建筑物地震易损性分析研究

本文系统地总结了近几十年来结构地震易损性分析及地震破坏损失预测的发展 ,指出了建筑物地震易损性分析存在的一些重要问题 ,如缺乏震害经验的建筑物地震易损性估计、采用地震动参数进行建筑物地震易损性估计等问题。本文重点研究了理论计算的易损性估计方法 ,给出了对于不同地震动建筑物出现或超越不同状态的概率 ,将多层砖房的理论易损性估计结果同实际震害资料进行了对比 ,并对经正规设计但缺乏震害经验的高层建筑地震易损性进行了估计。另外 ,本文也着重研究了以地震动峰值加速度及反应谱作为地震动输入参数时的结构地震易损性分析方法…     

芦山7.0级地震宏观场地效应

继汶川地震之后,2013年4月20日四川省庐山县又发生了7.0级强烈地震,其场地条件对震害的影响目前认识较少.通过专项工作,考察了雅安雨城区、芦山县、天全县、宝兴县等地区的结构震害及其场地条件,包括软土场地、老河床、不利地段、潜在滑坡等,分析了不同场地条件与震害的关系.结果表明,此次地震震害与场地条件有较密切关系,震害形式主要表现为软土震陷、河谷地形控制震害分布、不利地段加重震害、潜在滑坡的威胁、地质灾害堵塞交通等,其中软土震陷、河谷地形震害分布、不利地段处理都是值得深入研究的问题.     

水利水电工程震害分析及抗震措施建议

通过对汶川地震、通海地震、唐山地震和澜沧-耿马地震中水利工程破坏情况的统计分析,本文以统计表的形式直观地反映了水利工程震害的特点及破坏形式.根据水利工程的震害特点,探讨分析了水利工程震害的主要影响因素,结果表明地震烈度、结构设计、施工质量、地基及场地条件是水利工程震害的主要影响因素.基于水利工程震害的特点及主要影响因素...     

鲁甸5.6级地震震害分析

通过对云南鲁甸5．6级地震中47个居民点的震害调查,给出了本次地震的等烈度分布图,分析了场地条件与震害的关系、各类房屋的震害特征、典型房屋震害累积效应以及生命线工程震害。结果表明：这次地震比2003年11月鲁甸5．1、5．0级两次地震破坏严重,形成了Ⅷ度破坏区及较大范围的Ⅶ度和Ⅵ度破坏区,盆地区的震害比基岩区的要重．其主要原因是：①盆地区广泛分布有软弱地层;②震区建筑结构简易,抗震能力极差;③三次地震震区基本重叠,震害累积效应表现突出。     

四川会东1947年及云南禄劝1893年两次强震震害资料补遗

一、历史地震现场调查概况四川省会东县地处川滇交界附近的偏僻山区,1947年曾发生中强地震。1988年4月15日会东县鹿鹤乡发生5.2级地震,笔者随四川地震系统宏观考察组奔赴震区,除考察本次地震外,同时也注意搜集历史地震震害资料。由于历史地震发生的时间不太久远,当时的震害目击者多健在,许多震害情况为不同地点的群众所共同言及,增强了资料的可信度。为评定历史地震灾害程度,注意将同一地点的历史震害与本次地震震害进行对比,取得佐证。这次考察,对1947年6月7日会东地震及1893年禄劝地震增补了宏观震害资料,提出了校核会东地震震级参数     

汶川8.0级地震水坝震害调查

“5．12”汶川地震中水坝损毁严重,造成了巨大的经济损失。震后对69座溃坝险情和310座高危险情水库水坝进行了系统的调查,典型震害现象包括坝体裂缝、塌陷、滑坡、渗漏、启闭设施损坏和其他附属设施的损毁等。文中给出了不同烈度区的水坝震害分布,并对地震中水坝的震害现象做了初步总结和分析。     

2001年昆仑山口西8.1级地震区的冻土及地震破坏特征

通过对2001年昆仑山口西8．1级地震区冻土震害考察研究表明，震区主要存在冰碛、冲积、洪积和湖积等成因的冻土，沿地震破裂带冻土厚度变化较大。震区冻土变形破坏主要包括地震构造成因的地震破裂带和由地震振动引起的裂缝、液化、震陷和崩塌等。冻土中地震破裂带在地表主要以脆性变形为主，在地震断裂左旋走滑运动作用下，主要由剪切裂缝、张裂缝和开裂的挤压鼓包等组成。裂缝、液化、震陷和崩塌等变形破坏的展布特征及其组合形式与震区岩土与环境条件密切相关；本次地震震害具有地震破裂带规模大、有建筑物分布的青藏公路一线地震烈度衰减较快和震害分布受岩土条件影响大等特点。     

云南会泽5.3级地震灾害现场调查与烈度分布

通过对2005年8月5日云南会泽5．3级地震现场41个居民点的震害调查资料进行分析，得出了此次地震的等烈度分布图及有关参数，分析了场地条件、震害异常原因及各类房屋、生命线工程、水利设施、沼气池等的震害特征和地质灾害特点，并提出了帮助灾区恢复重建的建议。     

1999年11月29日岫岩—海城5.6级地震的烈度与震害

１９９９年１１月２９日在辽宁海城岫岩交界处发生了５．６级地震,这次地震造成的破坏、震中烈度达到了Ⅶ度,本文阐述了这次地震的宏观地震参数,烈度划分标度,烈度分布及震害特点等内容,与一般的５．５级左右地震相比,这次地震的特点是,震害偏重,震害分布不均匀,地震波的频谱效应从震害现象得到明显反映。     

大姚6.1级地震烈度与震害分析

综合2003年大姚6．1级地震震区85个居民点的震害调查资料,系统介绍了该地震的烈度分布及各烈度区的震害特征,并对大姚铜矿的震害现象做了专项分析,对震区烈度异常点的场地条件进行了分析。     

昆明盘龙江江岸对震害的影响

如果在昆明及其附近地区发生强烈的破坏性地震,当地震波传播到盘龙江江岸这一特定的场地条件时,对震害会产生怎样的影响?本文根据在强震考察中看到的一些河岸破坏的情况和对盘龙江江岸地区的一些工程水文地质资料及局部地区脉动观测结果分析指出:(1)强震时江岸地区易发生地裂,地陷和塌方等地基失效现象而加大震害。(2)由于江岸地区的土层含有饱和的砂土层,强震时易引起砂土液化导致地基失效而加大震害。(3)由于江岸地形的影响,强震时对振动起放大作用而加大震害。所以在昆明的城市规划建设中,盘龙江两岸在离岸边30米内最好不要建筑任何结构物,以免在强震时造成严重的破坏。     

雄安新区地震危险性评估

地震危险性评估对确定工程抗震设防等级、制定城市规划与减轻地震灾害等具有重要意义.由于传统分析方法存在诸多缺陷,用其对特定区域进行地震危险性评估可靠性差.本文基于孕震断层多锁固段脆性破裂理论,提出了利用岩石破裂自相似性预测研究区标志性预震的方法,并进而创立了一种以地震物理预测为基础的地震危险性评估新方法.雄安新区位于唐山地震区内,近邻运城地震区.基于唐山和运城地震区地震趋势分析结果及主要断裂展布与雄安新区位置关系,在唐山地震区内划分了保定研究区,在运城地震区内划分了行唐和十渡研究区.采用上述方法,预测了这三个区将发生的较大预震.根据某些学者提出的地震烈度经验公式,评估了唐山地震区发生标志性地震、预震及运城地震区发生预震导致的雄安新区地震烈度.结果表明,未来50年内,雄安新区抗震设防烈度从原7度调整为8度为宜.     

A PRELIMINARY STUDY ON THE CORRELATIVITY OF SEISMIC HAZARD BETWEEN BEIJING AREA AND XIONG'AN NEW AREA

Xiong'an New Area is established on April 1, 2017 and some non-capital functions from Beijing would be transferred to this new area. As a political, economic, and cultural center of China, Beijing has a highly dense population, buildings, and transportation. With the rapid development of the urban economy, the population and assets exposed to dangerous areas with M ≥ 7 earthquakes have accumulated in an exponential manner, leading to a continuous surge in seismic risk in Beijing. Studying on the correlativity of seismic hazard between Beijing area and Xiong'an New Area is of great significance to judge whether Xiong'an can play a role in the dispersal of seismic risk of Beijing. Using Monte Carlo method to simulate synthetic earthquake sequences, and for each simulated earthquake, the peak ground acceleration data sets on each site of Beijing and Xiong'an can be calculated through the attenuation relationship. Based on the statistical analysis of the ground motion peak acceleration data sets, this paper holds that the correlativity of the ground motion between Beijing area and Xiong'an New Area is not high; the probability of Beijing and Xiong'an suffering at the same time from an exceeded fortification level of ground motion effect is very low; the probability of Beijing and Xiong'an suffering at the same time from a rare ground motion effect is extremely low. Through defibering population, assets, and setting up a remote backup of earthquake emergency equipment and supplies, Xiong'an New Area can disperse the high seismic risk of Beijing to some extent.     

Seismic hazard analysis for engineering sites based on the stochastic finite-fault method

Seismic hazard analyses are mainly performed using either deterministic or probabilistic methods. However, there are still some defects in these statistical model-based approaches for regional seismic risk assessment affected by the near-field of large earthquakes. Therefore, we established a deterministic seismic hazard analysis method that can characterize the entire process of ground motion propagation based on stochastic finite-fault simulation, and we chose the site of the Xiluodu dam to demonstrate the method. This method can characterize earthquake source properties more realistically than other methods and consider factors such as the path and site attenuation of seismic waves. It also has high computational efficiency and is convenient for engineering applications. We first analyzed the complexity of seismogenic structures in the Xiluodu dam site area, and then an evaluation system for ground motion parameters that considers various uncertainties is constructed based on a stochastic finite-fault simulation. Finally, we assessed the seismic hazard of the dam site area comprehensively. The proposed method was able to take into account the complexity of the seismogenic structures affecting the dam site and provide multi-level parameter evaluation results corresponding to different risk levels. These results can be used to construct a dam safety assessment system of an earthquake in advance that provides technical support for rapidly and accurately assessing the post-earthquake damage state of a dam, thus determining the influence of an earthquake on dam safety and mitigating the risk of potential secondary disasters.     

昆明市区地震震害的不均匀分布特点及其重复性

本文以澜沧耿马地震时昆明震害调查资料为基础,结合地震史料,研究了昆明市区震害的不均匀分布,烈度有两度的差别。相对高烈度区与历史强震破坏的重震害点大部分重合。据此分析了震害重复特点及其与地质构造和沉积盖层的关系。本文可用于研究昆明市区及邻区强震对市区可能造成震害的大致分布,为震害预测、防震抗震和城市规划提供一些依据。     

Probabilistic seismic hazard model for Cairo,Egypt: estimates and uncertainties

A new seismic hazard model for Cairo, the capital city of Egypt is developed herein based on comprehensive consideration of uncertainties in various components of the probabilistic seismic hazard analysis. The proposed seismic hazard model is developed from an updated catalogue of historical and instrumental seismicity, geodetic strain rates derived from GPS-based velocity-field of the crust, and the geologic slip rates of active faults. The seismic source model consists of area sources and active faults characterised to forecast the seismic productivity in the region. Ground motion prediction models are selected to describe the expected ground motion at the sites of interest. The model accounts for inherent epistemic uncertainties of statistical earthquake recurrence; maximum magnitude; ground motion prediction models, and their propagation toward the obtained results. The proposed model is applied to a site-specific hazard analysis for Kottamiya, Rehab City and Zahraa-Madinat-Nasr (hereinafter referred to as Zahraa) to the East of Cairo (Egypt). The site-specific analysis accounts for the site response, through the parameterization of the sites in terms of average 30-m shear-wave velocity (Vs30). The present seismic hazard model can be considered as a reference model for earthquake risk mitigation and proper resilience planning.     

The earthquake of October 9, 1864 in western Transbaikalia

The area of western Transbaikalia is characterized by moderate seismic activity. Nevertheless, there is historical and instrumental evidence to show that rather strong seismic events have occurred in the area and caused considerable material damage to the population centers around their epicenters. Seismological knowledge of the region is scant. The earthquake catalogs for the area and for the historical period of time need to be corrected and supplemented. The present paper considers the earthquake of October 9, 1864, which has not been included in any parametric catalog thus far. New primary data that were found in the regional periodic press were used to determine the epicenter and magnitude (M = 5.1) for the event. The earthquake of October 9, 1864 is a “forgotten” event, but is a significant addition to the catalog for western Transbaikalia. The materials presented here can be used to assess earthquake hazard for the area, as well as to aid in the search for other unknown or “forgotten” earthquakes.     

辽宁省地震易发区地震危险性研究

盘锦、海城、营口地区是辽宁省内地震活动性最强、地震危险性最高的地区。该地区开展了大量重点工程地震安全性评价、区域性地震区划和地震小区划工作，但尚未开展基于场地条件的区域尺度地震危险性研究。独有的沉积特点使该地区场地条件较复杂，因此在地震危险性概率分析中考虑场地条件是必要的。本文基于新一代中国地震动参数区划图基本原理和技术原则，结合盘锦、海城、营口地区场地条件特征，采用基于地形坡度的方法对场地条件进行分类，确定场地地震动影响系数，给出该地区基于区域场地条件的地震危险性分布，相关研究结果可为地震风险评估和防震减灾规划提供参考。     

Multi scenario seismic hazard assessment for Egypt

Egypt is located in the northeastern corner of Africa within a sensitive seismotectonic location. Earthquakes are concentrated along the active tectonic boundaries of African, Eurasian, and Arabian plates. The study area is characterized by northward increasing sediment thickness leading to more damage to structures in the north due to multiple reflections of seismic waves. Unfortunately, man-made constructions in Egypt were not designed to resist earthquake ground motions. So, it is important to evaluate the seismic hazard to reduce social and economic losses and preserve lives. The probabilistic seismic hazard assessment is used to evaluate the hazard using alternative seismotectonic models within a logic tree framework. Alternate seismotectonic models, magnitude-frequency relations, and various indigenous attenuation relationships were amended within a logic tree formulation to compute and develop the regional exposure on a set of hazard maps. Hazard contour maps are constructed for peak ground acceleration as well as 0.1-, 0.2-, 0.5-, 1-, and 2-s spectral periods for 100 and 475 years return periods for ground motion on rock. The results illustrate that Egypt is characterized by very low to high seismic activity grading from the west to the eastern part of the country. The uniform hazard spectra are estimated at some important cities distributed allover Egypt. The deaggregation of seismic hazard is estimated at some cities to identify the scenario events that contribute to a selected seismic hazard level. The results of this study can be used in seismic microzonation, risk mitigation, and earthquake engineering purposes.     

Rapid report of June 1, 2022 MW 5.9 Lushan earthquake,China with geodetic and teleseismic data

Timely response to earthquake characterization can facilitate earthquake emergency rescue and further scientific investigations. On June 1, 2022, M_W 5.9 earthquake occurred in the southern area of the Longmenshan fault zone. This event also happened at the south end of the Dayi seismic gap and is the largest earthquake that has occurred in this seismic gap since the 1970 M 6.2 event. The slip-distribution model constrained by the seismic waveforms suggests a thrust-dominated faulting mechanism. The main slip occurs at a depth of ～14 ?km, and the cumulative energy is released in the first 6 ?s. The variations of Coulomb stress caused by the mainshock show a positive change in the southwest area of the Dayi seismic gap, indicating possible activation of future earthquakes. In addition, we emphasize the importance of rapid estimation of deformation for near-field hazard delineation, especially when interferometric radar fails to image coseismic deformation in a high relief terrain.