论工程场地地震安全性评价中历史地震影响烈度的分析方法：以南澳跨海大桥？

合理地确定场地的历史地震影响烈度，是工程场地震安全性评价工作中的重要一环。本文以广东南澳跨海大桥场址为例。论述了历史地震影响烈度分析的要点。首先对南澳附近１９１８年７．３级地震的震中位置及对桥址的影响烈度进行了确认。     

工程场地影响烈度调查

本文以1918年南澳7．3级地震对粤东核电乌屿厂址影响烈度调查为例,探讨了重大工程场地影响烈度调查方法。其调查结果不仅为该厂址评定历史地震最大影响烈度提供了依据,也为修定1918年南澳7．3级地震的等震线准备了条件。本文所采用的方法,将有助于类似的工程场地开展影响烈度调查。     

城市地震影响特征研究

首先根据历史地震目录，计算了我国34个省会城市所受到的历史地震影响. 这些城市的地震影响烈度分布特征表明，约53%的省会城市没有遭受过Ⅵ度以上的历史地震影响，遭受过Ⅶ~Ⅸ度影响的城市有44%；大部分城市Ⅵ度地震影响的发生频次均高于Ⅵ度以上地震影响；不同城市最大发生频次的地震影响烈度也不同. 为此，在确定城市地震防御烈度时，需综合考虑最大影响烈度和最频影响烈度. 本文还考虑到历史地震记录的不完备性，以福建省69个县级以上城市为研究对象，采用模拟地震目录的方法来研究城市地震影响的特征. 结果表明，不同超越概率水平下城市地震影响烈度在不同城市之间表现出较大变化，以50年超越概率2%作为城市特征地震影响烈度，可以作为城市地震防御烈度确定的依据，并据此对城市未来地震影响进行合理的描述.      

场地影响烈度的频次特征及其工程地震的意义

本文通过对河北省廊坊、万庄、桐柏、迁安、新庄、乐亭、王滩,江苏省江阴等八个工程场地影响烈度的频次分布情况进行分析,发现工程场地的影响烈度与相应频次之间存在对数直线关系。根据这种对数直线关系可以得到工程场地各烈度的年平均发生率,进而可以对场地在未来50年、100年可能遭遇到的烈度进行预测。其预测结果与烈度复核和地震危险性分析的结果是十分相近的。因此,只要工程场地所在地区有足够多的历史地震资料,就可以利用场地影响烈度的频次分布特征来评价工程场地的地震危险性。     

以山西中部地区为例利用历史地震影响烈度进行地震区划的研究.

以山西中部地区为例，直接利用历史地震影响烈度进行地震区划的研究．结果表明:① 在历史地震资料比较丰富的地区，可以利用场地影响烈度的统计特性来编制具有概率含义的地震烈度区划图；② 在确定统计时段时，应充分考虑影响烈度资料的完整性和区域地震活动的非均匀性；③ 将平均重现期为500 a的烈度区划结果与新的中国地震烈度区划图(1990)相比较，两者在分区形态上大体相近，个别地段有差异，也各有其合理性．      

引入地震构造法的场地影响烈度地震危险性分析 --以皖西六大水库坝址为例

地震构造法是通过研究工程场地周围每一发震构造及最大潜在地震来确定场地未来的极限地震危险性。引入地震构造法，结合区域地展地质资料进行场地影响烈度地震危险性分析，将会取得更为科学可靠的结果。本文以皖西六大水库坝址为例，考虑地震构造条件，进行场地影响烈度地震危险性分析，给出50年P(I≥i)＝10％的分析结果。研究结果表明，发震构造及最大潜在地震对周围场地未来地震危险性具有明显的控制作用。     

用不确定的宏观地震数据估算场地地震重复率

提出了一个根据有不确定影响的烈度资料来决定场地地震危险分析的方法。这种方法考虑了烈度的顺序和互不关联的特征，试图避免由于假定强度可以被处理作一个实数（连续分布估计量、衰减关系式等）而导出的错误结果。所提出的公式基于采用一个分布函数，它对每一个地震描述了场地受每一个烈度值影响的可以性。为了得到缺少当地地震资料地区的场地危险的评价，检验了这个分布函数随着到宏观地震震中的距离和震中烈度的变化情况。为了结     

论历史地震研究在工程地震中的作用

本文通过回顾，展望及对现行《工程场地地震安全性评价工作规范》有关条文的理解，论述了历史地震研究在工程地震中的重要作用。历史地震研究，不仅在甄别历史地震参数、评定场地的地震基本烈度、编制地震烈度区划图、分析地震资料的时空不均匀性和历史地震对场地的方面是主要的手段和方法，而且在提供具有概率含义的抗震设防参数、编制综合性的设防区划图、确定背景地震强度等方面，也可能成为重要的方法。     

基于地震场地烈度频度的地震期望损失估计方法

在目前流行的地震期望损失方法中，往往忽视了在给定年限内，可能遭受多次同一烈度的影响，在具体计算某地震烈度的发生概率时，常用场地极值影响烈度来代替。这样处理，往往会低估地震的损失，特别是给定年限较长的情况下更是如此。笔者根据地震影响烈度造成损失的实际情况，建立了期望损失的新的框架：给定时间段内，某地震影响烈度的期望损失，等于给期望烈度的期望次数与给烈度下每次地震造成的平均损失之积；总的期望损失等于各场地影响烈度事件造成损失的总和。依据新的全国烈度区划图采用的地震活动性模型，笔者推导了地震期望损失估计和损失估计方差的计算公式。通过计算实例和与目前流行方法的比较表明，采用本文提出的方法不但是可行的，而且是必要的。本文给出的方法，将使地震灾害预测、地震保险和防灾预测建立在更为科学的基础上。     

用地震烈度史料预测场地地震危险性及与地震危险性分析的初步比较

本文介绍一种新的评估场地地震危险性的概率方法。该方法主要依据场地历史地震影响烈度资料,其特点是吸收了地震危险性分析的某些思想,并能引进区域未来地震活动趋势估计。文中提出有关参数综合确定方法并对一些问题进行了讨论。作为实例,预测了14个工程场地地震危险性。与地震危险性分析方法相比,该方法具有计算简便,不确定性和敏感性因素较少的优点,并能用实际资料检验所求的场地总危险性P(I≥i)。在地震和烈度史料丰富的地区,本方法可以取得比目前危险性分析更稳定的结果。     

Study on the characteristics of earthquake''''s impact on cities

Introduction With rapid development of national economy, urbanization has been speeded up in China, and several city groups or city belts with extra-large cities as their centers have been formed. For example, Pearl River Delta urbanized area surrounds Guangzhou City, Shenzhen City, Zhuhai City; Yangtze River Delta urbanized area surrounds Shanghai City, Suzhou City, Wuxi City, Nanjing City, Hangzhou City; Beijing-Tianjin-Tangshan urbanized area surrounds Beijing City, Tianjin City…     

中国历史地震烈度表研究

在比较分析以往烈度表的基础上,着重增加了社会反响标志;对Ⅹ-Ⅻ度的房屋建筑物和地表现象标志进行了调整与补充,完善了作为12阶烈度表相应的《中国历史地震烈度表》.文中对烈度表的各项标志作了简要说明,并列举了国内外10次历史地震事件的评定实例.本文提出的历史地震烈度表,保持了以往烈度表的适用性与一致性.     

华北地区烈度衰减模型建立及其用于震中区域和震级的定量估算.

利用地震烈度资料定量估算历史地震震中区域和震级的方法是由Bakun和Wentworth于1997年首先提出的．该方法定量程度高,对烈度数据较少或发生在近海的历史地震的定位和震级估算尤为有效．按照Baku和Wentworth给出的思路,笔者尝试了对我国华北地区的历史和近代地震的震中和震级进行初步分析．首先,选取20世纪以来发生在该地区的10次有仪器记录的地震（5.3le;MSle;7.8）,对该地区的烈度-震级-震中距衰减关系进行标定并给出了烈度衰减模型,表明华北地区烈度随震中距增大而衰减的速率明显小于美国加州地区（约50%）．在此衰减模型的基础上,提出了确定震级和震中区域的网格搜索试算方法（GSTSL）,并给出了适用于华北地区的圈定震中区域和烈度震级的等值线置信值．最后,讨论了计算震中区域等值线时所引进的权因子Wi及其中参数b对震中区域等值线圈闭性的影响．利用该方法,对发生在1668年莒县——郯城地震,1679年三河——平谷地震,以及1966年隆尧地震和1969年渤海地震进行了分析．需要指出的是,该方法也可推广应用于我国其它历史地震资料丰富的地区．      

闽粤海外历史地震与台湾海峡现今强震活动图像

闽粤两省强烈地震多发生在沿海地区,且福建南日岛至广东南澳一线的泉州－汕头地震带地震活动尤为突出。历史上东南沿海地震带曾发生过４次７级以上大地震,而其中３次都发生在泉－汕段海域,继华南地区本世纪著名的１９１８年广东南澳７．３级地震后,１９９４年９月１６日台湾海峡南部又发生７．３级强震,这在经济发达,人口稠密的闽粤沿海地区引起了极大关注。本文通过历史强震活动资料,分析闽粤沿海与台湾海峡强震在时间进程,     

Study on the characteristics of earthquake’s impact on cities

Firstly, the impact of historical earthquakes on 34 China province-level capital cities is evaluated by using historical earthquake catalog. The distribution of affected intensity shows, about 53% of cities have even not been affected by earthquake intensity VI, and 44% of cities have been hit by earthquake intensity VII to IX. For most of the cities, occurrence frequency of affected intensity VI is usually higher than that of affected intensity larger than VI, and the value of affected intensity with maximal occurrence frequency may be very different among cities. So both the maximal affected intensity and the affected intensity with maximal occurrence frequency should be taken into account when the prevention seismic intensity needs to be determined. Secondly, considering the incompleteness of records of historical earthquakes, a method of earthquake catalog computer simulation is introduced to study the features of affected intensity of big cities. 69 county-level cities of Fujian Province are selected to be statistical objects. The statistical result shows, for different risk levels the seismic intensity changes greatly among cities, the seismic intensity of 2% probability of exceedance in 50 years can be regarded as the characteristic affected intensity of city, and can be the basis of determining the city special earthquake prevention level and a proper indicator of future earthquake’s impact on cities. Foundation item: A Public Benefit Foundation of the Ministry of Science and Technology of China. Contribution No. 04FE1005, Institute of Geophysics, China Earthquake Administration.     

利用地震烈度数据重构历史地震震级和震中位置的方法

采用现代仪器地震记录和烈度资料,我们建立了用于定量估算历史地震震级和震中位置的烈度衰减模型和分析方法,并对我国西南川滇地区的历史和近代地震的震中和震级进行了重新分析.利用20世纪以来该地区十四个有仪器记录的地震（5.9≤M_s≤8.0）及相应的烈度数据,对其烈度-震级-震中距衰减关系进行标定,并建立了用于震中和震级估算的烈度衰减模型.结果表明,当震级一定时,川滇地区烈度随震中距增大而衰减的速率明显小于美国加州地区（～60%）.在衰减模型基础之上,发展了确定震中区域和震级的网格搜索试算方法（GSTSL）,并给出了确定震中位置和震级的等值线置信值.采用所建立的分析方法,对1786年康定地震,1850年西昌地震,1913年峨山地震和1970年通海地震进行了分析,给出了更为精确合理的结果.     

Seismic interaction at separation joints of an instrumented concrete bridge

A multi-span, curved, concrete box-girder bridge has been extensively instrumented by the California Strong Motion Instrumentation Program (CSMIP) in cooperation with the California Department of Transportation (Caltrans). On 28 June 1992, the bridge was shaken by the magnitude 7–5 Landers and magnitude 6–6 Big Bear earthquakes in southern California. The epicentres of these earthquakes were 50 and 29 miles (81 and 46 km) from the bridge, respectively. All 34 strong-motion sensors installed on the bridge recorded the response to these earthquakes and provided an insightful set of data. A striking aspect of the response is the presence of intermittent sharp spikes in nearly all of the acceleration records from sensors at the deck of the bridge. Among these the highest spike was 0.8g for the Landers and 1.0g for the Big Bear earthquake. The peak ground acceleration at the bridge site was only about 0.1g for both these earthquakes. With the aid of visual examination and simple analysis it is deduced that (1) the spikes were caused by forces generated at separation joints by impacts and stretching of the cable restrainers between adjacent bridge segments; (2) the forces of impacts and cable stretching are directly proportional to the size of the spikes and can be estimated by the use of a simple formula; and (3) the spikes travelled from their source to other locations on the bridge with the velocity of a compression wave propagating through concrete.     

A Magnitude-Felt Area Relation in the Evaluation of the Magnitude of Historical Earthquakes

An evaluation of the magnitude of historical earthquakes is proposed, through an empirical relation based on a felt area of historical earthquakes derived from a vectorial modelling of macroseismic intensity distribution.     

SEISMIC INTENSITY EVALUATION MODEL IN MEIZOSEISMAL AREA BASED ON FOCAL DEPTH

China is the country with the challenge of severe earthquake disaster. In order to mitigate the disaster and save lives, emergency response and rescue work after an earthquake are deployed and led by the Chinese governments at all level, the effectiveness of which has been proved. In such work, how to quickly evaluate the seismic intensity in meizoseismal area is a crucial issue at the early period after the earthquake. It is the foundation to estimate the disaster losses and decide the scale of rescue teams and materials. However, at the early period only a few physical parameters of the earthquake can be acquired and some of them may even be inaccurate. An evaluation model of seismic intensity in meizoseismal area is investigated and presented by statistic method in this study. After an earthquake there are four authoritative parameters officially released by China Earthquake Administration generally within ten minutes:earthquake magnitude (M_S), focal depth, latitude and longitude position, and the occurrence time. They are good candidate input parameters of the evaluation model. We collect the information of 215 historical earthquake occurring in China from 1966 to 2013, including:The four parameters and the seismic intensity in meizoseismal area. Through statistical analysis we find the seismic intensity in meizoseismal area has high correlation with the earthquake magnitude (M_S) and the focal depth and then select them as the formal input parameters. After further investigation a generalized linear model is built to fit the relationship between the seismic intensity in meizoseismal area, earthquake magnitude (M_S) and the focal depth. The effectiveness of the model is validated by the Sig value and F value from theoretic perspective. The validation also includes the application of the model in real earthquakes occurring from 2014 to 2017. After the earthquakes, the seismic intensities in meizoseismal area have been quickly estimated and used in the command of national earthquake disaster emergency relief. The applications in real earthquakes get good results. Finally, the robustness of the model is analyzed. We respectively verify the influences of the earthquake magnitude (M_S) and the focal depth and find the seismic intensity in meizoseismal area is more sensitive to the earthquake magnitude. Under the condition of the same focal depth, when the change of the earthquake magnitude is up to 0.5, the change of the seismic intensity will reach to 1. However, in order to cause same change of the seismic intensity, the difference of the focal depth will be 10 kilometers. Basically, these changes derived from the model meet the situation of historical earthquakes.