共查询到17条相似文献，搜索用时 171 毫秒
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近年来,地脉动水平/竖向谱比法广泛应用于获取场地卓越频率工作中,但在指示地震动放大系数方面是偏小的。利用KiK-net台网403个台站共21万余组数据,通过对比分析地脉动水平/竖向谱比MHVR和地震动水平/竖向谱比EHVR,发现二者的谱形和峰值频率基本一致,但幅值存在差异。根据MHVR谱形将场地分为6类,建立将MHVR修正为EHVR的经验方法。当MHVR有可解释的峰值时,实测EHVR和修正后MHVR预测值一致性提高。地震动峰值加速度在40 cm/s2以下时,EHVR受场地非线性的影响较小,利用MHVR及其修正方法可有效估计EHVR。 相似文献
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本文收集了从南北地震带川滇甘陕地区263个有详细场地资料的强震台站获得的802组强震动记录,按照场地、震级和震中距等因素统计分析了竖向与水平向加速度反应谱比的形状以及不同场地、震级和震中距下不同周期段内的谱比平均值,并与建筑抗震规范GB50011—2010规定的0.65进行了比较。结果表明:竖向与水平向加速度反应谱比受场地、震级和震中距等因素的影响; Ⅰ类和Ⅱ类场地在全周期段的谱比均值基本上大于0.65;无论何种分组情况谱比均值在0.1—1.0 s周期范围内基本低于定值0.65,周期大于1.0 s的谱比均值基本上远高于0.65。因此对于大部分抗震规范直接把竖向地震作用取为水平向地震作用的0.65倍,有待商榷。本文建议根据水平向反应谱的标定方式来确定现有竖向强震动记录的竖向地震作用。 相似文献
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随着我国强震记录的积累,利用强震记录进行工程场地抗震设防研究成为必然。使用滇西南地区2007—2011年间强震台网记录到的强震动记录数据,研究使用水平/垂直谱比法(H/V)处理强震数据时的几个影响因素。通过研究发现:在使用H/V谱比法进行场地地震效应研究时,强震记录和地脉动记录存在较大的不同;使用强震记录可以获得更多的震源和台站场地参数信息,但这同时也相应增加了强震数据使用时的难度。比较国内外学者使用强震数据进行场地地震效应的研究成果,分析在使用强震数据时存在的问题,最终给出使用强震记录研究场地效应的建议。 相似文献
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显著的竖向地震动是近断层地震动区别于远场地震动的重要特征之一,为更合理地确定竖向地震动作用,研究了近断层区域竖向地震动的反应谱特征及其与水平向反应谱比值的影响因素.首先,选取1952—1999年世界范围内震级在M5.4—7.6之间的18次地震的地震动记录,研究竖向地震加速度反应谱及其与水平向加速度反应谱比值特征;然后统计分析了断层距、场地条件、震级以及断层机制对竖向与水平向加速度反应谱比的影响.结果表明,一般情况下竖向加速度具有更丰富的短周期分量,并且竖向加速度反应谱衰减较慢;断层距在20km以内的近断层区域、软弱土层场地、中等震级地震和逆断层大震级中长周期范围等条件下,具有较大的竖向与水平向加速度反应谱比值;在近断层区域的结构抗震设计中应充分考虑竖向地震动的影响. 相似文献
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竖向地震动加速度反应谱特性 总被引：3，自引：0，他引：3
以33次地震中的地表地震动记录为数据基础,考虑场地条件、震级和距离的影响,分别对竖向地震动的加速度规准化反应谱和双规准化反应谱进行了研究。结果表明,规准反应谱明显受到场地条件、震级和震中距的影响,不同场地、距离和震级的平均规准反应谱之间差别显著;相比较而言,不依赖于场地、距离和震级的平均双规准反应谱之间却表现出良好的规律性和一致性。双规准反应谱的统一特性可以为竖向地震动设计谱的预测提供参考依据。 相似文献
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强震动记录H/V谱比法自提出以来,已广泛应用于地震工程各研究领域中。但对数据处理的2个关键环节——Taper预处理及傅氏谱平滑未有详细研究。因此,本文针对强震动记录H/V谱比法计算涉及的重要数据处理过程,对四川地区19个强震动台站在汶川地震余震中获取的642组强震动记录开展研究。研究实例表明:S波H/V谱比振幅在周期 < 1s时高于全时程,论证计算H/V谱比时截取S波窗口的必要性;S波窗口的截断会引起傅里叶振幅谱的边瓣效应,若不加以处理,将显著影响低频部分H/V谱比结果,Taper预处理对于消除这种截断误差具有良好效果;在兼顾平滑效果及卓越周期识别准确度的基础上,通过不同带宽的Parzen窗试算,认为0.5Hz带宽宜用于傅里叶H/V谱比曲线平滑。 相似文献
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2012年9月7日云南昭通彝良发生了Ms5.和、Ms5.6级两次地震,此次地震引发了极其严重的滑坡和崩塌等地震地质灾害,同时地震波放大效应还引起高烈度异常区。利用彝良地震烈度圈内6个台站记录到的主震加速度时程,通过截取S波窗,采用标准谱比法和水平垂直谱比法研究其场地地震动反应。结果表明:两种方法能给出较为一致的谱比曲线和卓越频率,但场地反应数值差异较大,标准谱比法的结果受到参考台站自身场地反应的影响;靖安台的软弱土层对地震动的放大作用较为显著,是造成烈度异常的主要原因。 相似文献
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采用汶川地震强余震26个强震动台站记录,基于H/V谱比法,计算台站场地的强、弱震作用下场地卓越频率之比R_(fp)和体现强、弱震作用下场地H/V谱比曲线差异程度的DNL,进而识别并分析场地非线性反应特征。结果显示,R_(fp)、DNL与PGA之间存在显著相关性;其中10个台站出现明显的场地非线性反应特征;大部分台站发生场地非线性反应的PGA阈值为100 cm/s~2,部分为50 cm/s~2;实例证明,因某些台站不易通过H/V谱比法识别场地卓越频率,因此采用R_(fp)识别场地非线性反应具有一定局限性。 相似文献
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现有场地对地震动的放大作用分析中,常采用观测得到正交方向的HVSR和SBSR的矢量合成结果表征场地放大作用,而不考虑放大作用的方向相关性。为研究不同地震作用下场地放大作用的方向相关性,采用多向HVSR和多向SBSR及谱比峰值方向相关分布概率,以11次地震事件获得的地表、井下基岩记录作为数据,开展响嘡场地效应台阵场地对地震动放大作用的方向相关性分析。研究结果表明,常用的矢量合成法分析结果与多向谱比上包络曲线法分析结果存在差异,前者存在忽略部分峰值的可能;多向谱比的极坐标等高线图可较直观地体现场地对地震动放大作用的方向相关性特征,但不同多向谱比表现存在差异;多向谱比峰值方向分布概率可较好地定量分析放大作用峰值在不同方向上的差异,但不同地震事件存在差异,不同的多向谱比存在差异。可采用多向谱比上包络曲线法分析场地放大作用,除可避免矢量合成法引起的误估外,也可更好地分析实际场地频率-方向相关的放大作用。 相似文献
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A. A. Panou N.P. Theodulidis P.M. Hatzidimitriou A.S. Savvaidis C.B. Papazachos 《Pure and Applied Geophysics》2005,162(5):891-912
In the framework of an ambient noise measurement project in the downtown district of the City of Thessaloniki (Northern Greece), several tests and evaluation of noise recordings were performed in selected sites. This data set was processed and compared with previous results for the same sites in terms of horizontal-to-vertical (H/V) spectral ratio obtained from weak and strong motion earthquake data. The recording system used was tested against a reference one. Finally, systematic ambient noise measurements were performed at eight sites in the citys downtown area, to evaluate diurnal and seasonal variations. It was concluded that the recording system used was reliable and the ambient noise H/V spectral ratios were in good agreement with relevant results previously obtained. Diurnal variation of the ambient noise H/V spectral ratio showed that it is preferable to perform measurements during the calm hours of the day, when man-made noise is relatively low. However, no systematic seasonal fluctuation effect on the ambient noise H/V spectral ratio was identified. 相似文献
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S. Molnar J. F. Cassidy S. Castellaro C. Cornou H. Crow J. A. Hunter S. Matsushima F. J. Sánchez-Sesma A. Yong 《Surveys in Geophysics》2018,39(4):613-631
Nakamura (Q Rep Railway Tech Res Inst 30:25–33, 1989) popularized the application of the horizontal-to-vertical spectral ratio (HVSR) analysis of microtremor (seismic noise or ambient vibration) recordings to estimate the predominant frequency and amplification factor of earthquake shaking. During the following quarter century, popularity in the microtremor HVSR (MHVSR) method grew; studies have verified the stability of a site’s MHVSR response over time and validated the MHVSR response with that of earthquake HVSR response. Today, MHVSR analysis is a popular reconnaissance tool used worldwide for seismic microzonation and earthquake site characterization in numerous regions, specifically, in the mapping of site period or fundamental frequency and inverted for shear-wave velocity depth profiles, respectively. However, the ubiquity of MHVSR analysis is predominantly a consequence of its ease in application rather than our full understanding of its theory. We present the state of the art in MHVSR analyses in terms of the development of its theoretical basis, current state of practice, and we comment on its future for applications in earthquake site characterization. 相似文献
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Deamplification of strong motion and the increase of the effective period of soil deposits are typical nonlinear effects; we seek them in SMART1-array data by applying the horizontal-to-vertical spectral ratio (HVSR) technique. The recordings, from four soil and one rock stations, represent 23 earthquakes (ML 4.9–7.0); PGA varies between 20–260 cm/s2. For each station, mean HVSR curves are calculated for two PGA ranges: <75 cm/s2 and >100 cm/s2 (weak and strong motion). At the soil stations, the “weak” (linear) and “strong” (nonlinear) responses are significantly different. Below 1–1.8 Hz, the nonlinear response exceeds the linear one. Above 2 Hz, the nonlinear response drops below the linear one and above 4–6 Hz below unity (deamplification). From 10 to 16 Hz, the two responses converge. One soil site shows significant negative correlation between resonance frequency and ground acceleration. Such behaviour agrees with other empirical studies and theoretical predictions. Our results imply that the HVSR technique is sensitive to ground-motion intensity and can be used to detect and study nonlinear site response. 相似文献
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局部场地条件对地震动特性影响显著,深厚的软弱覆盖层引起的地震动场地效应会显著放大中长周期反应谱。采用谱比法,对2020年7月12日唐山古冶5.1级地震中获得的部分强震动记录进行统计,发现在本次地震中北京城区的地震动场地效应显著,深厚覆盖层明显放大了加速度反应谱,在T=1.2 s左右反应谱放大倍数可达4.0,说明北京地区的场地和盆地效应使得远场地震动的中长周期成分显著放大。此外,发现参考基岩场地记录是否与土层场地处遭受的基岩地震动一致,仍然是制约统计结果可靠性的关键因素。 相似文献
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A. Moya V. Schmidt C. Segura I. Boschini K. Atakan 《Soil Dynamics and Earthquake Engineering》2000,20(1-4)
Site effects for 11 selected locations were determined in the capital city of Costa Rica. We used a strong motion network made of eight K2 and three SSA accelerographs. The network recorded more than 60 earthquakes in the magnitude range from 2 to 5 during a period of nine months. The site effects were determined using the sediment-to-bedrock spectral ratio (SBSR) and the horizontal-to-vertical spectral ratio (HVSR) techniques and a time window 4 s beginning from the S-wave arrival. The result suggests that the amplification in the capital city is to be in the range from 2.0 to 3.0. The fundamental frequencies were found to be high in the southern and eastern part of the study area and low in the northern and western part. A possible topographic effect was also observed for one of the stations located nearby a river canyon. The results from earthquake data were compared with the ones obtained from noise data. The horizontal-to-vertical noise ratio (HVNR) technique was used to estimate the site effects using ambient noise. The fundamental frequencies were found to correlate very well between both sets of data; on the other hand, the amplitude given by the noise was observed to be always lower than the one derived from the earthquake data. 相似文献