埋地管道震害预测方法简述

埋地管道是城市生命线工程的重要组成部分,在地震时较易发生震害。影响埋地管道在地震中破坏特点的因素,主要是强烈的地面运动或场地失效以及管材、管径等因素。研究方法以基于经验统计的方法在实际应用中比较多。本文分别对基于理论计算和经验统计的震害预测方法进行了简述和比较,最后提出了基于综合概率的埋地管道分析预测模型。     

北京市区小区域地震影响

文中研究了北京及其周围地区的历史地震和地震地质资料,并在此基础上估计了基岩运动的参数。众所周知,局部地质、地形和土质条件等许多因素对给定场地的地面运动特性都是有影响的。本文着重考虑了土层的特性对地面运动的影响.作为分析工作的基础,我们研究了北京地区典型土层的动力特性。为了分析市区各场地上的地震反应,我们将它分成面积大体相等的许多网格,对于每一网格都分析了相应土层柱状在指定输入运动下的地震反应,通过电子计算和绘图装置将结果用许多图件表示,从而给出了不同场地上地震反应谱和强震地面运动的地区分布。这些图件可用来作为制定土地利用和防震规划的参考。我们根据市区每一地点的计算反应谱和典型结构的平均周期确定了相应结构的地震系数,结果已绘成等值线,这些图件可作为典型结构的震害预测和抗震设计的参考。      

利用强震记录进行场地反应分析研究综述

场地反应对地震动的影响是地震工程学中最重要的课题之一,一些破坏性大地震的震害资料表明局部场地反应可以大大加剧地面运动和建筑结构的破坏。分析比较了几种常用的利用强震记录来分析场地地震反应的方法,并就国内外研究现状做了总结。在此基础上详细介绍了各种方法的原理、适用性及存在的问题,针对其中的某些问题提出了可能的解决方法。对于场地地震动反应问题的进一步研究具有参考价值。     

高架交通工程场地效应震害防御探讨

通过分析由强烈地震引发的场地振动、地面破裂、地基失效和边坡破坏等震害效应令高架交通工程的墩桩基础产生位移、下沉、变形、折断,进而导致高架线路交通工程遭到破坏的实况．提出了一些基于工程场地地震安全性评价的高架线路场地地震地质灾害防御对策与工程地震勘测的建议。     

地下管道的震害预测方法简述

强烈的地面运动或场地失效等因素是造成地震中地下管道破坏的主要因素。本文对地震波作用下和砂土液化条件下管道的震害预测方法进行了概述,并基于综合概率法对埋地管道进行了分析预测。     

地震地面运动特性对结构地震需求的影响研究现状

在结构抗震设计和分析中,地震地面运动特性(用幅值、频谱特性和持时表示)的变异性对于结构地震需求的影响最大.震害经验表明,各类结构的震害均表现为这三个基本要素综合影响的结果.因此,从地震工程学和结构抗震两个方面,对国内外结构地震需求分析研究现状进行了较为全面的论述,包括分析方法、研究内容、影响因素等,重点论述了地面运动三要素对结构地震需求的影响,提出了存在的问题和今后尚需开展的研究工作.     

中国地震学会地震工程专业委员会成立大会暨地震小区划学术讨论会简讯

中国地震学会地震工程专业委员会成立大会暨地震小区划学术讨论会于三月二十三日至二十七日在南京召开。参加会议的有来自全国各地的建筑、水电、铁道、交通、化工、冶金、机械、地震、高等院校等科研、工程、和教学单位的地震工程科技工作者八十余人。会议交流了论文报告五十余篇。内容涉及到地震烈度区划,烈度异常、震害予测,场地与土质条件的影响,沙土液化以及地面运动分析与实验研究等方面。并结合我国多次大地震的震害     

三维竖向断层场地对地面运动的影响

实际工程场地中的断层通常具有三维尺寸,应进行三维分析。本文考虑均匀弹性半空间内存在不同长度、深度的三维断层,由下向上垂直入射一个脉冲波,主要采用三维时域显式有限元结合透射人工边界的方法及相应编写的三维显示有限元波动程序DSI3,计算断层附近地震地面运动的时程反应,研究含有三维断层场地地面运动的一些特点,并与自由场反应对比,以说明三维竖向断层对地震波传播的特点和对断层附近地面运动的影响。     

盐津5.1级地震现场调查与烈度分布

对盐津5．1级地震现场38个居民点、20所学校、8个卫生院（室）及计生站、21项生命线工程及水利工程结构、文化旅游设施和铁路等的震害调查资料进行了分析,得出了本次地震的等烈度分布及有关参数。分析了场地条件、断层、震害异常原因及各类房屋、生命线工程、水利设施等的震害特征和地质灾害特点,并提出了灾区恢复重建的减灾措施和建议。     

鹤壁市供电系统的震害预测

在对鹤壁地区的地震地质环境、地壳深部构造、新构造运动、地震活动性、地震危险性评估和场地条件等分析的基础上,利用“结构易损性分析”法对该供电系统的建构筑物,生命线工程和电业设施进行了震害预测,给出了在不同地震作用下的震害预测结果。     

北京的地震

1.緒言北京地区自古以来曾遭受多次剧烈地震的影响,迄今仍未趋于稳定。为了保障人民生命、財产和建設事業的安全,研究北京的地震現象,确定地震危險性的程度,以便采取适当的抗震措施,显然是当前刻不容緩的任务。远在1954年春,在中国科学院地震工作委員会的領导下,即开展了北京地震的研究。在工作过程中,經地球物理研究所和历史研究所第三所的密切配合并得到北京市     

北京的地震

1.緒言北京地区自古以来曾遭受多次剧烈地震的影响,迄今仍未趋于稳定。为了保障人民生命、財产和建設事業的安全,研究北京的地震現象,确定地震危險性的程度,以便采取适当的抗震措施,显然是当前刻不容緩的任务。远在1954年春,在中国科学院地震工作委員会的領导下,即开展了北京地震的研究。在工作过程中,經地球物理研究所和历史研究所第三所的密切配合并得到北京市     

计算结构竖向地震力的某些参数

地震对结构的破坏,传统观点认为水平地震力起着决定性作用,但我们分析很多种类型结构的大量震害后,却得出竖向地震力起主要作用的结论.我国多次地震的调查报告中都曾列举过直观上能看出竖向地震力起主要作用的很多震害.最近几年国内外的一些学者也发现了这一问题.有些国家的规范对竖向地震力作了大幅度的提高.因此,竖向地震力到底有多大的问题,已引起了地震工程学界的广泛注意.根据强震记录进行计算,技术问题已基本得到解决.但在强地震作用下结构真正的阻尼、力学性能,特别是地基的复杂影响都远远没有搞清,所以,计算结果可靠性有多大,还无法回答.本文分析了国内多次地震地面上多种物体的现象表明,它们的竖向加速度及结构的竖向地震力,远远高于传统观点.根据它来解释各种震害是令人满意的.所以,按反算办法,对计算竖向地震力的某些参数提出初步建议.     

大地震重复特征与平均重复间隔的取值问题

对延怀盆地及海原断裂古地震的详细研究表明,大地震的重复行为具有多样性。特征地震是大多数断裂活动的行为特征,但特征地震存在分级性,大地震的重复时间间隔存在分阶段性,以及断裂的相互作用会影响大地震的复发序列。因此,当大地震重复行为出现时间上的分阶段性,或特征地震分级现象导致不同强度的古地震间隔时间有明显差别时,用确定性或时间相依的概率方法评价大地震的危险性,需要分阶段或分级计算不同间隔阶段的平均值     

地面建筑倾倒方向与强震地面运动

本文通过对1976年唐山地震及其7.1级强余震宏观现象的分析,指出强震引起地面运动及建筑物的倒塌具有一定的优势方向。但同一地区不同强震引起的地面运动及建筑物的倒塌方向常不相同。发现强震高烈度区存在许多震害轻重相间的异常条带,其延伸方向大体上与地震断层平行。这种规律,给地震危险区内的各类工程、土木建筑的抗震设计提供了一些新的依据。     

Comparison of 1D non-linear simulations to strong-motion observations: A case study in a swampy site of French Antilles (Pointe-à-Pitre,Guadeloupe)

Observations from many recent strong motion events have shown the importance of local soil conditions and non-linear soil behaviour on the seismic ground response (site effects). As demonstrated by previous seismic microzoning studies (Lebrun et al.) [1]), as well as by at least three historical major earthquakes, Pointe-à-Pitre is prone to strong site effects, due to the particular geology of the area. In this paper, we present a comparison between the strong-motion data available from the stations operating on the swampy site of Pointe-à-Pitre airport and the ground motions derived from 1D non-linear finite element simulations.Results show that, for moderate to strong ground motions, 1D simulations reproduce the main characteristics of site response in terms of duration, energy distribution, amplitude and frequency content. It also shows the importance of very superficial soft layers as peat or saturated mud in low frequency site effects simulations. This point is important for further engineering studies since such very soft formations overlain by stiffer landfills are commonly expected in the Antilles context. Our work also shows that Anderson's criteria, used to quantify the goodness-of-fit of simulated ground motions to the observed ones, appear to be an interesting diagnostic tool for testing the quality of numerical simulations from an engineering point of view.     

Behavior of large fill dams during earthquake and earthquake damage

This paper describes the behavior of and damage to large fill dams during earthquakes. Although fill dams have been constructed since olden times, there are only records of recent earthquake damage. We analyzed the behavior of fill dams of at least 15 m in height during earthquakes, and investigated the damage to the fill dams. The fact that fill dams that are designed and constructed based on the modern design standards have never been failed but have been only slightly affected by past earthquakes in Japan and other nations suggests that such large fill dams are highly earthquake resistant. The modern conventional design methods (soil engineering control of the bank soil, method for evaluating slip safety, and evaluation method of the foundation ground) are thus fully adequate for determining earthquake resistance.     

Effects of multifocus earthquakes on seismic motion

Earthquakes may cause destruction disproportionate to ground conditions and distance from the epicenter. This paper suggests that disproportionate destruction may be caused by the long duration of the earthquakes. However, to date the mechanism leading to earthquakes of long duration was unknown. On the basis of a detailed analysis of a large number of macroseismic data from historical earthquakes in Armenia, we proposed during 1965–1992 that disproportionate destruction occurred as a result of the spatially separated multifocus character of these earthquakes. A new analysis of instrumental, geodynamic, and engineering-geological data on some typical highly destructive earthquakes that occurred in recent decades shows that the long duration of earthquakes is indeed related to their multifocus character. The destructive effect of the latter occurs irrespective of ground conditions and also at great distances from the epicenters. Seismic movements of long duration have additional impact on constructions, and on seismic instrumnents, as well. It is demonstrated which type of constructions are most vulnerable to long-duration earthquakes and which, on the contrary, are more resistant. We present some recommendations for improvement of the seismic construction code.     

Strong‐motion accelerographs: Early history

The structural design profession has long been interested in the design of structures to resist the strong horizontal shaking of the ground during potentially damaging earthquakes. Recordings of this ground motion have successfully provided the data on which building codes, design procedures and strong ground motion research are based. The object of this Historical Note is to chronicle the early development of strong ground motion accelerographs in the United States (the 1930s), Japan (the 1950s) and New Zealand (the 1960s)—accelerographs that recorded on photographic paper, waxed paper and film—and to describe the early processing of these analog records into digital form suitable for the emerging power of the digital computer. Ground accelerations and structural accelerations are now familiar concepts in seismic design and seismic engineering research, though many users may be unfamiliar with early efforts to identify them, record them and present them as useful data. Copyright © 2009 John Wiley & Sons, Ltd.     

Inferred ground motions on Guadeloupe during the 2004 Les Saintes earthquake

Accurate estimates of the ground motions that occurred during damaging earthquakes are a vital part of many aspects of earthquake engineering, such as the study of the size and cause of the uncertainties within earthquake risk assessments. This article compares a number of methods to estimate the ground shaking that occurred on Guadeloupe (French Antilles) during the 21st November 2004 (M _w 6.3) Les Saintes earthquake, with the aim of providing more accurate shaking estimates for the investigation of the sources of uncertainties within loss evaluations, based on damage data from this event. The various techniques make differing use of the available ground-motion recordings of this earthquake and by consequence the estimates obtained by the different approaches are associated with differing uncertainties. Ground motions on the French Antilles are affected by strong local site effects, which have been extensively investigated in previous studies. In this article, use is made of these studies in order to improve the shaking estimates. It is shown that the simple methods neglecting the spatial correlation of earthquake shaking lead to uncertainties similar to those predicted by empirical ground-motion models and that these are uniform across the whole of Guadeloupe. In contrast, methods (such as the ShakeMap approach) that take account of the spatial correlation in motions demonstrate that shaking within roughly 10 km of a recording station (covering a significant portion of the investigated area) can be defined with reasonable accuracy but that motions at more distant points are not well constrained.