共查询到19条相似文献，搜索用时 703 毫秒
1.
2018年10月31日16时29分四川西昌发生M_S5.1地震,震中距官地大坝26 km,官地大坝强震监测台阵完整地记录到了本次地震过程。基于官地大坝强震监测台阵记录到的西昌地震强震动数据,通过分析各测点的时程特征、频谱反应规律,研究官地大坝在西昌地震作用下的反应特征和规律。研究表明大坝各部位PGA范围在3.70～69.98 gal,仪器烈度值在1.8～5.2度之间,受西昌地震破裂方向影响,强震动三分向峰值及频谱特性随着高程的增加呈明显的方向性放大效应,总体表现为顺河向分量大于横河向和垂直向分量;此次地震反应周期小于大坝基岩场地特征周期,且西昌地震激励下大坝场地卓越周期与大坝自振周期相差较大,本次地震对大坝安全无影响。 相似文献
2.
2008年古田4．1、4．6级地震强震动观测记录 总被引：2，自引：0，他引：2
水口水电站重力坝强震反应台阵在古田ML4．1、ML4．6地震中获得了强震资料,通过对观测资料初步分析,得到以下认识：如果仅用基岩自由场顺河向振动的峰值加速度进行估算．该大坝遭受的地震强度达到Ⅵ度。这与通过现场灾害评估得出大坝位于V度区外的结论相悖：坝底和基岩自由场竖直向和顺河向振动情况一致,但幅度存在差异;对于坝体的峰值加速度,相比较于坝底,坝中部三方向均有不同程度的放大,坝顶三方向均有不同程度的缩小：从坝底至坝顶。峰值加速度出现滞后现象,但并不明显,说明坝体刚性较大。此次地震中坝体主要呈整体振动特性。 相似文献
3.
混凝土大坝原型测量及抗震分析 总被引：2，自引：0，他引：2
以丹江口大坝、葛洲坝闸墩坝、新丰江大坝和潭岭大坝强震观测为例，介绍了混凝土大坝原型观测中所使用的仪器、测量方法（强震观测和微振观测）及获取的初步成果，扼要介绍了混凝土大坝抗震分析的内容（包括结构动力特性分析、坝体稳定性分析和强度验算）和方法（拟静力法和反应谱法），最后，详细介绍了利用强震记录对新丰江大坝和潭岭大坝进行抗震分析的结果，并由此看出强震观测对于大坝抗震的重要性。 相似文献
4.
通过对水口水电站重力坝强震反应台站在古田地震中获取的强震反应观测资料进行信噪比、反应谱和功率谱分析,得到如下结论:①大坝在0.7～15 Hz频率段的振动特性较为可信;②坝基和自由场输入地震动富于高频,峰值加速度反应谱存在较大差异;③坝基输入地震动存在差异性,建议今后此类大坝抗震设计时考虑多点地震动输入;④单个卓越频率携带的能量对反应谱影响不大,反应谱是和输入地震动总能量相关的;⑤坝体刚度较大,此次地震中还处于线弹性状态。初步了解了强震记录的地震动特性和大坝结构的抗震性能,对认识水库地震近场地震动特性和重力坝地震反应有一定的参考意义。 相似文献
5.
6.
《国际地震动态》2020,(7)
建筑结构地震反应观测是获取不同建筑结构在地震中的反应状态与特征的有效手段。河北省唐山古冶5.1级地震触发北京地区既有的建筑结构观测台阵,获得了丰富的建筑结构地震反应记录。开展台阵记录的初步分析,确定结构动力放大倍数和仪器烈度分布。分析发现,不同类型结构的动力放大倍数差异较大,钢结构较砌体结构的动力放大倍数更大。震中距较小的台阵的仪器烈度较大,最大达到2.5度。以第十九中学教学楼为例,开展单个观测台阵的地震记录分析,得到结构各楼层的水平向加速度分布,互功率谱分析得到结构振动的卓越频率。初步分析表明,基于观测记录数据分析能得到地震动特性和建筑结构动力特性参数,为了解区域建筑结构特性奠定有效数据基础。 相似文献
7.
《地震工程与工程振动》2017,(2)
大坝的强震观测是传感器测量的结构在地震激励下实际的振动反应。基于强震观测进行混凝土拱坝模态参数识别,可为结构的抗震分析、健康诊断和震损评估等提供基础。本文基于Pacoima拱坝的3次地震观测数据,分别采用"输入-输出"型和"仅考虑输出"型两类方法对大坝的模态参数进行了识别,并对不同地震记录下,不同方法的识别结果进行对比。同时,结合国内外不同学者通过数值计算、大坝原型动力试验和运行模态分析等方式得到的Pacoima拱坝模态参数识别的结果,分析了基于强震观测的模态识别结果与上述方式获得的模态参数的差异,并分析了差异产生的原因。相关的研究成果,可为后续的研究提供参考。 相似文献
8.
9.
对上海佘山地震台在汶川地震中测得的基岩波地震记录进行频谱特性分析,然后以同济大学教学科研综合楼场地土层为研究对象,应用水平成层土层地震反应的一维有限元方法,分析该深覆盖场地在这一实测地震记录作用下的动力反应,并将其与同济大学强震监测台在汶川地震中获得的地表波记录进行对比。结果表明：汶川地震的远场地震动记录中,基岩波的长周期卓越性比地表波更为明显;而在土层剪应变为10-6~10-4的小变形阶段,《上海市地震动参数区划》中给出的各类土壤的阻尼比建议值明显偏小。最后,对阻尼比的修正进行了一些探讨。 相似文献
10.
11.
Numerical investigation of the response of the Yele rockfill dam during the 2008 Wenchuan earthquake
In this paper the seismic response of a well-documented Chinese rockfill dam, Yele dam, is simulated and investigated employing the dynamic hydro-mechanically (HM) coupled finite element (FE) method. The objective of the study is to firstly validate the numerical model for static and dynamic analyses of rockfill dams against the unique monitoring data on the Yele dam recorded before and during the Wenchuan earthquake. The initial stress state of the dynamic analysis is reproduced by simulating the geological history of the dam foundation, the dam construction and the reservoir impounding. Subsequently, the predicted seismic response of the Yele dam is analysed, in terms of the deformed shape, crest settlements and acceleration distribution pattern, in order to understand its seismic behaviour, assess its seismic safety and provide indication for the application of any potential reinforcement measures. The results show that the predicted seismic deformation of the Yele dam is in agreement with field observations that suggested that the dam operated safely during the Wenchuan earthquake. Finally, parametric studies are conducted to explore the impact of two factors on the seismic response of rockfill dams, i.e. the permeability of materials comprising the dam body and the vertical ground motion. 相似文献
12.
紫坪铺水库蓄水前天然地震活动 总被引：8，自引：0，他引：8
紫坪铺水库位于龙门山断裂带。了解和掌握水库蓄水前库坝区及其周围天然地震活动背景水平,可对水库诱发地震的危险性进行前期评价,可为蓄水后的诱发地震活动监测提供可靠的鉴别依据。紫坪铺水库地震台网在水库蓄水前运行逾1年,本文用这批资料提供表征库区及附近和库坝区蓄水前天然地震活动水平确切实用的各项指标。用全国和四川台网地震资料,给出含库区的较大区域地震活动背景和对库区的影响。 相似文献
13.
G. Gudehus R. O. Cudmani A. B. Libreros-Bertini M. M. Bühler 《Soil Dynamics and Earthquake Engineering》2004,24(4):319-342
The concept of in-plane and anti-plane shaking is introduced with a rigid block on a plane surface with Coulomb friction. Using a hypoplastic constitutive relation to model the mechanical behaviour of the soil, numerical solutions for a rigid block on a thin dry or saturated soil layer are obtained. The coupled nature of dynamic problems involving granular materials is shown, i.e. the motion of the block changes the soil state—skeleton stresses and density—which in turn affects the block motion. Motions of the block as well as soil response can be more realistically calculated by the new model. The same constitutive equation is applied to the numerical simulation of the propagation of plane waves in homogeneous and layered level soil deposits induced by a wave coming from below. Experiments with a novel laminar shake box as well as real seismic records from well-documented sites during strong earthquakes are used to verify the adequacy of the hypoplasticity-based numerical model for the prediction of soil response during strong earthquakes. The response of a homogeneous earth dam subjected to in-plane and anti-plane shaking is investigated numerically. In-plane and anti-plane shaking is shown to cause nearly the same spreading of a sand dam under drained conditions, whereas under undrained conditions anti-plane shaking causes stronger spreading of the dam. The dynamic behaviour of a breakwater founded on rockfill and soft clay during the 1995 Kobe earthquake is back-calculated to show the good performance of the proposed numerical model also with a structure. Section 9 deals with buildings on mattresses of densified cohesionless soils or fine-grained soils with granular columns, slopes with ‘hidden’ dams and structures on piles traversing clayey slopes to show the suitability of hypoplasticity-based models for the earthquake-resistant design and safety assessment of geotechnical systems. 相似文献
14.
15.
The joint between concrete slab and rockfill is designed as welded contact in the classical modeling of concrete-faced rockfill (CFR) dams and earthquake response of the CFR dams is determined by this method. In this study, linear and nonlinear response of Torul CFR Dam including interface element between concrete slab and rockfill were investigated for the duration of strong seismic excitation. The finite element analyses were performed by employing both cases, empty and full reservoir, to research the effect of the reservoir water on the earthquake response of the dam. The reservoir water was modeled with fluid finite elements by the Lagrangian approach. The Drucker-Prager model was used in nonlinear analyses for concrete slab, rockfill and soil materials. According to finite element analyses, displacement and stress components were increased by hydrodynamic pressure. The nonlinear response of the concrete slab was monitored about the peak ground acceleration (pga). This study reveals that the size of sliding zone increases with increasing acceleration amplitudes. 相似文献
16.
Rockfill buttressing resting on the downstream face of masonry or concrete gravity dam is often considered as a strengthening method to improve the stability of existing dam for hydrostatic and seismic loads. Simplified methods for seismic stability analysis of composite concrete-rockfill dams are discussed. Numerical analyses are performed using a nonlinear rockfill model and nonlinear dam-rockfill interface behavior to investigate the effects of backfill on dynamic response of composite dams. A typical 35 m concrete gravity dam, strengthened by rockfill buttressing is considered. The results of analyses confirm that backfill can improve the seismic stability of gravity dams by exerting pressure on the dam in opposition to hydrostatic loads. According to numerical analyses results, the backfill pressures vary during earthquake base excitations and the inertia forces of the backfill are the main source for those variations. It is also shown that significant passive (or active) pressure cannot develop in composite dams with a finite backfill width. A simplified model is also proposed for dynamic analysis of composite dam by replacing the backfill with by a series of vertical cantilever shear beams connected to each other and to the dam by flexible links. 相似文献
17.
2020年1月19日和2020年2月21日在新疆喀什地区先后发生MS6.4和MS5.1地震,针对新疆强震动台网收集到的128条强震动记录进行统计分析,研究2次地震记录的幅值及反应谱特性,并与两个现行规范设计反应谱进行对比,结果表明：(1)震级相同时,震中距越小加速度反应谱越大,且加速度反应谱衰减速度越慢;震中距相同时,震级越大加速度反应谱越大,且加速度反应谱衰减速度越慢;(2)震级越大加速度谱值、速度谱值、位移谱值越大;(3)MS6.4、MS5.1地震波加速度反应谱及其平均值曲线相近,与我国现行规范加速度反应谱相比差别很大。建议在新疆喀什地区采用基于当地强震记录的加速度反应谱进行结构抗震设计。 相似文献
18.
A number of questions concerning the response of concrete gravity dams to earthquakes, motivated by the structural damage caused to Koyna Dam, which has an unconventional cross section, by the December 1967 Koyna earthquake, are considered in this work. The study is not restricted to the earthquake experience at Koyna Dam, but includes consideration of a dam with a typical section and another earthquake motion having similar intensity but different peak acceleration and frequency characteristics compared to the Koyna ground motion. The earthquake response in a number of cases is analysed by the finite element method and results are presented. These results lead to a number of conclusions. Significant tensile stresses must have developed in Koyna Dam during the Koyna earthquake and similar stresses would have developed even in typical gravity dam sections. The Koyna ground motion is relatively more severe, compared to California earthquakes of similar intensity, on concrete gravity dams. The extra concrete mass near the crest of a gravity dam to support the roadway, etc. is responsible for causing a significant part of the critical tensile stresses; attention should therefore be given to developing lightweight supporting systems. 相似文献
19.
Geological, geophysical and seismological criteria for local response evaluation in Bucharest urban area 总被引：4，自引：0，他引：4
N. Mndrescu M. Radulian Gh. M&#x;rmureanu 《Soil Dynamics and Earthquake Engineering》2007,27(4):367-393
Vrancea major intermediate-depth earthquakes produced extreme damage in Bucharest city, located at about 165 km epicenter distance. Our purpose is to investigate the influence of local geological conditions upon the seismic motion in Bucharest in case of large (M>7) Vrancea earthquakes. Two input data sets are used: (a) geological, geotechnical and geophysical information, including in situ measurements, and (b) acceleration recordings of Vrancea earthquakes. Local response evaluation based on first dataset is confirmed by the spectral analysis of the earthquake records. Two main features are outlined: non-stationarity of ground motion dynamic amplification from one event to other and inadequacy of limiting the investigation depth to uppermost 30 m to evaluate ground dynamic characteristics. Consequently (1) we cannot extrapolate the ground motion response determined for moderate and small earthquakes to anticipate the effects of the large Vrancea shocks and (2) the local response is controlled by the entire package of Quaternary deposits which are significantly deeper than 30 m depth beneath Bucharest Area. 相似文献