leading to important developments: code related research, especially in Europe where new design codes are in the implementation process; risk analysis, namely concerning the definition of methodologies for safety assessment that involve the evaluation of the failure probability and could be included in future generations of codes; and experimental characterization of constitutive laws which provides support for the development and calibration of accurate and realistic numerical models for seismic analysis and for the adequate characterization of limit state capacities. The paper will present some of the current scientific research trends on these three seismic safety assessment related topics. Studies addressing the seismic safety assessment of structures, either probabilistically or based on code provisions, and that consider realistic nonlinear mechanical behaviour models will be focussed. Reference will also be made to experimental research on the seismic behaviour of structural elements, emphasizing its crucial role to support the development of numerical models simulating the effects of different seismic strengthening techniques. Finally, given the development of studies leading to new trends and perspectives for performance based earthquake engineering, a possible scenario for seismic design in the future is presented, emphasizing the key issues for its implementation.     

大青山山前活动断裂带分段与潜在震源区划分

潜在震源区的划分主要包括潜在震源区范围的划定以及震级上限的确定,目前遵循地震构造类比和地震活动重复等原则。而活断层的分段特性也是潜在震源区划分时必须考虑的一个重要因素。大青山山前断裂带至今有3种不同的分段方案,文中比较分析了前人对大青山山前断裂带的分段,并在此基础上对大青山及山前盆地的潜在震源区作了新的划分。鄂尔多斯块体周缘被拉张性断陷盆地围绕,这些断裂系地震构造相似,且除呼包盆地外均有历史8级以上地震记录。文中将大青山山前断裂带与鄂尔多斯块体周缘断裂系进行了构造对比,特别是与华山山前断裂进行了断裂活动性定量对比,得出雪海沟到土左旗段的震级上限为8级,断裂两端潜源震级上限均为7.5级     

湖北西部恩施断裂活动性评价

通过分析恩施断裂的变形结构、运动学和动力学特征以及新活动和几何分形结构特征,结合断裂的活动时间测定,对湖北西部恩施断裂的活动特征进行了全面的研究,认为恩施断裂变形分段特征明显,活动具有多期次,且新构造期曾有活动,但现今活动极其微弱。同时,确定恩施断裂的活动时间上限为２０万ａ以上,重复活动的周期较长,对附近水电工程建设不会产生重大危害     

Seismic reliability assessment of classical columns subjected to near‐fault ground motions

A methodology for the performance‐based seismic risk assessment of classical columns is presented. Despite their apparent instability, classical columns are, in general, earthquake resistant, as proven from the fact that many classical monuments have survived many strong earthquakes over the centuries. Nevertheless, the quantitative assessment of their reliability and the understanding of their dynamic behavior are not easy, because of the fundamental nonlinear character and the sensitivity of their response. In this paper, a seismic risk assessment is performed for a multidrum column using Monte Carlo simulation with synthetic ground motions. The ground motions adopted contain a high‐ and low‐frequency component, combining the stochastic method, and a simple analytical pulse model to simulate the directivity pulse contained in near source ground motions. The deterministic model for the numerical analysis of the system is three‐dimensional and is based on the Discrete Element Method. Fragility curves are produced conditional on magnitude and distance from the fault and also on scalar intensity measures for two engineering demand parameters, one concerning the intensity of the response during the ground shaking and the other the residual deformation of the column. Three performance levels are assigned to each engineering demand parameter. Fragility analysis demonstrated some of the salient features of these spinal systems under near‐fault seismic excitations, as for example, their decreased vulnerability for very strong earthquakes of magnitude 7 or larger. The analysis provides useful results regarding the seismic reliability of classical monuments and decision making during restoration process. Copyright © 2013 John Wiley & Sons, Ltd.     

日本核电厂抗震设计及选址中的活断层评价

概要地介绍了日本核电厂抗震设计及选址中活断层评价的原则与方法、活断层调查程序和评价标准,以及活断层评价的经验与特点     

Estimation of the behavior factor of existing RC-MRF buildings

In recent years, several research groups have studied a new generation of analysis methods for seismic response assessment of existing buildings. Nevertheless, many important developments are still needed in order to define more reliable and effective assessment procedures. Moreover, regarding existing buildings, it should be highlighted that due to the low knowledge level, the linear elastic analysis is the only analysis method allowed. The same codes (such as NTC2008, EC8) consider the linear dynamic analysis with behavior factor as the reference method for the evaluation of seismic demand. This type of analysis is based on a linear-elastic structural model subject to a design spectrum, obtained by reducing the elastic spectrum through a behavior factor. The behavior factor (reduction factor or q factor in some codes) is used to reduce the elastic spectrum ordinate or the forces obtained from a linear analysis in order to take into account the non-linear structural capacities. The behavior factors should be defined based on several parameters that influence the seismic nonlinear capacity, such as mechanical materials characteristics, structural system, irregularity and design procedures. In practical applications, there is still an evident lack of detailed rules and accurate behavior factor values adequate for existing buildings. In this work, some investigations of the seismic capacity of the main existing RC-MRF building types have been carried out. In order to make a correct evaluation of the seismic force demand, actual behavior factor values coherent with force based seismic safety assessment procedure have been proposed and compared with the values reported in the Italian seismic code, NTC08.