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1.
Estimation of Nonlinear Time-dependent Soil Behavior in Strong Ground Motion Based on Vertical Array Data 总被引：2，自引：0，他引：2
To improve our understanding of nonlinear elastic properties of soils, a method is proposed of estimation of stress-strain relations of soils in situ in strong ground motion based on vertical array data. Strong motion records provided by seismic vertical arrays allow estimation of nonlinear stress-strain relations in soil layers at different depths, from the surface down to the location of the deepest device. As an example, records obtained during the main shock of the 1995 Kobe earthquake at Port-Island, SGK, and TKS sites were used to estimate the stress-strain relations in the soil profiles. For different layers, different types of nonlinear stress-strain relations were selected, according to the profiling data. To account for temporal changes in the soil behavior, consecutive parts of records were examined, and for successive time intervals, the relations were found showing the best-fit approximation to the observed data. At Port Island and SGK sites, where the strongest accelerations were recorded, the obtained stress-strain relations showed systematic changes in the upper layers (0–14 m), such as, a progressive reduction of the slopes of the stress-strain curves due to liquefaction at Port Island and reduction and recovery of the slopes at SGK and TKS sites. At the three sites, the stress-strain relations remained stable in layers below 11–14 m. Thus, the proposed approach gives us a representation of the soil behavior in layers at different depths in strong ground motion; it allows calculation of the propagation of arbitrary seismic signals in the studied profiles and estimation of nonlinear components in the ground response by the nonlinear system identification technique. The method can also be applied to evaluate the ground response at sites where profiling data are available and an imposed motion can be estimated. 相似文献
2.
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
3.
Simultaneous identification of time and space variant dynamic soil properties during the 1995 Hyogoken-Nanbu earthquake 总被引：2，自引：0，他引：2
Time and space variant soil properties at a liquefied site were simultaneously identified in the time domain by using borehole array strong motion records. During soil liquefaction at a site, soils usually show a wide variety of non-linear behavior along the depth as well as non-stationary behavior. Strong ground motion records were obtained at Port Island borehole array observatory, Kobe, during the 1995 Hyogoken-Nanbu earthquake. In this study, the instrumented soil was modeled by the equivalent linear MDOF system, and an extended Kalman filter with local iteration was employed for the identification of the soils. The identification process was successfully conducted, and the stress–strain relationships of the soils at the liquefied site were obtained from different depths all at once. 相似文献
4.
为了研究速度脉冲型地震动的最强速度脉冲方向分量与垂直或平行断层方向分量之间的特性差异,本文采用多分量速度脉冲识别方法从NGA-West2强震动数据库的236组近断层地震动速度脉冲记录中提取出最强速度脉冲方向分量,对其脉冲参数随震级MW和断层距R变化的统计关系式进行了回归分析,并对比了最强速度脉冲方向分量与垂直或平行断层方向分量之间的特性差异。研究结果表明:当R＜30 km时,最强速度脉冲方向分量的脉冲幅值预测值较垂直或平行断层方向分量的预测值大,而当R＞30 km时,两种分量的脉冲幅值预测值相差不大,可以忽略;当MW≤7.5时,最强速度脉冲方向分量的脉冲周期预测值比垂直或平行断层方向分量的预测值大,而当MW＞7.5时,两种分量的脉冲周期预测值差异不大,可以忽略。 相似文献
5.
Characteristics of Soil Response in Near-Fault Zones During the 1999 Chi-Chi, Taiwan, Earthquake 总被引：1，自引：0，他引：1
O. V. Pavlenko 《Pure and Applied Geophysics》2008,165(9-10):1789-1812
Distribution of parameters characterizing soil response during the 1999 Chi-Chi, Taiwan, earthquake (M w = 7.6) around the fault plane is studied. The results of stochastic finite-fault simulations performed in Pavlenko and Wen (2008) and constructed models of soil behavior at 31 soil sites were used for the estimation of amplification of seismic waves in soil layers, average stresses, strains, and shear moduli reduction in the upper 30 m of soil, as well as nonlinear components of soil response during the Chi-Chi earthquake. Amplification factors were found to increase with increasing distance from the fault (or, with decreasing the level of “input” motion to soil layers), whereas average stresses and strains, shear moduli reduction, and nonlinear components of soil response decrease with distance as ~ r ?1 . The area of strong nonlinearity, where soil behavior is substantially nonlinear (the content of nonlinear components in soil response is more than ~40–50% of the intensity of the response), and spectra of oscillations on the surface take the smoothed form close to E(f) ~ f ?n , is located within ~20–25 km from the fault plane (~ 1/4 of its length). Nonlinearity decreases with increasing distance from the fault, and at ~40–50 km from the fault (~ 1/2 of the fault length), soil response becomes virtually linear. Comparing soil behavior in near-fault zones during the 1999 Chi-Chi, the 1995 Kobe (M w = 6.8), and the 2000 Tottori (Japan) (M w = 6.7) earthquakes, we found similarity in the behavior of similar soils and predominance of the hard type of soil behavior. Resonant phenomena in upper soil layers were observed at many studied sites; however, during the Chi-Chi earthquake they involved deeper layers (down to ~ 40–60 m) than during lesser-magnitude Kobe and Tottori earthquakes. 相似文献
6.
Records of the 1999 Chi–Chi earthquake, provided by the Dahan downhole array were analyzed, and nonlinear hysteretic stress–strain relations in the soil layers were estimated by the method previously used for studying the response of soils during the 1995 Kobe and the 2000 Tottori earthquakes. The obtained models of the soil behavior were applied for evaluating changes of the shear moduli in the soil layers and for the nonlinear identification of the soil behavior at Dahan site during the Chi–Chi earthquake. We found that reduction of the shear moduli in the soil layers did not exceed 5%, and the soil response was virtually linear. The content of the nonlinear components in the soil response was about 5% of the intensity of the response, and it was mostly due to the odd-order nonlinearities. A similarity in the stress–strain relations describing the behavior of soils during the 1995 Kobe earthquake, the 2000 Tottori earthquake, and the 1999 Chi–Chi earthquake was found, which indicates the possibility to describe the behavior of similar types of soils at different sites by similar stress–strain relations and predict soil behavior in future earthquakes. 相似文献
7.
Amplification of earthquake-induced seismic waves by soft superficial deposits often causes significant damages in the urban areas. In predicting this effect for large future earthquakes, the linear elastic response of soils is customarily assumed. To check this assumption, we have analyzed surface and downhole acceleration data from the SMART1 and SMART2 strong motion arrays in Taiwan, covering peak accelerations of up to 0·3 g. First, frequency-dependent amplification induced by the alluvial deposits at the SMART1 array was estimated using spectral ratio technique, where the records at rock site were taken as a reference motion. Statistically validated reduction in soil amplification in the strong motion relative to the weak motion in the frequency range between approximately 1 and 9 Hz was detected. Secondly, relative site responses between the Pleistocene and recent sedimentary deposits at the SMART2 array were studied. Relative amplification was shown to be clearly dependent on the excitation level. Thirdly, we compared experimentally recorded uphole/downhole spectral ratios on weak and strong ground motion with the theoretical response yielded by the geotechnical code DESRA2 which assumes hysteretic constitutive relationship of soil. Major symptoms of nonlinear ground behavior predicted by the model were found in the observed data. Back-calculation of the shear wave velocities to the depth of 47 m shows nearly 50% decrease in the strongest quakes, also accounted for by the nonlinear soil behavior. 相似文献
8.
W.R. Stephenson Cinna Lomnitz Hortencia Flores 《Soil Dynamics and Earthquake Engineering》2006,26(8):791-798
Recordings of the ground motion induced by two shallow (15–25 km deep), distant (300 and 605 km) earthquakes made on deep, soft lacustrine sediments at Texcoco, Valley of Mexico, show a late monochromatic response at 0.48 Hz. Data from a strong-motion recorder array show that this late response is consistent with slow (60 m/s group velocity) Rayleigh waves generated near the 6 km distant soft/stiff soil interface of the ex-lake surface margin. It is concluded that the excitation of local Rayleigh waves in soft soil deposits by arriving earthquake ground motion provides one mechanism to explain the prolonged duration of resonant motion on soft soils, and hence the extreme damage often associated with soft soils responding to distant earthquakes. 相似文献
9.
The 1999 Chi-Chi, Taiwan, earthquake (Mw = 7.6) was one of the strongest earthquakes in recent years recorded by a large number of strong-motion devices. Though only
surface records are available, the obtained strong-motion database indicates the variety of ground responses in the near-fault
zones. In this study, accelerograms of the Chi-Chi earthquake were simulated at rock and soil sites, and models of soil behavior
were constructed at seven soil sites (TCU065, TCU072, TCU138, CHY026, CHY104, CHY074, and CHY015), for which parameters of
the soil profiles are known down to depths of at least ~70 m and at 24 other soil sites, for which parameters of the soil
profiles are known down to 30–40 m; all the sites were located within ~50 km from the fault. For reconstructing stresses and
strains in the soil layers, we used a method similar to that developed for the estimation of soil behavior based on vertical
array records. As input for the soil layers, acceleration time histories simulated by stochastic finite-fault modelling with
a prescribed slip distribution over the fault plane were taken. In spite of the largeness of the earthquake’s magnitude and
the proximity of the studied soil sites to the fault plane, the soil behavior at these sites was relatively simple, i.e.,
a fairly good agreement between the spectra of the observed and simulated accelerograms and between their waveforms was obtained
even in cases where a single stress-strain relation was used to describe the behavior of whole soil thickness down to ~70–80
m during strong motion. Obviously, this is due to homogeneity in the characteristics of soil layers in depth. At all the studied
sites, resonant phenomena in soil layers (down to ~40–60 m) and nonlinearity of soil response were the main factors defining
soil behavior. At TCU065, TCU110, TCU115, CHY101, CHY036, and CHY039 liquefaction phenomena occurred in the upper soil layers,
estimated strains achieved ~0.6–0.8%; at other stations, maximum strains in the soil layers were as high as 0.1–0.4%, according
to our estimates. Thus, valuable data on the in situ soil behavior during the Chi-Chi earthquake was obtained. Similarity in the behavior of similar soils during the 1995 Kobe,
2000 Tottori (Japan), and Chi-Chi (Taiwan) earthquakes was found, indicating the possibility of forecasting soil behavior
in future earthquakes. In the near-fault zones of the three earthquakes, “hard-type” soil behavior and resonant phenomena
in the upper surface layers prevail, both leading to high acceleration amplitudes on the surface. 相似文献
10.
Records of the Niigata Chuetsu-Oki earthquake (July, 16, 2007, M w?=?6.6, depth ~17?km) and its aftershocks from seismic vertical arrays deployed at the territory of the Kashiwazaki-Kariwa nuclear power plant (~15?km from the fault) are used to study the soil behavior down to ~250?m during strong ground motion. Nonlinear models of soil behavior during the main shock and six aftershocks are constructed, and stresses and strains induced by the strong motion in the soil layers at various depths are estimated. The data are processed using the method developed by Pavlenko and Irikura (Bull Seismol Soc Am 96(6): 2131–2145, 2003) and previously applied for studying the soil behavior in near-fault zones during the 1995 Kobe and 2000 Tottori earthquakes. A rather good agreement between the recorded and simulated acceleration time histories testifies to the validity of the obtained vertical distributions of stresses and strains in soil layers. In the upper, softer layers (~45?m) at the territory of the plant, the shear moduli were reduced by ~30–35% during the main shock and by ~1.5–3% during the aftershocks. The constructed models of soil behavior can be used in scenario earthquake shaking maps of Japan where, based on source modeling parameters, the level of strong motion can be evaluated for the territory of the power plant in future earthquakes with various magnitudes and fault planes. Using methods of stochastic finite-fault modeling of ground motions from the Chuetsu-Oki earthquake, we estimated input motion to the soil layers during the main shock and found that it differs from the imposed motion (recorded by the deepest sensor of the vertical array) by slightly decreased (by a factor of ~1.2) low-frequency (f?<?10?Hz) spectral components. 相似文献
11.
O. V. Pavlenko 《Pure and Applied Geophysics》2013,170(4):571-595
To estimate the parameters of ground motion in future strong earthquakes, characteristics of radiation and propagation of seismic waves in the Kamchatka region were studied. Regional parameters of radiation and propagation of seismic waves were estimated by comparing simulations of earthquake records with data recorded by stations of the Kamchatka Strong Motion Network. Acceleration time histories of strong earthquakes (M w = 6.8–7.5, depths 45–55 km) that occurred near the eastern coast of Kamchatka in 1992–1993 were simulated at rock and soil stations located at epicentral distances of 67–195 km. In these calculations, the source spectra and the estimates of frequency-dependent attenuation and geometrical spreading obtained earlier for Kamchatka were used. The local seismic-wave amplification was estimated based on shallow geophysical site investigations and deep crustal seismic explorations, and parameters defining the shapes of the waveforms, the duration, etc. were selected, showing the best-fit to the observations. The estimated parameters of radiation and propagation of seismic waves describe all the studied earthquakes well. Based on the waveforms of the acceleration time histories, models of slip distribution over the fault planes were constructed for the studied earthquakes. Station PET can be considered as a reference rock station having the minimum site effects. The intensity of ground motion at the other studied stations was higher than at PET due to the soil response or other effects, primarily topographic ones. At soil stations INS, AER, and DCH the parameters of soil profiles (homogeneous pyroclastic deposits) were estimated, and nonlinear models of their behavior in the strong motion were constructed. The obtained parameters of radiation and propagation of seismic waves and models of soil behavior can be used for forecasting ground motion in future strong earthquakes in Kamchatka. 相似文献
12.
O. V. Pavlenko 《Izvestiya Physics of the Solid Earth》2006,42(1):69-78
Records of the Chi-Chi (Taiwan) earthquake of 1999 (M w = 7.7) obtained at the Dahan vertical array (a part of the SMART-2 array) in NE Taiwan are analyzed. The Dahan array was located at a distance of ～80 km from the fault plane of the earthquake. Using the method previously applied to the analysis of soil behavior during the Japan earthquakes in Kobe (1995) and Tottori (2000), nonlinear stress-strain relations are estimated in soil layers at depths of 0–200 m at the Dahan site for successive time intervals. The resulting soil behavior model is used for estimating variations in shear moduli and for the identification of nonlinear behavior of soil layers during an earthquake. According to the model estimates, the earthquake-related decrease in shear moduli did not exceed ～5% and the soil response was nearly linear (the amount of its nonlinear components was also no more than ～5%). The stress-strain relations describing the soil responses to the earthquakes in Kobe (1995), Tottori (2000), and Chi-Chi (1999) are similar, implying that, in principle, it is possible to describe the behavior of soils of the same type by the same stress-strain relations and predict the soil response to a future earthquake. 相似文献
13.
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
14.
Vladimir Sokolov Chin-Hsiung Loh Kuo-Liang Wen 《Soil Dynamics and Earthquake Engineering》2002,22(9-12):781-790
In the Taiwan region, the empirical spectral models for estimating ground motion parameters were obtained recently on the basis of recordings of small to moderate (5.0≤ML≤6.5) earthquakes. A large collection of acceleration records from the recent ML 7.3 (MW 7.6) Chi-Chi earthquake (20 September, 1999) makes it possible to test the applicability of the established relationships in the case of larger events. The comparison of ground motion parameters (peak accelerations and response spectra), which were calculated using the stochastic approach based on the modeled Fourier amplitude spectra, and the observed data demonstrates that the models may be successfully used for ground motion prediction for earthquakes of magnitudes up to ML=6.8–7.0 and hypocentral depth more than 10 km. To satisfy to the peculiarities of ground motion during shallow (depth less than 10 km) and larger (ML>7.0) events, the models were revised. 相似文献
15.
选取分布在北川-映秀中央断裂两侧断层距120 km以内的40个强震动台站的记录,对汶川地震近断层地震动竖向和水平向加速度峰值、速度峰值、竖向和水平向加速度反应谱及谱比值进行了统计分析.研究表明:(1)地震动加速度峰值有显著的上盘效应,经验衰减模型的结果表明,在距地表破裂3~60 km的范围内,龙门山发震断层上盘一侧竖向与水平向的加速度峰值要比衰减模型得到的平均值大30%~40%.上盘的加速度峰值残差大部分是正值,而断层下盘残差大部分为负;水平地震动的东西分量幅值总体要大于南北分量,东西分量衰减相对较慢.(2)地震动长周期成分较弱,加速度反应谱值随周期增大而迅速减小,在周期1.0 s 时,即使在靠近中央断裂的最大加速度反应谱值也只有0.5 g;地震动加速度反应谱谱比值(竖向/水平向)沿龙门山断层周围的分布,在较长周期(T=0.2 s, 0.5 s, 1.0 s)与短周期(T=0.05 s, 0.1 s)有明显的不同.(3)近断层竖向地震动显著,地震动加速度峰值比在(竖向/水平向)可达1.4.在龙门山发震断层的上盘,地震动加速度峰值比整体上比下盘要大,竖向地震动尤为剧烈.部分近断层记录的地震动谱比值(竖向/水平向)在短周期(< 0.1 s)甚至超过1.5,统计分析还表明谱比值在短周期段(< 0.1 s)随断层距的增大而减小. 相似文献
16.
2013年4月20日的芦山7.0级地震是继2008年5月12日汶川8.0级特大地震之后,发生在龙门山断裂带上的又一次大震级逆冲型地震.与汶川地震相比,芦山地震的发震断层没有地表出露,断层的滑动角更大,其逆冲性质更强烈.本文挑选了芦山地震中断层距小于200km的45条强震动记录,基于地震动衰减关系进行统计分析,对比了上盘和下盘台站地震动参数相对于衰减关系的对数残差.结果表明：芦山地震的上下盘效应明显,近断层上盘地震动的高频成分要高于同断层距的下盘;上盘地震动衰减要明显快于下盘.地震动衰减关系用简单的一个距离参数很难描述近场断层尺寸效应的影响,也很难模拟地震动上下盘效应.因此,在近场强地面运动模拟中,应多考虑有限断层模型,以模拟断层的尺寸效应. 相似文献
17.
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
18.
选取了1999年9月21日台湾集集7.6级地震主震中68组断层距在20km以内的近断层台站记录和46组断层距在40~70km的东部台站记录,按台站的上下盘位置、场地条件和断层距分组,对其竖向和水平加速度反应谱比值V/H进行了统计分析。研究表明:1)断层的滑动方向和断层破裂的传播方向对断层距在3km以内的台站上的地面运动谱比值V/H有一定影响,且主要体现在中短周期范围内,例如平行断层方向的谱比值要比垂直断层方向的谱比值大。在下盘断层距3~20km的范围内,场地条件对V/H基本没有影响。2)在集集地震中长周期(>3s)部分的谱比值通常>32,且有一个较高的峰值,表明其竖向运动加速度中的长周期分量大于其它地震。3)对于下盘的台站,地面运动在短周期(<0.2s)段的谱比值不随断层距的增加而减少。与中远(>40km)距离的台站相比较,近断层台站的V/H在工程界关心的周期范围内普遍较大。4)场地条件对谱比值V/H的影响在近断层处不显著。在远离断层的东部台站上,硬土场地谱比值V/H在长周期段大于软土场地 相似文献
19.
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
20.
2012年5月28日河北省唐山市古冶区与滦县交界发生4.8级地震, 国家强震动台网中心在河北、 天津和北京的94个强震动台站记录到了本次地震的加速度。 本文给出了获取记录的强震动台站分布及强震动记录结果, 统计了强震动记录数量随震中距的变化, 给出了3个较小震中距台站记录到的加速度时程; 绘制了空间地震动峰值加速度等值线图及周期0.2 s、 2.0 s加速度反应谱值的等值线, 发现峰值加速度等值线与长周期加速度反应谱等值线极值分布具有明显地域差异, 分析认为是由于厚沉积层对长周期地震动具有放大作用造成的。 通过强震动记录与适用于本区的三个衰减关系对比, 分析了此次地震的峰值加速度衰减特征, 同时研究了周期0.2 s、 2.0 s加速度反应谱值的衰减特征, 周期2.0 s反应谱值随震中距的衰减与衰减关系能较好地对应, 然而在震中距100～130 km沉积层较厚的集中地区, 表现出了实际记录较衰减关系值偏大的现象, 认为同样是由于厚沉积层对地震动加速度反应谱长周期的放大作用导致的。 研究了震中距差别不大的情况下, 场地类型与沉积层厚度对反应谱特征周期的影响, 对比基岩台站与软弱地基土层台站的强震动记录反应谱, 发现软弱土层台站的土层对地震动有一定的放大作用, 导致中长周期地震动被放大, 对比位于沉积层较薄的隆起区台站与位于沉积层较厚的凹陷区台站强震动记录反应谱, 发现厚的沉积层不仅对反应谱长周期有放大的作用, 同时也会使得反应谱特征周期值变大。 相似文献