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1.
We calculated theoretical acceleration response spectra at the ground surface in the region near the 1995 Hyogo-ken Nambu earthquake source based on the spectral moment method. To estimate earthquake motion on the ground surface, a formula of earthquake motion at base rock level was derived. The amplification effect of the ground was introduced by using multiple reflection theory. Theoretically estimated response spectrum were modified by the response spectra calculated using observed earthquake motions. 相似文献
2.
本文根据广东沙环核电厂厂址地震地质环境特点和有关核法规的技术要求完成了设计地面运动时程的人工合成。从持续时间、合成精度、包络设计谱、功率谱密度函数、多根合成时程的统计不相关等方面讨论了该人工合成设计时程对ＡＳＣＥ４－８６ＳｔａｎｄａｒｄａｎｄＣｏｍ－ｍｅｎｔａｒｙｏｎＳｔａｎｄａｒｄ和Ｕ．Ｓ．ＮＲＣＳａｔｎｄａｒｄＲｅｖｉｅｗＰｌａｎ两个基本法规技术要求的可接受性。 相似文献
3.
本文根据广东沙环核电厂厂址地震地质环境特点和有关核法规的技术要求完成了设计地面运动时程的人工合成。从持续时间、合成精度、包络设计谱、功率谱密度函数、多根合成时程的统计不相关等方面讨论了该人工合成设计时程对ASCE4-86StandardandCom-mentaryonStandard和U.S.NRCSatndardReviewPlan两个基本法规技术要求的可接受性。 相似文献
4.
Nonlinear Analysis of Local Site Effects on Seismic Ground Response in the Bam Earthquake 总被引：1，自引：0，他引：1
M. H. T. Rayhani M. H. El Naggar S. H. Tabatabaei 《Geotechnical and Geological Engineering》2008,26(1):91-100
The influence of local geologic and soil conditions on the intensity of ground shaking is addressed in this study. The amplification
of the ground motion due to local site effects resulted in severe damage to dwellings in the Bam area during the 2003 Bam
Earthquake. A unique set of strong motion acceleration recordings was obtained at the Bam accelerograph station. Although
the highest peak ground acceleration recorded was the vertical component (nearly 1 g), the longitudinal component (fault-parallel
motion) clearly had the largest maximum velocity as well as maximum ground displacement. Subsurface geotechnical and geophysical
(down-hole) data in two different sites have been obtained and used to estimate the local site condition on earthquake ground
motion in the area. The ground response analyses have been conducted considering the nonlinear behavior of the soil deposits
using both equivalent linear and nonlinear approaches. The fully nonlinear method embodied in FLAC was used to evaluate the
nonlinear soil properties on earthquake wave propagation through the soil layer, and compare with the response from the equivalent
linear approach. It is shown that thick alluvium deposits amplified the ground motion and resulted in significant damage in
residential buildings in the earthquake stricken region. The comparison of results indicated similar response spectra of the
motions for both equivalent and nonlinear analyses, showing peaks in the period range of 0.3–1.5 s. However, the amplification
levels of nonlinear analysis were less than the equivalent linear method especially in long periods. The observed response
spectra are shown to be above the NEHRP building code design requirements, especially at high frequencies. 相似文献
5.
A deterministic seismic hazard analysis was conducted to address the effect of local soil conditions on earthquake-induced strong ground motion in the Las Vegas Basin, Nevada (US). Using a large geological and geotechnical database, two response units were defined: a fine-grained unit, predominantly clay; and a coarse-grained unit, predominantly gravel. A moderate number of high-quality shallow shear wave velocity measurements were collected from which characteristic shear wave velocity profiles were developed for each response unit. An equivalent-linear one-dimensional site response model was used. The model was calibrated using a basin-wide, small-strain ground motion database. Calibration tests showed that ground motion projections become increasingly conservative with increasing ground-motion amplitude. Projections were overconservative for the coarse-grained response unit, likely due to the sparseness of the velocity database. For the earthquake response analyses, historical ground motions were used to model characteristic ‘bedrock’ motion for earthquakes on 10 faults judged to be critical. Response spectral envelopes were generated for each unit through Monte-Carlo simulations. For the fine-grained response unit, 95th percentile peak ground acceleration, peak spectral acceleration and predominant period were 310 cm/s2, 1100 cm/s2, and 0.29 s, respectively. With respect to codified design spectra, projections are lower at short periods and higher at long periods. Projections of peak spectral accelerations for the coarse-grained response unit, were more than double that of codified spectra; however, they are believed to be overconservative. Near-fault effects and basin-edge effects, though potentially important, were not considered in these analyses. 相似文献
6.
沙牌坝址基岩场地地震动输入参数研究 总被引：2，自引：0，他引：2
重大水利水电工程地震动输入参数必须根据专门的地震危险性分析结果来确定。目前由地震危险性分析得到的一致概率反应谱具有包络的意义,不能反映实际地震的频谱特性,输入“一致概率反应谱”可能导致地震作用偏大;拟合设计反应谱人工生成地震动加速度时程的频率非平稳性也没有得到很好解决。为了解决这些问题,得到与坝址地震危险性一致、具体地震的输入参数,结合沙牌大坝提出了一套适用于重大水利水电工程基岩场地地震动输入参数确定方法：通过以有效峰值加速度为参数的概率地震危险性计算分析,确定坝址不同超越概率下的有效峰值加速度及对坝址贡献最大的潜在震源区;在最大贡献潜在震源内利用震级空间联合分布概率最大法确定坝址设定地震,依据加速度反应谱衰减关系确定与坝址设定地震对应的设计反应谱;根据设定地震结果和时变功率谱模型参数衰减关系确定时变功率谱,将时变功率谱和最小相位谱按三角级数叠加法进行强度和频率非平稳地震加速度时程合成。在对沙牌坝址区域的地震活动性及地震构造环境分析评价的基础上,采用上述方法,得到了坝址基岩场地不同超越概率下的有效峰值加速度、设计反应谱、强度和频率非平稳地震加速度时程等地震动输入参数。 相似文献
7.
Tatyana Novikova Gerassimos A. Papadopoulos Vassilios Karastathis 《Natural Hazards》2007,40(3):537-552
In the present paper we analyze the effect of local geology on ground motion by means of numerical calculations (numerical
models) using total (TS) and effective stress (ES) methods. These numerical calculations have been applied to the site of
Itea, Corinth Gulf, which was chosen based on liquefaction susceptibility criteria and field inspection. Data from seismic
refraction experiments and cone penetration test N-values as well as selected records of ground motion in nearby areas were
used to construct the input file for the numerical model. By means of␣dynamic analysis such characteristics of ground motion
as acceleration time histories, response spectra, and amplification function were evaluated. A one-dimensional soil amplification
effect was clearly shown. Liquefaction probability at the Itea site was predicted based on the safety factor and the calculation
of the induced settlement at the test site. Results of the TS and ES modeling lead us to conclude: (1) the presence of soft
soil at Itea caused significant amplification (almost 2.5-fold higher magnitude) of the underlying bedrock motion and, therefore,
can contribute to damage; (2) the area of Itea is highly susceptible to liquefaction due to presence of silty sand deposits
at depths between 2.48 m (the position of the water table) and 12 m that demonstrate the rapid growth of the excess pore water
pressure (EPWP) ratio with an increase in peak ground acceleration values. 相似文献
8.
9.
香港地区地震风险评价和设防区划 总被引：3，自引：0，他引：3
香港地区隶属于中国板内地震区中的东南沿海块缘地震带。港-九块体为晚中生代至早第三纪以来以持续稳定上升为主的块体, 块体活动性明显地低于其周边相对下沉的中新生代盆地。为此, 赋予港-九块体为最大可信震级M=5.5级潜在震源区, 而其周边中新生代断陷盆地则为最大可信震级M6.0潜在震源。从大陆地震构造成因的环境、潜在震源可信震级范围M=5.0～7.5和近源地震动饱和等三个方面的可比性, 结合中国大陆地震震源破裂尺度和地震烈度影响场, 所建立的反映中国地震构造和震源破裂及地震烈度影响场特点的PGA和反应谱地震动衰减预测关系式可用于香港地区。以50%概率时的中值对中国强震记录的对比, 本研究所提供的经验期望预测关系式, 能包络实际的资料。因此, 用此地震动衰减预测模式对香港地区地震危险性进行评估, 将会得到相对保守地震动预测值。通过香港地区基岩地震动危险性分析和计算, 参照中国大陆地震设防标准, 进行了基岩设计参数确定和区划。以年概率P=0.02、P=0.002、P=0.0004三个概率标准, 对应的地震动重复周期大约分别约为50a, 500a, 2500a的基岩PGA和反应谱, 作为香港地区基岩上构筑物和建筑物可选的基 相似文献
10.
This paper presents an investigation into various factors that may affect the ground response to multi-directional earthquake loading, focusing mainly on the behavior of vertical ground motion and its relation with the horizontal counterpart. The factors investigated herein include the intensity of input motion and the associated soil nonlinearity, the location of input motion (rock outcrop versus bedrock), the variation of water table, and the damping property of soil. Influence of these factors is studied on the characteristics of site amplification in both vertical and horizontal directions, the response spectra of vertical and horizontal ground surface motions, the spectral ratio between the two components (V/H) at the ground surface, and the distributions of stresses and strains in the ground. One of the main results is that varying water table can bring about a significant impact on vertical motion and the relationship between vertical and horizontal motions. The surface response spectral ratio (V/H) can largely exceed the rule-of-thumb value of 2/3 at low periods with lowering the water table, but does not appear to be substantially affected at long periods. 相似文献
11.
通过对2011年新西兰发生的6.3级地震中获取的硬土场地、软土场地和液化场地强震记录实测资料进行分析,研究包括3种类型场地的地震动特征及其相互关系。分析的强震记录为震中距小于50 km,且峰值大于0.05g的23个场地上的加速度记录,其中含3个硬场地、11个软场地和9个液化场地。3种类型场地上的放大系数谱对比分析表明,硬土场地、软土场地和液化场地上的地震动特征具有明显区别,三者层次清晰,差别显著,从地震动表现上液化场地已构成一个与常规场地并列的独立单元;液化场地减少地震动高频分量但同时对低频分量显著放大,与非液化场地相比,液化场地可使其上短周期结构反应减小一半,但同时可使其上长周期结构反应放大2.5～5.0倍;土层的液化对此次地震中克莱斯特彻奇市中心CTV大楼的破坏应有很大影响,大楼自振周期约为0.7 s,地震中土层液化使场地加速度反应谱卓越周期由0.1～0.3 s增到0.5～1.0 s,与大楼的自振周期趋于吻合,加重了大楼震害。以此为鉴,按现有规范中地震动的设计方法,如遇液化场地将对长周期结构给出明显危险的结果,因此从振动角度今后进行结构抗震设计时,可液化场地上的地震动应给予特殊考虑。 相似文献
12.
The strong ground motion from Athens, Greece 07/09/1999 earthquake has been recorded by eighteen (18) stations, fourteen (14) within the central Athens area and four (4) at the centers of nearby towns. The ground conditions for most of the recording sites were identified, based on previous geotechnical investigations carried out in the wider area of the sites, and consequently correlated to the seismic motion characteristics. Hence, it has been possible to evaluate the accuracy of different seismological methods for site characterization and also estimate soil effects on peak ground acceleration and elastic response spectra. In addition, preliminary estimates are drawn for the seismic motion characteristics at the epicentral area, where no strong motion recordings are available. The detailed soil profiles at the recordingsites are placed in the Appendix. 相似文献
13.
针对新型核电工程结构AP1000核岛结构设计地基中的5类非坚硬岩场地,即硬岩场地、软岩场地、上限软-中等土场地、软-中等土场地和软土场地,采用一维土层场地模型开展场地土和计算基底条件对设计地震动影响计算分析。分析中,场地模型的计算基底剪切波速分别取为700、1 100、2 438 m/s,计算基底输入地震动分别选择基于核电建设相关技术文件和规范规定的反应谱RG1.60谱、AP1000谱和HAD101/01谱（5个阻尼比）合成的人工地震动时程。计算分析表明：非坚硬岩场地会导致场地地震动峰值加速度及频谱特性显著变化,场地越软影响程度越显著;除软土场地外,场地对地震动峰值加速度和反应谱的影响均为放大作用,软土场地对地震动较低频段反应谱有放大作用,但对峰值加速度和较高频段反应谱具有强烈的减小作用;对于各类场地,计算基底及其剪切波速的变化均会导致地表地震动峰值及频谱特性明显甚至显著变化,其影响程度与计算基底剪切波速成正比;随着场地由硬变软,计算基底剪切波速的变化对场地地震动的影响程度大为减小,至软土场地几乎不产生影响。考虑到场地类型及计算基底选取对场地地震动的显著影响,我国核电厂建设引用AP1000标准设计时应合理分析场地的适宜性。 相似文献
14.
Himanshu Mittal Yih-Min Wu Ashok Kumar Arjun Kumar Babita Sharma 《Arabian Journal of Geosciences》2016,9(18):712
Uttarakhand, a state of India, is located in seismically active Himalayan region and in the proximity of plate boundaries. The effects of important ground motion parameters like magnitude, distance, and local geology and site conditions on acceleration response spectra are examined in Uttarakhand Himalayas in this work. A total of 447 strong ground motion histories (horizontal and vertical) from 42 earthquakes were selected. The results show that the shape of the acceleration response spectra is influenced by the local site conditions and regional geology. The studies are carried out for two categories of sites, i.e., rock sites and soft soil sites. The maximum average horizontal spectral amplification for rock sites is 2.7 at 0.1 s, while for soft soil sites, it is found to be 3.2 at 0.2 s. In the same way, the maximum average vertical spectral amplification for rock is found to be 2.7 at 0.1 s, while for soft soil, it is found to be 2.95 at 0.1 s. The average spectral amplification in vertical component also shifts from low period (rock) to high period (soft soil). The level of spectra increases with decrease in distance for rock sites as well as soft soil sites. When comparing different magnitude earthquakes in different geological conditions, the response spectra are found to follow each other up to 0.04 s, while for period greater than 0.04 s, the spectra of higher magnitude earthquake is observed on the higher side. For soft soil sites, spectra from different magnitude earthquakes are observed to follow each other up to 0.1 s, beyond which they get separated. 相似文献
15.
地震地面效应是地震工程和工程地震工作者共同关心的问题.前者着重研究地震动对上部结构的影响,后者则主要从事研究地震动对场地地基工程地质条件的影响.1979年对北京市区所作的一维地震反应分析,得出了土层厚度是影响地震地面运动的主要因素.输入地震动的卓越周期及其加速度峰值对反应谱形状的影响较时程曲线的影响明显.但一维方法只反映有界水平层及地震垂向上传.二维动力有限元地震反应分析改进了上述局限性,它可以研究任意形状的地基地质结构,能够反映埋藏基岩地形对地震波的折射、反射所产生的能量聚、散效应,埋藏基岩地形对地震地面效应的影响比上复松软土层土质不均匀的影响要大.超声地震模型实验首次引入工程地震学的研究课题中,得到了与上述数值分析方法相似的结果,并提出若干新问题.它提供了一种能够全面模拟震源—传播途径—场地地质结构的综合研究方法. 相似文献
16.
Intermediate-depth earthquakes in the Vrancea region occur in response to stress generation due to descending lithosphere
beneath the southeastern Carpathians. In this article, tectonic stress and seismicity are analyzed in the region on the basis
of a vast body of observations. We show a correlation between the location of intermediate-depth earthquakes and the predicted
localization of maximum shear stress in the lithosphere. A probabilistic seismic hazard assessment (PSHA) for the region is
presented in terms of various ground motion parameters on the utilization of Fourier amplitude spectra used in engineering
practice and risk assessment (peak ground acceleration, response spectra amplitude, and seismic intensity). We review the
PSHA carried out in the region, and present new PSHA results for the eastern and southern parts of Romania. Our seismic hazard
assessment is based on the information about the features of earthquake ground motion excitation, seismic wave propagation
(attenuation), and site effect in the region. Spectral models and characteristics of site-response on earthquake ground motions
are obtained from the regional ground motion data including several hundred records of small and large earthquakes. Results
of the probabilistic seismic hazard assessment are consistent with the features of observed earthquake effects in the southeastern
Carpathians and show that geological factors play an important part in the distribution of the earthquake ground motion parameters. 相似文献
17.
Strong ground motion estimation in the Sea of Marmara region (Turkey) based on a scenario earthquake 总被引：1，自引：0，他引：1
We perform a broadband frequency bedrock strong ground motion simulation in the Marmara Sea region (Turkey), based on several fault rupture scenarios and a source asperity model. The technique combines a deterministic simulation of seismic wave propagation at low frequencies with a semi-stochastic procedure for the high frequencies. To model the high frequencies, we applied a frequency-dependent radiation pattern model, which efficiently removes the effective dependence of the pattern coefficient on the azimuth and take-off angle as the frequency increases. The earthquake scenarios considered consist of the rupture of the closest segments of the North Anatolian Fault System to the city of Istanbul. Our scenario earthquakes involve the rupture of the entire North Anatolian Fault beneath the Sea of Marmara, namely the combined rupture of the Central Marmara Fault and North Boundary Fault segments. We defined three fault rupture scenarios based on the location of the hypocenter, selecting a preferred hypocentral location near a fault bend for each case. We analysed the effect of location of the asperity, within the Central Marmara Fault, on the subsequent ground motion, as well as the influence of anelasticity on the high-frequency attenuation characteristics. The fault and asperity parameters for each scenario were determined from empirical scalings and from results of kinematic and dynamic models of fault rupture. We calculated the resulting time series and spectra for ground motion at Istanbul and evaluated the sensitivity of the predictions to choice of model parameters. The location of the hypocenter is thus shown to be a critical parameter for determining the worst scenario earthquake at Istanbul. We also found that anelasticity has a significant effect on the regional attenuation of peak ground accelerations. Our simulated ground motions result in large values of acceleration response spectra at long periods, which could be critical for building damage at Istanbul during an actual earthquake. 相似文献
18.
Ahmad Nicknam Reza Abbasnia Yasser Eslamian Mohsen Bozorgnasab Ehsan Adeli Mosabbeb 《Journal of Earth System Science》2010,119(3):383-396
We determine the source parameters for 2003 (Mw 6.5) Bam, Iran, earthquake using an empirical Green’s function summation approach
to model ground motions recorded by two strong motion stations at approximately 45 km epicentral distance. We introduce a
genetic algorithm technique to optimize the fit to observed elastic response spectra. The proposed genetic algorithm technique
allows us to explore the sensitivity of the results to multiple source parameters, including hypocenter location, focal mechanism
(Strike and Dip), P-wave velocity in depth, fault dimension and rupture and healing velocities. 相似文献
19.
合理描述土体动力本构关系对场地设计地震动参数取值的准确性有显著影响。以苏州城区200 m深的钻孔剖面为研究对象,对比分析了一维等效线性波传分析法（ELA法）和基于修正Matasovic本构模型的多自由度集中质量非线性分析法（NLA法）给出的深厚场地地震反应,研究了基岩输入地震动特性和地震基岩面的选取对深厚场地地震反应的影响。结果表明：（1）随基岩地震动强度（PGA）的增大,ELA法给出的地表PGA呈单调递增的特征,而NLA法给出的地表PGA呈先快速增大后缓慢减小或几乎不变的趋势;（2）ELA法和NLA法给出的地表加速度反应谱（Sa谱）在短周期范围内存在明显差异,ELA法对基岩高频地震动具有显著的滤波效应,而NLA法对基岩高频地震动的影响表现为随基岩PGA的增大先放大后减小的特征;（3）随地震基岩面深度的增大,地表Sa谱的谱值呈现出稍许增大的趋势,但对周期T<0.1 s部分,NLA法给出的地表Sa谱的谱值则呈现出稍许减小的现象;（4）中、大震作用下,地表地震动持时不仅与基岩地震动特性有关,还与地震反应分析方法和地震基岩面的选取密切相关,NLA法能更合理地反映基岩地震动强度和上覆土层厚度对地表地震动持时的影响。 相似文献
20.
Amit Shiuly R. B. Sahu Saroj Mandal Narayan Roy 《Journal of the Geological Society of India》2018,91(4):400-410
Kolkata, capital of West Bengal, India, presently congested with moderate to high rise buildings, has undergone low to moderate damages due to past earthquakes. The city is situated on the world’s largest delta island with soft thick alluvial soil layer. In this study, an attempt has been made to study ground response due to a number of past earthquakes, 1897 Shillong earthquake, 1964 Calcutta earthquake and 2011 Sikkim earthquake, for the purpose of preliminary microzonation of the Kolkata city. For this, synthetic ground motions have been generated at bedrock level by stochastic method. By using 1D wave propagation technique, the synthetic ground motion has been computed at surface level for 144 borehole locations in the city. Contours of PGA, PGV and PGD parameters in the city have been drawn for these three earthquakes. Response spectra for these three earthquakes have also been computed and an optimum response spectrum has been determined. A good correlation has been obtained with predicted ground motion at surface level of the city with the reported intensity and damages occurred in buildings of Kolkata during past earthquakes. The scenario of simulated ground motion for the past three earthquakes depicts that Kolkata city is very much prone to damages even due to moderate far and near source earthquakes. 相似文献