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1.
国内外规范中推荐或强制规定竖向地震动取为剪切反应谱的1/2～2/3,但该规定如何改进使其更合理已成为一重要课题。首先,对其研究现状简单总结,给出了可处理辐射阻尼、地震动相位特性、计算高效的二维波动显式有限元等效线性化程序ELPSV编制的必要性,然后进行了分析。初步研究表明,竖向地震动强度对周期在0.3 s以下的地表剪切反应谱有一定的影响,而高于0.3 s部分影响轻微。竖向地震动强度对斜坡场地的竖向地震反应及地表竖向反应谱影响显著,按规范的取值将偏于不安全。受地形条件影响,坡顶剪切地震反应会比坡脚反应要大,而竖向地震反应并不明显。土层边界面的地震反应要比周围反应要低,交界面效应明显。软斜坡场地地震反应特性除场地竖向地震反应自下而上先增加后减小的规律外,其他情形与硬斜坡场地的规律基本一致。该结果定量反映了竖向地震动的影响程度,为斜坡场地上考虑竖向地震动的建（构）筑结构的抗震设计提供了有益的基础。 相似文献
2.
Urban earthquake scenario requires compilation and interpretation of topographical, geological, geotechnical, macroseismic, and instrumental data, along with identification of proper ground motion prediction and site response analysis. Within the intensive city planning and infrastructure improvement of Baku city (the capital of Azerbaijan), and due to land and water instabilities, intensified landslides, and increasing seismic activity, Absheron peninsula has turned into one of the strategic earthquake case studies, representing exposure to earthquake hazard in the region. The last strongest 25th November 2000 earthquake revealed that the peninsula was severely vulnerable to seismic events, since there was a lack of public awareness of seismic disaster and its consequences, and there were not any preventive measures which might have been derived from the scenario-based simulations and prediction of strong motion distribution over the area. In the present work, integrated analysis of seismicity, engineering geology, geomorphology, topography, and site response is used to model strong motion dynamics in terms of peak ground acceleration distribution and intensity level for Absheron peninsula along with Baku city. The strong motion scenario of the 25th November 2000 earthquake shows that the larger area of the peninsula coincides with the VIII–IX intensity level, including Baku city. The scenario distribution can be valuable in all phases of the disaster management process. 相似文献
3.
We present an overview of our recent results on utilizing small earthquakes in the earthquake engineering practice. Site-specific ground motion time-histories of large earthquakes can be successfully simulated using recordings of small earthquakes which are often referred to as 'empirical Green's functions' in seismology. Another important practical problem is whether and how these observations can be used in seismic risk studies which are based on empirical attenuation relations for ground motion parameters. We study a possibility of extrapolating attenuation relations for small earthquakes, to larger magnitudes using the data from the Garner Valley downhole array in Southern California. Finally we introduce efficient ground motion processing techniques in frequency- and time-domains and apply them to site response estimation. 相似文献
4.
深度衰减效应对大型地下洞室群强震响应的影响分析 总被引：1，自引：1，他引：0
介绍了大型地下洞室群强震反应分析所需要输入地震波的选用原则,重点考虑了场地的深度衰减效应,同时提出了一种假设来确定地震危险性分析提供的峰值加速度的所在位置。选用了两组攀枝花实测地震记录,同时利用三角级数叠加法综合考虑了深度衰减效应,合成了一组人工地震动,使用ABAQUS软件对某水电站大型地下洞室群进行了二维非线性强震动力时程数值计算分析。结果表明：生成的地震波能较好地模拟地下洞室群的地震响应,深度衰减对地震响应结果有明显影响,不同频谱的地震波相对位移-时程差距较大,但频谱参数的影响还有待于深入研究。研究成果对大型地下洞室群地震动输入问题研究具有一定的指导意义。 相似文献
5.
H. Langer 《Natural Hazards》1990,3(2):125-139
The estimation of seismic loading requires both the featuring of the seismotectonic environment as well as a prognosis of site-specific strong ground-motion parameters. Due to the long recurrence times of larger events, there is a lack of high quality strong motion recordings at many sites. The use of seismograms obtained from different seismotectonic regions, additionally recorded under different subsoil conditions, poses several questions as to the significance of the assessment of seismic loading. A way to overcome these problems is the generation of synthetic seismograms, e.g. by the use of Boore's stochastic procedure. Subsoil conditions may be explicitly included in the simulation as proposed by Kunze et al. In this context, the seismotectonic environment forms the deterministic frame of any stochastic strong ground-motion simulation. In terms of Boore's approach, seismic moment, global stress drop, high frequency cut off, and focal depth act as controlling parameters. In order to achieve a more realistic assessment of possible seismic loading, a classification of seismoactive zones should account for parameter vectors as described above rather than for single parameters like magnitudes or intensities. A tool to attack this task may be found in cluster analysis, which is a type of pattern recognition based on statistical considerations. Crucial to this technique, however, is the use of properly estimated parameters, which still cause discussion in the seismological community. Problems and chances of the approach are discussed with examples from the Swabian Jura and the Rhine graben.Paper presented at the 21st General Assembly of the European Seismological Commission held in Sofia, 1988. 相似文献
6.
7.
强地震动作用下层状岩体破坏的物理模拟研究 总被引：4，自引：1，他引：3
岩体地震动力破坏现象是常见但研究较少的复杂课题。利用物理模拟试验,研究了层状岩体边坡在强地震动作用下的变形破坏问题。按结构面走向平行和垂直地震动方向,对不同岩体结构特征的模型施加不同的幅值和频率的水平向地震动荷载,进行岩体的振动破坏试验。结果表明,结构面空间展布方向与地震动荷载的相互关系不同、结构面软弱程度不同,岩体变形破坏的形式和分布特征也不相同。岩体的动力破坏主要是岩体结构的破坏,即岩体结构的宏观破坏和微观损伤,岩体结构特征是控制其动力变形破坏的主要因素。极大的不均匀性是岩体动力破坏的显著特点,这与大量极震区岩体破坏的现象类似。但岩体动力破坏模式的建立和定量的力学分析还需更多研究。 相似文献
8.
Estimation of seismic spectral acceleration in Peninsular India 总被引：6，自引：0，他引：6
Peninsular India (PI), which lies south of 24°N latitude, has experienced several devastating earthquakes in the past. However,
very few strong motion records are available for developing attenuation relations for ground acceleration, required by engineers
to arrive at rational design response spectra for construction sites and cities in PI. Based on a well-known seismological
model, the present paper statistically simulates ground motion in PI to arrive at an empirical relation for estimating 5%
damped response spectra, as a function of magnitude and source to site distance, covering bedrock and soil conditions. The
standard error in the proposed relationship is reported as a function of the frequency, for further use of the results in
probabilistic seismic hazard analysis. 相似文献
9.
Probabilistic seismic hazard analysis for Sumatra, Indonesia and across the Southern Malaysian Peninsula 总被引：1，自引：0，他引：1
Mark D. Petersen James Dewey Stephan Hartzell Charles Mueller Stephan Harmsen ArthurD. Frankel Ken Rukstales 《Tectonophysics》2004,390(1-4):141-158
The ground motion hazard for Sumatra and the Malaysian peninsula is calculated in a probabilistic framework, using procedures developed for the US National Seismic Hazard Maps. We constructed regional earthquake source models and used standard published and modified attenuation equations to calculate peak ground acceleration at 2% and 10% probability of exceedance in 50 years for rock site conditions. We developed or modified earthquake catalogs and declustered these catalogs to include only independent earthquakes. The resulting catalogs were used to define four source zones that characterize earthquakes in four tectonic environments: subduction zone interface earthquakes, subduction zone deep intraslab earthquakes, strike-slip transform earthquakes, and intraplate earthquakes. The recurrence rates and sizes of historical earthquakes on known faults and across zones were also determined from this modified catalog. In addition to the source zones, our seismic source model considers two major faults that are known historically to generate large earthquakes: the Sumatran subduction zone and the Sumatran transform fault. Several published studies were used to describe earthquakes along these faults during historical and pre-historical time, as well as to identify segmentation models of faults. Peak horizontal ground accelerations were calculated using ground motion prediction relations that were developed from seismic data obtained from the crustal interplate environment, crustal intraplate environment, along the subduction zone interface, and from deep intraslab earthquakes. Most of these relations, however, have not been developed for large distances that are needed for calculating the hazard across the Malaysian peninsula, and none were developed for earthquake ground motions generated in an interplate tectonic environment that are propagated into an intraplate tectonic environment. For the interplate and intraplate crustal earthquakes, we have applied ground-motion prediction relations that are consistent with California (interplate) and India (intraplate) strong motion data that we collected for distances beyond 200 km. For the subduction zone equations, we recognized that the published relationships at large distances were not consistent with global earthquake data that we collected and modified the relations to be compatible with the global subduction zone ground motions. In this analysis, we have used alternative source and attenuation models and weighted them to account for our uncertainty in which model is most appropriate for Sumatra or for the Malaysian peninsula. The resulting peak horizontal ground accelerations for 2% probability of exceedance in 50 years range from over 100% g to about 10% g across Sumatra and generally less than 20% g across most of the Malaysian peninsula. The ground motions at 10% probability of exceedance in 50 years are typically about 60% of the ground motions derived for a hazard level at 2% probability of exceedance in 50 years. The largest contributors to hazard are from the Sumatran faults. 相似文献
10.
Repeated earthquakes (EQs) are clear indication of alarming seismicity which can be witnessed across Indian subcontinent. Increase in population density with inappropriate construction practice repeatedly rise alarm that in comparison to damage scenarios experienced during previous major to great EQs in India, future catastrophes would be manifold. Performing regional seismic hazard as well as site response studies can possibly help in accurate estimation of probable future seismic scenario. Site class (SC) of EQ recording stations is an important part of both seismic hazard as well as site response analyses. In seismic hazard analysis, suitable attenuation relations are often selected based on comparison of recorded ground motion with proposed ground motion as per selected attenuation relation for the same SC. Thus, unless SC of recorded ground motions is known, suitability of selected attenuation relation cannot be validated. In addition, recent studies suggest that for same soil column, ground motion may amplify at the surface from minimal to very high depending upon input motion characteristics. Thus again, unless SC of recording station is not known, recorded ground motion cannot be considered with confidence as outcrop or base motion for region specific site response studies. In the present work, SC of eight recording stations located in Tarai region of Uttarakhand, India located adjacent to the Himalayan belt and which are part of PESMOS database, are established by three different methods namely; equivalent linear ground response analysis, generalized inversion technique and horizontal to vertical spectral ratio method. Collectively all these three methods suggest same SC for each of the eight recording stations including Roorkee, Rishikesh, Dehradun etc. Further, obtained SC based on the present study is considerably different from available SC as per PESMOS database. However, present findings are matching with recent published work. Obtained results can be very helpful in developing surface seismic hazard using regional ground motion records towards minimizing future EQ induced damages. 相似文献
11.
We evaluated the quality of seismic phase data from Indian seismological stations through the analysis of teleseismic travel
times reported during 1976–83 and infer that only WWSSN stations (NDI, SHL, POO, KOD) apart from GBA and HYB can be rated
satisfactory while the majority of stations (more than 40) produce very poor quality data sets. Detailed analysis of teleseismic
P-wave travel time residuals shows that while the average structure of the upper mantle beneath India has high velocity (negative
residuals) there are marked lateral variations. In particular, three zones of anomalous positive residuals (low velocity)
are observed: one beneath the north western part of the Deccan trap, the second covering the southernmost peninsula (granulite
terrain) and a third rather localized one, to the north of Delhi coinciding with Delhi-Haridwar ridge. New Delhi exhibits
strong negative residuals in the E-SE quadrant along with negative station anomaly, implying that it is underlain by an anomalous
high velocity crust/upper mantle. The negative residuals observed over India, continue beneath the Himalaya till the south
of Lhasa but change sign further northward, suggesting the northern limit of the Indian upper mantle structure. 相似文献
12.
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
13.
目前产生地震的机制仍以弹性回跳说为主:地震是因为断层错断使岩层的弹性能释放而引发。但越来越多的学者开始质疑,仅断层错断后的弹性能,是否真能达到实际地震所释放的巨大能量。因此,有必要探讨地震初动后破坏性强震的性质及其真正的能量来源。文章根据沉积地层中的储集层及其压力的特点分析得出,储集层内含有大量的高压流体,其压力在一定条件下可以释放出来,产生流体物理爆炸,有可能是强震能量的重要组成部分。通过计算得出,当断层破裂并刺穿面积较大的储集层时,其压力释放所产生的弹性能可以达到震级8.0以上地震所释放的能量;人为的工程活动也可引发小规模的流体压力的释放现象,如钻井时的井喷、水力压裂会诱发有感地震等。同时,文章根据对距离震中较近的地震台的波形及传播射线路径分析认为,强震波动可能不是横波S波,而是涨缩波P波,据此不能排除强震是由爆炸所致。综合汶川地震多个台站记录到的地震波的时间域和频率域特征、地面观测到的爆炸现象、地震后科学钻探获得的岩心等大量直接或间接证据,说明了这种流体爆炸能量释放的可能性。最后,文章提出了地震活动可分为三个阶段:微破裂阶段Ⅰ,该阶段有流体活动,并可产生动电效应,但未触发地震初动;地震初动后的断裂破裂阶段Ⅱ;由流体压力释放产生地震强震阶段Ⅲ。 相似文献
14.
The assessment of local site effects on seismic ground motions is of great importance in earthquake engineering practice.
Several destructive earthquakes in the past have demonstrated that the amplification of ground motion and associated damage
to structures due to local site conditions is a significant consideration in earthquake hazard analysis. A recent paper published
in this journal highlights the hazard posed by earthquakes in the megacity of Kolkata in India due to its seismic and geological
settings. The seismic hazard assessment study speculates that the deep alluvial deposit in the city may increase the seismic
hazard probably due to the amplification of the seismic energies. This paper focuses on the seismic response studies of the
various soil strata (i.e. for local subsurface conditions) obtained from various construction sites in the city for predicted
earthquake. It is very well recognized that site response studies (a part of seismic microhazard zonation for urban areas)
are the first step towards performance-based foundation design or seismic risk analysis and mitigation strategy. One of the
problems for carrying out site-specific study in Kolkata is the lack of recorded strong motion data in the city. Hence, this
paper outlines a methodology to carry out site-specific study, where no strong motion data or seismic data are available.
The methodology uses wavelet-based spectrum compatibility approach to generate synthetic earthquake motions and equivalent
linear method for seismic site response analysis. The Mega City of Kolkata has been considered to explain the methodology.
Seismic hazard zonation map by the Bureau of Indian Standards classifies the City of Kolkata as moderate seismic zone (Zone
III) with a zone factor 0.16. On the other hand, GSHAP(Global Seismic Hazard Assessment Program) map which is based on 10%
probability of exceedance in 50 years specifies a maximum peak ground acceleration (PGA) of 1.6 m/s2 (0.163 g) for this region. In the present study, the seismic response has been carried out based on GSHAP. The results of
the analysis indicate the amplification of ground motion in the range of 4.46–4.82 with the fundamental period ranging from
0.81 to 1.17 s. Furthermore, the maximum spectral accelerations vary in the range of 0.78–0.95 g. 相似文献
15.
S. T. G. Raghu Kanth 《Journal of Earth System Science》2008,117(2):683-705
Success of earthquake resistant design practices critically depends on how accurately the future ground motion can be determined at a desired site. But very limited recorded data are available about ground motion in India for engineers to rely upon. To identify the needs of engineers, under such circumstances, in estimating ground motion time histories, this article presents a detailed review of literature on modeling and synthesis of strong ground motion data. In particular, modeling of seismic sources and earth medium, analytical and empirical Green’s functions approaches for ground motion simulation, stochastic models for strong motion and ground motion relations are covered. These models can be used to generate realistic near-field and far-field ground motion in regions lacking strong motion data. Numerical examples are shown for illustration by taking Kutch earthquake-2001 as a case study. 相似文献
16.
湛江组结构性黏土区域微观结构特性研究 总被引：2，自引：0，他引：2
形成于早更新世的湛江组地层广泛分布于雷州半岛地区,其最为典型的灰色黏土因具有强结构性,在实际工程中出现了一系列岩土工程问题,为众多学者所关注。根据地层学研究结果,雷州半岛各区域的湛江组灰色黏土具有不同沉积环境。由于地质成因的差异,灰色黏土在不同区域表现出不同的工程特性。工程实际中,灰色黏土工程特性的区域性,使得工程界及研究者对于该土层的工程力学效益更是难以掌握。利用X射线衍射试验及电镜扫描试验,研究了不同区域灰色黏土的矿物成分及含量、微结构等微观结构特性。结果表明：不同沉积环境灰色黏土矿物成分及含量存在区域性差异,各矿物成分按照不同比例组合,形成的土体微结构区域特性明显。灰色黏土具有强结构性微观机制的揭示及区域差异性的分析,有利于对该层黏土的全面认知和利用。 相似文献
17.
A new fault-plane solution map of the Italian peninsula is presented in this paper. The earthquakes analyzed are included in the period 1905–1980, with magnitudes ranging 4–7, 75 earthquakes are located in the crust, while 31 are related to the deep and intermediate zone of the Calabrian arc. The large seismic events of the Italian peninsula are generally associated with normal faulting, while strike-slip motion is mostly related to small earthquakes, located along lateral segments of the mountain chain.The deep and intermediate earthquakes of the Tyrrhenian Sea indicate predominant down-dip compression, and strike-slip motion at the boundaries of this Benioff zone. This last is interpreted as a remnant of a subduction zone, active since Oligocene, extending to 500 km depth, with a very small lateral size (about 300 km). The present tectonics of this Benioff zone is strongly conditioned by the lateral bending, more so than the gravitational sinking process.The coexistence of thrust and normal faulting motion associated to the earthquakes, within a few tens of kilometers of each other, seems to be explained by the strong lateral inhomogeneities of the crustal rocks present in this region, more so than to the depth of the seismogenetic zone and the nature of the faulting process. 相似文献
18.
Natural Hazards - During 2006–2016, a strong motion seismic network of twenty 3-component accelerogarphs was deployed by the National Geophysical Research Institute, Hyderabad, India, in the... 相似文献
19.
华北地区距雄安新区300 km范围内包括唐山、邢台和张北三个典型强震区,近50年来,先后发生1966年邢台7.2级、1976年唐山7.8级和1998年张北6.2级强震活动,未来仍具发生破坏性地震的风险。在现今构造应力环境下,3个典型强震区内断裂活动危险性如何、再次发生中强地震对雄安新区地面稳定性有怎样的影响,这些都是要回答的问题。对此,本文首先基于唐山、邢台和张北强震区关键构造部位深孔水压致裂地应力测量数据,依据Byerlee断层滑动失稳摩擦准则,计算各强震区内潜在发震断层的临界失稳状态,探讨断裂活动危险性;之后依据中华人民共和国第五代《中国地震动参数区划图》之《中国大陆及邻区潜在震源区划分图》,厘定雄安新区外围300 km范围内主要潜在震源区和震级上限;最后选取适宜的地震烈度衰减模型,定量计算主要潜在震源区未来发生震级上限地震时对雄安新区地震烈度的影响,进而为雄安新区及重大工程抗震设防提供科学参考。结果表明：(1)唐山、邢台和张北强震区内主要潜在震源区未来发生震级上限地震产生的地震烈度衰减至雄安新区时均位于Ⅳ~Ⅶ度;(2)北京通州及邻区发生8.0级地震、涞水—高碑店沿线发生6.5级地震会在雄安新区产生Ⅶ度地震烈度,震害较轻;(3)其他潜在震源区在雄安新区产生的地震烈度均小于V度,并不会产生显著震害效应。鉴于此,雄安新区抗震设防烈度建议由原Ⅶ度调至Ⅷ度为宜。 相似文献
20.
二维分形技术在地震勘探构造解释中的应用 总被引：1，自引：0，他引：1
作者在文中探讨了二维分形布朗运动在地震勘探构造解释中的应用,并针对地震资料,提出了具体实用的算法,并以此算用Ｃ＾＋＋语言编制了相应处理软件,对实测地震资料进行了处理,取得了明显的效果。 相似文献