共查询到18条相似文献，搜索用时 828 毫秒
1.
根据我国台湾地区西部的地质地貌特征和1999年集集MW7.6地震的震源参数,建立了三维速度结构模型和两类震源模型。基于地壳中断层的位错积累量和岩石破裂后应力应变的传播特性,采用三维有限差分法对双冬断层活动可能产生的近场脉冲型地震动进行了模拟研究。结果表明:走滑断层垂直于断层走向的水平分量和逆断层垂直分量的峰值速度较大;由方向性效应所产生的双向速度脉冲主要集中在垂直于断层滑动分量方向,而由滑冲效应所产生的单向速度脉冲则主要集中在平行于断层滑动分量的方向;受方向性效应和上盘效应的共同制约,近场脉冲型地震动呈不对称带状分布,速度脉冲多分布在距离走滑断层迹线15 km和逆断层迹线10 km的范围内;速度反应谱在断层面的覆盖范围内沿破裂方向逐渐增大,且速度脉冲可能会对大型建筑物产生严重的剪切破坏。受凹凸体特性的影响,地震波场显示南投、台中和苗栗处于强地震动危险区。 相似文献
2.
初步分析了近断层速度脉冲的成因和特点,主要包括方向性效应、滑冲效应和上盘效应,并通过集集地震中27个近断层强震台的脉冲记录分析了断层破裂方向和滑移大小对地面运动峰值速度的影响。采用最小二乘法对速度脉冲的分布范围进行了回归分析,大于50 cm/s的速度脉冲主要聚集在断层距为10 km的近断层区域。对不同区域的三分量平均速度反应谱进行统计分析,表明近断层脉冲型地震动具有较大的特征周期和谱值,其中在垂直于断层走向的水平分量上尤为显著,这与断层剪切位错辐射效应的特征基本相符。针对脉冲型地震造成近断层地质灾害频发的现象,由共振效应分析了速度脉冲对边坡岩体的影响。近断层速度脉冲的研究可能对防震减灾、地震预警、震害评估有一定的参考意义。 相似文献
3.
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
4.
利用5个反映地震动频谱特征的周期(反应谱卓越周期Tp, 平滑化反应谱卓越周期To, 傅氏幅值谱平均周期Tm, 等效速度脉冲周期Tv和拟速度反应谱卓越周期Tpv), 对集集地震的近断层三分量地震动进行研究. 结果表明, 上盘地震动的频谱周期小于下盘地震动; Tp小于To和Tm, 且Tp反映的三分量之间的关系与To和Tm不同; 在地表断裂带的北端,Tv和Tpv所反映的近断层地震动长周期分量的频谱特征, 与走滑断层中方向性效应作用的规律相类似. 得出的定性或定量结论可以为近场抗震设计谱的建立与地震危险性区划研究提供参考. 相似文献
5.
首先基于有限断层破裂下的运动学震源模型,对比验证了三维谱元法对于近场地震动的模拟精度。 进而通过含盆地模型与不含盆地的一维水平成层模型的地震动强度之间和放大系数分布特征之间的对比,详细研究了直下型断层的破裂速度对盆地地震效应的影响。结果表明,盆地的存在会显著改变近断层地震动的分布特征,同时盆地内不同分量强地震动的分布特征变化较大。断层破裂速度对盆地地震效应影响显著,随破裂速度的增大盆地地震动强度逐渐增加,但不同分量上地震动强度的增加速率显著不同,受盆地效应的影响,放大系数表现出与强地震动不同的分布特征。盆地放大系数整体表现出随破裂速度的增加而减小的趋势,但不同分量放大系数所受影响程度差异明显。同时,盆地内地震动强烈放大区域的位置也受破裂速度的显著影响,但其总体上集中在断层两侧区域及垂直于破裂方向的盆地边缘附近。 相似文献
6.
近断层地震动非常复杂,受地壳介质和地表局部场地影响的同时,更受地震断层破裂尺度、断层面位错的发展过程、破裂速度、滑动方向等因素的影响。近断层地震动常具有震动集中性、速度脉冲、永久位移以及破裂的方向性和上/下盘效应等特征。其中,地震动速度脉 相似文献
7.
基于数值格林函数法的近场强地震动数值模拟方法,以1994年Northridge地震断层面上位错量的不均匀分布模式和该地区的地层剪切波速度结构为震源模型和计算模型,做了两个方面的模拟研究:(1)直立走滑断层(断层倾角为90°)情况下,模拟分析了有限断层单侧破裂模式和双侧破裂模式对强地震动特征——破裂方向性和上盘效应的影响;(2)对于倾斜断层(倾角为45°),模拟分析了正断层、逆断层和走滑断层情况下,单侧破裂模式对其强地震动主要特征——破裂方向性效应和上盘效应的影响.结果表明:断层的破裂方式直接影响着地表地震动峰值和矢量分布;在近场区无论直立断层还是倾斜断层,其地表地震动峰值分布所表达的破裂方向性效应显著,位于破裂传播前方的地震动强度大,反映了波前被压缩的趋势,破裂后方地震强度明显变小;倾斜断层引起的上盘效应明显,NS向分量和竖向分量的地表地震动峰值的最大值出现在上盘靠近断层迹线处,EW向分量的峰值在断层迹线两侧呈不对称分布,且逆断层引起的地震动峰值最大,走滑断层的次之,正断层的最小. 相似文献
8.
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
9.
近断层速度脉冲与震源机制的关系浅析 总被引：1，自引：1，他引：0
本文初步分析了近断层速度脉冲的成因和特点,主要包括方向性效应与滑冲效应,并通过中国台湾集集地震的脉冲记录,分析了断层破裂方向和位移大小等震源参数对脉冲强度的影响。此外,基于有限移动源理论,说明了断层辐射与速度脉冲分布的关系,并探讨了利用运动学震源模型研究近断层地震动对速度脉冲影响的技术路线;评述了7种典型的等效速度脉冲模型,建议进一步研究等效速度脉冲函数与震源机制之间的关系。最后,简述了不同类型的断层引起速度脉冲的差异,并推测了产生脉冲型地震动的下限条件,同时展望该研究在地震预警方面的可能性。 相似文献
10.
11.
近断层速度脉冲型地震动研究对揭示建筑结构的破坏机理、开展抗震设防以及抗震设计具有重要价值。首先,对速度脉冲成因进行了系统的总结,并探讨了区分方向性效应速度脉冲和滑冲效应速度脉冲的思路;其次,系统地介绍了近断层速度脉冲的识别方法,评述了各种脉冲识别方法的优缺点;然后,基于速度脉冲特性,探讨了前方向性效应对速度脉冲特性的影响以及速度脉冲对反应谱的放大作用;最后,对速度脉冲型地震动输入方法以及对结构响应研究进行了系统总结,探讨了速度脉冲型地震动输入的关键问题。基于丰富的理论研究,未来对于速度脉冲型地震动研究工作应当充分结合实际工程需求,推进理论成果的规范标准化与工程实践。 相似文献
12.
Pulse-like ground motion observed during the 6 February 2023 MW7.8 Pazarcık Earthquake (Kahramanmaraş, SE Türkiye) 
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下载免费PDF全文 Fan Wu Junju Xie Zhao An Chenghao Lyu Tuncay Taymaz Tahir Serkan Irmak Xiaojun Li Zengping Wen Baofeng Zhou 《地震科学（英文版）》2023,36(4):328-339
In this study, we analyzed 100 three-component strong ground motion records observed within 200 km of the causative fault of the 6 February 2023 MW7.8 Pazarcık (Kahramanmaraş) Earthquake in SE Türkiye. The wavelet method was utilized to identify and analyze the characteristics of pulse-like ground motions in the near-fault region, while considering the uncertainty of the pulse orientation during the analysis. Our investigation focused on the effects of the focal mechanism and rupture process on the spatial distribution, pulse orientation, and maximum pulse direction of the observed pulse-like ground motion. We also analyzed the amplitude and period of the observed ground pulses and the effect of long-period amplification on the ground motion response spectra. Our results indicated the following: (1) A total of 21 typical ground velocity pulses were observed during this earthquake, exhibiting complex characteristics due to the influence of the strike-slip mechanism and rupture directivity. Most ground pulses (17 out of 21) were recorded within 20 km of the fault, in a wide range of orientations, including normal and parallel to the fault direction. The waveforms exhibited unidirectional features, indicating the effects of left-lateral fault slip. Distinct pulses observed more than 20 km from the fault were mainly oriented normal to the fault. The waveforms were bidirectional with double- or multi-round trips as a result of rupture directivity. (2) The amplitudes of the observed pulses ranged from 30.5 to 220.0 cm/s, with the largest peak velocity of 220.0 cm/s observed at Station 3138. The pulse periods ranged from 2.3 to 14.5 s, with the longest pulse period of 14.5 s observed at Station 3116. The amplitude and period of the pulses observed during this earthquake were comparable to those of similar-magnitude global earthquakes. The amplitude of the pulses decreased significantly with increasing fault distance, whereas the pulse period was not significantly affected by the fault distance. (3) Compared with non-pulse records, the velocity pulse records had a pronounced amplification effect on the acceleration response spectra near the pulse period, with factors ranging from 2.1 to 5.8. The larger velocity pulses also significantly amplified the velocity response spectra, particularly over the long periods. This significant amplification effect of the pulses on the response spectra leads to empirical models underestimating the long-period earthquake ground motion. 相似文献
13.
近断层地震动脉冲特性在2个水平分量上具有差异,采用平方和开方法分析了近断层脉冲地震动双向地震作用下基础隔震结构和组合隔震结构的隔震层位移,并与近断层脉冲单向地震作用进行了对比分析,结果表明:若仅地震动加速度峰值大的分量或2个方向分量均存在明显速度脉冲,则产生的隔震层位移大于单向地震动;若仅地震动加速度峰值小的分量存在明... 相似文献
14.
Pulse-like ground motions are capable of inflicting significant damage to structures. Efficient classification of pulse-like ground motion is of great importance when performing the seismic assessment in near-fault regions. In this study, a new method for identifying the velocity pulses is proposed, based on different trends of two parameters: the short-time energy and the short-time zero crossing rate of a ground motion record. A new pulse indicator, the relative energy zero ratio(REZR), is defined to qualitatively identify pulse-like features. The threshold for pulse-like ground motions is derived and compared with two other identification methods through statistical analysis. The proposed procedure not only shows good accuracy and efficiency when identifying pulse-like ground motions but also exhibits good performance for classifying records with high-frequency noise and discontinuous pulses. The REZR method does not require a waveform formula to express and fit the potential velocity pulses; it is a purely signal-based classification method. Finally, the proposed procedure is used to evaluate the contribution of pulse-like motions to the total input energy of a seismic record, which dramatically increases the seismic damage potential. 相似文献
15.
As the forward directivity and fling effect characteristics of the near-fault ground motions, seismic response of structures in the near field of a rupturing fault can be significantly different from those observed in the far field. The unique characteristics of the near-fault ground motions can cause considerable damage during an earthquake. This paper presents results of a study aimed at evaluating the near-fault and far-fault ground motion effects on nonlinear dynamic response and seismic damage of concrete gravity dams including dam-reservoir-foundation interaction. For this purpose, 10 as-recorded earthquake records which display ground motions with an apparent velocity pulse are selected to represent the near-fault ground motion characteristics. The earthquake ground motions recorded at the same site from other events that the epicenter far away from the site are employed as the far-fault ground motions. The Koyna gravity dam, which is selected as a numerical application, is subjected to a set of as-recorded near-fault and far-fault strong ground motion records. The Concrete Damaged Plasticity (CDP) model including the strain hardening or softening behavior is employed in nonlinear analysis. Nonlinear dynamic response and seismic damage analyses of the selected concrete dam subjected to both near-fault and far-fault ground motions are performed. Both local and global damage indices are established as the response parameters. The results obtained from the analyses of the dam subjected to each fault effect are compared with each other. It is seen from the analysis results that the near-fault ground motions, which have significant influence on the dynamic response of dam–reservoir–foundation systems, have the potential to cause more severe damage to the dam body than far-fault ground motions. 相似文献
16.
近断层地震动的基本特征 总被引：43，自引：11，他引：43
本文对近断层地震动的基本特征作了详细分析,这些基本特征主要包括近断层强地震动的集中性、地表破裂、地面永久变形、破裂的方向性效应、近断层速度大脉冲和上盘效应。这些特征虽然在一次地震中不一定同时出现,但它们是已经被强震观测资料和数值模拟证实了的,在模拟和预测近断层地震动时,必须充分考虑这些特点,合理的近断层地震动模拟或预测模型和方法应当在结果中再现这些特点。 相似文献
17.
Saman Yaghmaei-Sabegh 《Journal of Seismology》2010,14(4):715-726
This paper implements a quantitative approach to detect pulse-like ground motions based on continues wavelet transform, which
is able to clearly identify sudden jumps in time history of earthquake records by considering contribution of different levels
of frequency. These analyses were performed on a set of time series records obtained in near-fault regions of Iran. Pulse-like
ground motions frequently resulted from directivity effects in near-fault area and are of interest in the field of seismology
and also earthquake engineering for seismic performance evaluation of structures. The results of this study basically help
us to establish a suitable platform for selecting pulse-like records, while performance evaluation of structure in near-fault
area will need to account. The period of velocity pulses as a key parameter that significantly affects structural response
is simply determined by using a pseudo-period of the mother wavelets. In addition, the efficiency of different types of mother
wavelets on classification performance and the features of detected pulse are investigated by applying seven different kinds
of mother wavelets. The analyses indicate that the selection of most appropriate mother wavelet plays a significant role in
effective extraction of ground motion features and consequently in estimation of velocity pulse period. As a result, the user
should be aware of what is selected as a mother wavelet in the analysis. The comparisons given here among different mother
wavelets also show the better performance of BiorSpline (bior1.3) basis from biorthognal wavelet families for the preferred
purpose in this paper. 相似文献
18.
利用日本K-NET和KiK-net强震动台网获取的距离发震断层100 km以内136个强震动台站的三分量加速度记录,研究熊本M_W7.0地震地震动的长周期特性.基于残差分析研究不同周期地震动的空间分布差异,将观测分析结果与美国NGA经验模型、汶川和芦山地震观测结果进行对比,揭示此次熊本地震近场强震动的长周期特点及其形成机理.研究结果表明:(1)虽然总体上此次地震的近场地震动水平与美国NGA-West2经验模型的预测结果接近,但周期2 s以上地震动的分布在断层不同方位有系统性差异,在断层的北东方位,周期2.0～10.0 s的反应谱高于NGA-West2经验模型的预测结果,在西南方位,谱值低于经验预测模型.(2)我们认为此次地震2.0～10.0 s的长周期地震动的空间分布差异主要受破裂方向性的影响,在破裂传播的正前方,周期T=2.0 s,3.0 s,5.0 s,7.5 s和10.0 s的加速度谱被放大到整体观测平均水平的1 4～2.0倍.从周期T=2.0 s到10.0 s,破裂向前方向的放大作用和破裂反方向的减弱作用均有所增强,此次地震观测到的速度大脉冲记录均位于断层的东北方位,这与方向性脉冲的产生机理相吻合,速度大脉冲对加速度反应谱有显著的长周期放大作用,放大倍数值可以超过4.0,放大作用的影响主要位于脉冲的特征周期T_p附近.(3)近断层记录在建筑结构敏感的周期(0.5～2.0 s)的反应谱达到芦山地震的3～6倍,虽然与芦山地震震级接近,此次地震近断层地震动破坏力大大超过了芦山M_W6.8地震,甚至超过了汶川W_W7.9地震,这种长周期特点应该引起工程抗震设计和相关研究人员的重视. 相似文献