共查询到19条相似文献,搜索用时 171 毫秒
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地形对地震动的影响比较复杂, 考虑地形放大效应的地震滑坡稳定性分析需要选择合适的地震动参数. 本文使用自贡地形影响台阵记录到的2008年汶川MS8.0地震主震加速度记录, 分析了地震动峰值加速度、 阿里亚斯烈度以及90%能量持时随地形高度的变化, 探讨了地形效应作用下峰值加速度和阿里亚斯烈度与地震动作用下斜坡稳定性的相关性. 结果表明: ① 地形场地对峰值加速度和阿里亚斯烈度均有显著的放大效应. 地形放大效应较为复杂, 其整体上随台站高度的增加而增大, 水平向的放大效应大于竖直向. 水平向峰值加速度的放大系数为1.1—1.8, 阿里亚斯烈度的放大系数为1.2—3.3; 竖直向相应放大系数分别为1.1—1.3和1.2—1.7. ② 地形对地震动持时也有一定的放大效应, 但不同高度、 不同分量的放大效应没有显著差异, 其放大系数均约为1.3. ③ 阿里亚斯烈度和峰值加速度均能很好地表征地形对地震动的影响, 与地震动对斜坡稳定性的影响具有很强的相关性. 与峰值加速度相比, 阿里亚斯烈度综合了地震动的多方面特征, 可以更好地表征地形对地震动的影响, 与地震动作用下斜坡稳定性的相关性更强. 相似文献
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2021年5月21日云南省大理州漾濞县发生MS6.4 地震,震中附近遭受了强烈地震破坏.为预测此次地震的地震动影响场,利用震源运动学破裂随机模型,基于随机有限断层三维地震动模拟方法,给出了此次地震中 28个触发强震动台站的三分量加速度时程模拟记录,并结合强震动观测记录,估计了此次地震的地震应力降及震源破裂过程,进一步模拟给出了此次地震中 2823 个虚拟观测点的三分量加速度时程.结果表明,模拟记录的峰值地面加速度(PGA)、峰值地面速度(PGV)与观测值接近,并体现了地震动峰值的衰减规律、近场饱和效应和破裂方向性效应;模拟与观测记录的 5%阻尼比拟加速度反应谱(PSA)的幅值接近、谱形相似,在0.05~10 s周期段,模拟记录可以很好地预测地震动.基于三分量模拟记录给出了漾濞MS 6.4 地震的仪器测定地震烈度图,与云南省地震局发布的烈度图接近,极震区烈度最高可达Ⅷ度,震源破裂方向性导致震中 SE方向的烈度普遍高于 NW方向,受局部场地条件影响沿洱海西侧出现高烈度异常区. 相似文献
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利用中国台湾省内222个强震动台站以及Palert地震预警系统520个台站所观测的三分量加速度记录,研究此次花莲M_W6.4地震近场强地震动空间分布和衰减特征,将观测结果与美国NGA-West2地震动经验预测模型进行对比,揭示此次台湾花莲地震近场地震动的长周期特点,基于回归残差分析研究地震动峰值加速度(PGA)、峰值速度(PGV)和不同周期地震动的空间分布差异,定量考察近场地震动的方向性效应.研究结果表明:(1)整体上此次地震的近场PGV观测值和周期1.0s以上的长周期加速度谱值与美国NGA-West2地震动预测模型结果接近,PGA观测值和周期小于1.0s的加速度反应谱略低于预测模型结果.从空间分布来看,周期1.0s以上的长周期地震动在断层的不同方位有系统性差异,在破裂传播前方(震中西南方位),周期大于1.0s时的反应谱明显高于美国NGA-West2地震动经验预测模型,在破裂传播后方(震中东北方位),周期大于1.0s时的反应谱低于经验预测模型,表明此次地震近场地震动具有显著的方向性效应.(2)破裂传播的方向性效应主要影响周期超过1.0s的长周期,而对PGA以及周期小于1.0s的短周期地震动影响较弱.在破裂传播前方,周期1.0~10.0s的加速度反应谱值被增强到整体观测平均水平的1.16~1.52倍;在破裂传播后方,周期1.0~10.0s的加速度反应谱值被减弱到整体观测平均水平的0.36~0.70倍.(3)此次地震破裂方向性效应的影响表现出明显的窄带效应,破裂方向性的影响(包括破裂传播前方的增强作用和破裂传播后方的减弱作用)在周期T=3.0s时达到最大,在该周期破裂传播前方的增强系数为1.52,破裂传播后方的减弱系数为0.36.从周期T=3.0s到10.0s,破裂方向性效应的影响随周期增大总体上呈减弱趋势,这与2016年日本熊本M_W7.0地震破裂方向性效应的影响特点显著不同. 相似文献
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2020年1月18—19日新疆喀什地区伽师县连续发生3次MS≥5.0地震,其中19日21时发生伽师县MS6.4地震。为更好地了解此次地震的强震动记录特征,分析了此次地震序列的强震动记录,从记录波形上看,位于近场区西克尔强震台获取较大峰值加速度,特别是垂直向有明显脉冲峰值,其水平向有明显脉冲地震动,脉冲周期约为2.78 s,速度脉冲峰值分别为38.1 cm·s-1和36.4 cm·s-1,反应了断层破裂的方向性效应。用谱比法分析场地的放大效应,在2 s左右有一个基本的共振周期。通过与喀什地区伽师县设计反应谱对比,西克尔台站的水平向地震动的反应谱远高于喀什地区8度罕遇地震设计反应谱。 相似文献
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为研究2016年8月24日意大利中部MW6.2地震的断层破裂方向性效应, 依据断层走向将强震动观测台站划分为SE和NW两组, 比较两组记录的地面峰值加速度PGA、 地面峰值速度PGV、 拟加速度反应谱PSA和重要持时DSR. 结果显示: NW组观测到的PGA, PGV和PSA普遍大于SE组, PGA和PGV的观测值与预测值的残差随方位角变化明显; NW组观测到的DSR值整体小于SE组, 由此推断此次地震存在明显的方向性效应. 在此基础上, 采用反演方法, 确定了该地震的震源为双向非对称破裂, 主破裂方向大约介于345°—360°之间, 主破裂长度约占整个破裂的70%—80%, 破裂速度为2.2—2.5 km/s, 反演结果印证了两组台站数据的地震动参数差异是由断层破裂方向效应所引起的. 相似文献
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2016年10月30日意大利中部发生了MW6.6地震,这是继8月24日MW6.2地震后的又一次浅源破坏性地震,意大利国家强震台网在此次地震中获得了丰富的强震动三分向加速度记录。本文从工程强震动数据中心下载了三分向加速度记录,经基线校正和滤波等常规数据处理后发现,强震动体现出明显的方向性效应。根据震源机制解将强震动台站分为破裂前方区域的NW组和破裂后方区域的SE组,采用最小二乘法回归了不同分组的地震动峰值加速度、反应谱和持时的衰减规律,得出断层破裂方向性对地震动参数的幅值影响较大,在断层距相同的情况下,破裂前方区域的加速度和加速度反应谱幅值均高于破裂后方区域,而破裂前方区域的地震动持时远小于破裂后方区域,破裂方向性显著。 相似文献
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利用中国强震动台网获得的汶川地震近断层强震动数据,研究汶川地震近断层地震动的强度和频率的非平稳特征,并对其非平稳特征的原因进行初步分析.研究表明近断层地震动强度和频率表现出很强的非平稳特性,这种非平稳特征主要受震源破裂机制、台站方位和局部场地条件的影响.破裂传播正向和反方向上地震动强度和频率的时间过程有显著的不同.在破裂正向上,地震动加速度记录表现为大幅值、短持时的强度过程,强度过程的持续时间为15 s左右,加速度时程的主要周期约为0.4 s,地震动速度时程有较明显的速度脉冲,脉冲周期可以达到8 s;在破裂的反方向上,地震动强度过程的时间跨度长达90 s,加速度记录的主要周期约为0.6 s,速度时程中没有明显的脉冲.小波功率谱的分析结果表明破裂正向上速度脉冲表现为在很小的时间尺度和频域内能量的集中,值得注意的是,观测到的速度脉冲的周期长达8 s,比Chi-Chi地震和Kobe地震中观测到的脉冲周期要长,这可能与汶川地震的震级相对较大有关. 相似文献
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选择台湾集集地震和美国北岭地震的近断层地震动记录作为输入,考察了近断层地震动破裂向前方向性与滑冲效应引起的两种不同速度脉冲运动对单自由度体系和长周期橡胶支座隔震建筑结构抗震性能的影响.反应谱分析表明,破裂向前方向性与滑冲效应对工程结构地震响应的影响是随结构周期变化的.在中短周期段,含破裂向前方向性效应地震动的谱加速度值大于含滑冲效应地震动的谱加速度值;而在长周期段,含滑冲效应地震动的谱加速度大于含破裂向前方向性效应的谱加速度值.并且,与无脉冲地震动作用相比,含破裂向前方向性与滑冲效应脉冲的近断层地震动作用下隔震建筑的地震响应显著增大.滑冲效应引起的速度脉冲使隔震建筑底部的层间变形和楼层剪力明显增大,这意味着滑冲效应脉冲比向前方向性效应脉冲对长周期建筑结构的破坏更具危害性. 相似文献
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近断层地震动作用下土质边坡动力响应研究 总被引:1,自引:0,他引:1
根据汶川地震中滑坡多沿断层分布的特点,利用FLAC有限差分软件建立了一个土质边坡动力数值分析模型,分别研究了具有向前方向性效应、滑冲效应和无速度脉冲的近断层地震动作用下边坡的动力响应.结果表明:含速度脉冲地震动对边坡的破坏作用远强于无速度脉冲地震动,且具有滑冲效应的地震动引起的边坡动力响应稍大于向前方向性效应地震动.近断层地震作用下,边坡水平方向绝对峰值加速度分布存在沿高程放大效应.具有向前方向性效应的地震动会增强边坡加速度的高程放大效应而具有滑冲效应的地震动则在一定程度上削弱了这种放大效应,且边坡中下部绝对峰值加速度值相对于向前方向性效应地震动和无速度脉冲地震动引起的绝对峰值加速度值较大. 相似文献
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2015年4月25日尼泊尔廓尔喀地区发生MS8.1级地震,本文分析了加德满都强震台站的强地震动记录特征,其水平向地震动表现为明显的脉冲地震动,脉冲周期约为6.0s,反映了近场地震动的方向性效应;处于深厚沉积层上的加德满都谷地对地震动有一定的放大作用,且主震的场地峰值频率向低频段偏移,出现明显的场地非线性反应;采用随机有限断层方法模拟的空间地震动分布与宏观地震烈度图符合较好,可以为分析宏观震害提供参考;通过与尼泊尔设计反应谱对比,得出在短周期与长周期段,加德满都台站的水平向地震动的反应谱远高于设计反应谱,说明即使严格按照尼泊尔建筑抗震规范设计施工的建筑结构也难以抵御此次地震的破坏。 相似文献
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Rupture directivity effect on strong ground motion during the 12 May 2008 MW7.9 Wenchuan earthquake
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We focus here on the rupture directivity effect on the spatial distribution and attenuation characteristics of near-field ground motions during the 2008 MW7.9 Wenchuan earthquake. We examine the difference between the observed ground motions in and opposite the rupture directions and compare them with Next Generation Attenuation-West2 (NGA-West2) ground motion prediction models. The isochrone directivity predictor is used to quantify the band-limited nature of the rupture directivity effect on strong ground motion. Our results show that the observed peak ground velocity (PGV) and spectral accelerations of periods of 1.0 s and longer are significantly amplified in the rupture direction, but de-amplified in the opposite direction affected by rupture directivity effect of this event. In contrast, the effect of rupture directivity on the observed peak ground acceleration (PGA) and periods of shorter than 1.0 s are relatively weak. The rupture directivity of this event shows clear period dependent and band limited characteristics with the strongest effect occurring around the period of 7.5 s. 相似文献
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利用2014年鲁甸MS6.5地震断层距小于300 km的32个自由场地观测台站的地震动加速度记录,分析了地震动峰值加速度(PGA)和峰值速度(PGV)的空间分布特征,并对已有地震动衰减模型中的NGA-West2四个模型和1个中国川藏区模型进行了比较分析.研究表明,地震动PGA和PGV衰减最快的方向与断层主破裂方向一致.在整个断层距(Rrup)范围内大多数台站的地震动PGA、PGV和加速度反应谱值(Sa(T=0.1、5.0 s))均位于NGA-West2四个模型预测曲线的±1倍标准差之外.PGA、PGV和Sa(T=5.0 s)的事件内残差均值在-1.43~-0.74之间.Sa(T=0.01~5.0 s)事件内残差均值在整个距离范围内均表现出系统性偏负.NGA-West2四个模型的PGA事件内残差的空间分布特征相似,其最大正值和最大负值分布区域的震源-场地方位角约为-90°和90°,与主破裂断层方向垂直,所处地势较为平坦且台站场地VS30相对较大.NGA-West2四个模型总体上会较大地高估鲁甸地震整个断层距范围内各个周期尤其是短周期(T < 1.0 s)的地震动加速度反应谱值.考虑本地区实际地震资料的中国川藏区地震动衰减模型也会在一定程度上高估鲁甸地震大多数台站的地震动加速度反应谱值,但是相对于NGA-West2四个模型,其预测值更接近鲁甸地震的实际观测值.
相似文献14.
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Empirical attenuation relationship for Arias Intensity 总被引:1,自引:0,他引:1
Arias Intensity is a ground motion parameter that captures the potential destructiveness of an earthquake as the integral of the square of the acceleration–time history. It correlates well with several commonly used demand measures of structural performance, liquefaction, and seismic slope stability. A new empirical relationship is developed to estimate Arias Intensity as a function of magnitude, distance, fault mechanism, and site category based on 1208 recorded ground motion data from 75 earthquakes in active plate‐margins. Its functional form is derived from the point‐source model, and the coefficients are determined through non‐linear regression analyses using a random‐effects model. The results show that for large magnitude earthquakes (M > 7) Arias Intensity was significantly overestimated by previous relationships while it was underestimated for smaller magnitude events (M ? 6). The average horizontal Arias Intensity is not significantly affected by forward rupture directivity in the near‐fault region. The aleatory variability associated with Arias Intensity is larger than that of most other ground motion parameters such as spectral acceleration. However, it may be useful in assessing the potential seismic performance of stiff engineering systems whose response is dominated by the short‐period characteristics of ground motions. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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计算机仿真模拟设定地震断层动态破裂传播和近断层强地表运动响应的结果表明, 对于特征地震而言,近断层附近的地表运动特征与断层破裂传播的方向性有着强烈的依赖关系. 当场地(观测点)至断层的距离给定时,正向于破裂传播方向的场地(场地A)的地表质点运动(位移、速度、加速度),远远大于震中附近(场地B)和反向于破裂传播方向的场地(场地C)的地表质点运动,而且沿断层垂直分量所辐射的SH波的传播起到了主导作用. 对应于场地A,B和C,统计分析结果表明,峰值加速度的几何平均值之比为2.15:1.5:1, 而且各自的均方差分别为0.12, 0.11和0.13. 如果将所得的研究结果应用于概率地震危险性分析中,对于较低的年超越频度,近断层附近的地表峰值加速度的估算值可下降15%~30%. 因此,考虑到断层破裂传播方向性对地表运动的影响,区域衰减曲线的回归分析模型应该给予恰当的修正. 相似文献
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The effect of seismic super-shear rupture on the directivity of ground motions using simulated accelerations of a vertical strike-slip fault model is the topic of this study. The discrete wave number/finite element method was adopted to calculate the ground motion in the horizontal layered half space. An analysis of peak ground acceleration (PGA) indicates that similar to the sub-shear situation, directivity also exists in the super-shear situation. However, there are some differences as tbllows: (1) The PGA of the fault-normal component decreases with super-shear velocity, and the areas that were significantly affected by directivity in the PGA field changed from a cone-shaped region in the forward direction in a sub-shear situation to a limited near-fault region in a super-shear situation. (2) The PGA of the fault-parallel and vertical component is not as sensitive as the fault-normal component to the increasing super-shear velocity. (3) The PGA of the fault-normal component is not always greater than the fault-parallel component when the rupture velocity exceeds the shear wave velocity. 相似文献
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Characteristics of amplitude and duration for near fault strong ground motion from the 1999 Chi-Chi, Taiwan Earthquake 总被引:2,自引:0,他引:2
A great number of free-field ground motion records are obtained during the 1999 Chi-Chi, Taiwan, earthquake. Records from 130 near fault free-field stations within 55 km to the causative fault surface are used as database, and characteristics of earthquake peak ground acceleration, velocity, displacement and duration are analyzed. According to this study, near fault ground motions are strongly affected by distance to fault, fault rupture directivity, site condition, as well as thrust of hanging wall. Compared with empirical strong ground motion attenuation relations used in China, US and Japan, the PGAs and PGVs recorded in this earthquake are not as large as what we have expected for a large earthquake as magnitude 7.6. However, the largest PGV and PGD worldwide were recorded in this event, which are 292 cm/s and 867 cm, respectively. Caused by nonlinear site effects of soil, peaks and corresponding ratios on E-class site were markedly different from those on other sites. Just as observed in historic earthquakes, fault rupture directivity effects caused significant differences between peaks of ground motion of two horizontal components, but took very slight effects on the duration of ground motion. The significant velocity pulses associated with large PGVs and PGDs, as well as large permanent displacements, which may result from the large thrust of the hanging wall, became the outstanding character of this event. Based on this study, we point out that 3D waveform modeling is needed to understand and predict near fault ground motion of large earthquakes. 相似文献
19.
《中国科学D辑(英文版)》2008,(12)
The Wenchuan earthquake of 12 May 2008 is the most destructive earthquake in China in the past 30 years in terms of property damage and human losses. In order to understand the earthquake process and the geo-morphological factors affecting the seismic hazard, we simulated the strong ground mo-tion caused by the earthquake, incorporating three-dimensional (3D) earth structure, finite-fault rupture, and realistic surface topography. The simulated ground motions reveal that the fault rupture and basin structure control the overall pattern of the peak ground shaking. Large peak ground velocity (PGV) is distributed in two narrow areas: one with the largest PGV values is above the hanging wall of the fault and attributed to the locations of fault asperities and rupture directivity; the other is along the north-western margin of the Sichuan Basin and caused by both the directivity of fault rupture and the ampli-fication in the thick sediment basin. Rough topography above the rupture fault causes wave scattering, resulting in significantly larger peak ground motion on the apex of topographic relief than in the valley. Topography and scattering also reduce the wave energy in the forward direction of fault rupture but increase the PGV in other parts of the basin. These results suggest the need for a localized hazard as-sessment in places of rough topography that takes the topographic effects into account. Finally, had the earthquake started at the northeast end of the fault zone and ruptured to the southwest, Chengdu would have suffered a much stronger shaking than it experienced on 12 May, 2008. 相似文献