Full-scale experimental modal analysis of an arch dam: The first experience in Iran     

《Soil Dynamics and Earthquake Engineering》2014

Forced vibration field tests and finite-element studies were conducted on the Shahid Rajaee concrete arch dam in Northern Iran to determine the dynamic properties of the dam–reservoir–foundation system. The first forced vibration tests on the dam were performed with two different types of exciter units, with a limited maximum force, bolted on the dam crest for alternative in-phase and out-of-phase sequencing. Because of an insufficient number of recording sensors, two arrangements of sensors were used to cover sufficient points on the dam crest and one gallery during tests. Two kinds of vibration tests, on–off and frequency sweeping, were carried out on the dam. The primary natural frequencies of the coupled system for both symmetric and anti-symmetric vibration modes were approximated during on–off tests in two types of sequencing of exciters, in phase and out-of-phase, with a maximum frequency of 14 Hz. The principal forced vibration tests were performed at precise resonant frequencies based on the results of the on–off tests in which sweeping around the approximated frequencies at 0.1 Hz increments was performed. Baseline correction and suitable bandpass filtering were applied to the test records and then signal processing was carried out to compute the auto power, cross power and coherence spectra. Nine middle modes of vibration of the coupled system and corresponding damping ratios were estimated. The empirical results are compared against the results from calibrated finite-element modeling of the system using former ambient vibration tests, considering the dam–reservoir–foundation interaction effects. Good agreement is obtained between experimental and numerical results for eight middle modes of the dam–reservoir–foundation system.  相似文献   

高坝抗震设防问题的探讨   总被引：5，自引：1，他引：4  

贾超  金峰  王品江  张楚汉 《地震工程与工程振动》2005,25(1):155-158

本文探讨了高坝抗震设防的决策问题。分别从高坝设计使用年限及高坝的功能2个角度出发,探讨了进行高坝抗震设防标准决策的2种不同方法。从高坝设计使用年限出发,提出同样重要性的结构在不同的设计使用年限应具有相同的可靠度水平,以此来进行抗震设防烈度的决策。从基于功能分析的角度出发,提出应使总的期望损失最小为准则来进行最优抗震设防烈度的决策。  相似文献   

乌东德高拱坝极限抗震能力研究     

熊堃  翁永红  胡中平  曹去修 《岩土力学》2013,34(Z2):325-331

乌东德水电站是金沙江下游河段上4个水电梯级的最上游梯级,大坝为265 m高的双曲拱坝。采用非线性有限元法,将拱坝坝体-坝基作为一个整体系统,在考虑坝体横缝影响及无限地基辐射阻尼影响基础上,模拟坝肩控制性滑块各滑裂面在地震作用下张开、滑移的非线性力学行为,研究设计与校核地震作用下大坝的抗震性能,探讨大坝-坝基整体系统在强震作用下的抗震潜力。研究结果表明：设计地震条件下,坝体仅在拱端应力集中区域拉应力超过抗拉强度,压应力则均满足强度要求,坝肩块体稳定,大坝-坝基体系的整体安全性可以保证;校核地震条件下,坝体应力值略有增加,能够满足不溃坝的设防要求;以大坝-坝基代表性的位移、变形量变化曲线的拐点作为评价极限抗震能力的标准,可知拱坝-坝基体系的抗震超载安全系数为2.7,相应的基岩水平向峰值加速度0.729g,拱坝-坝基体系抗剪参数强度储备安全系数为2.0,乌东德高拱坝具备较强的极限抗震能力。  相似文献   

Nonlinear earthquake analysis of high arch dam–water–foundation rock systems     

Jin‐Ting Wang  Chu‐Han Zhang  Feng Jin 《地震工程与结构动力学》2012,41(7):1157-1176

A nonlinear finite element model for earthquake response analysis of arch dam–water–foundation rock systems is proposed in this paper. The model includes dynamic dam–water and dam–foundation rock interactions, the opening of contraction joints, the radiation damping of semi‐unbounded foundation rock, the compressibility of impounded water, and the upstream energy propagating along the semi‐unbounded reservoir. Meanwhile, a new equivalent force scheme is suggested to achieve free‐field input in the model. The effects of the earthquake input mechanism, joint opening, water compressibility, and radiation damping on the earthquake response of the Ertan arch dam (240 m high) in China are investigated using the proposed model. The results show that these factors significantly affect the earthquake response of the Ertan arch dam. Such factors should therefore be considered in the earthquake response analysis and earthquake safety evaluation of high arch dams. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Earthquake response of arch dams to spatially varying ground motion     

Anil K. Chopra  Jin‐Ting Wang 《地震工程与结构动力学》2010,39(8):887-906

The response of two arch dams to spatially varying ground motions recorded during earthquakes is computed by a recently developed linear analysis procedure, which includes dam–water–foundation rock interaction effects and recognizes the semi‐unbounded extent of the rock and impounded water domains. By comparing the computed and recorded responses, several issues that arise in analysis of arch dams are investigated. It is also demonstrated that spatial variations in ground motion, typically ignored in engineering practice, can have profound influence on the earthquake‐induced stresses in the dam. This influence obviously depends on the degree to which ground motion varies spatially along the dam–rock interface. Thus, for the same dam, this influence could differ from one earthquake to the next, depending on the epicenter location and the focal depth of the earthquake relative to the dam site. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

柱状节理坝基岩体三维各向异性数值分析   总被引：4，自引：1，他引：3  

徐卫亚  郑文棠  宁宇  孟国涛  吴关叶  石安池 《岩土力学》2010,31(3):949-955

在分析柱状节理不连续性和各向异性的工程特性基础上,对某拱坝及坝基的柱状节理岩体进行三维数值模拟分析。考虑河谷初始地应力场和岩体各向异性力学性质,采用各向同性本构和各向异性弹塑性本构进行对比分析。计算表明,坝基柱状节理岩体各向异性特性对工程整体应力、变形的影响比较明显,采用各向异性弹塑性模型计算更能反映柱状节理的特殊性。其结果为该坝区岩体工程各向异性力学分析提供了示例。  相似文献   

土石坝拟静力抗震稳定分析的强度折减有限元法   总被引：1，自引：1，他引：0  

李湛  栾茂田 《岩土力学》2010,31(5):1503-1508

基于拟静力抗震设计概念,提出利用强度折减有限单元法分析土石坝的抗震稳定性,给出了两种确定地震惯性力的方法：（1）依据《水工建筑物抗震设计规范》[1],并结合有关土石坝动态分布系数计算了沿坝高分布的地震惯性力;（2）直接利用土石坝有限元地震动力反应分析得到的单元节点加速度反应,依据建议的方法确定坝体各单元节点的地震惯性力。将上述计算确定的地震惯性力与其他形式的外荷载共同作用到土石坝上,采用强度折减有限元法确定土石坝坝体的拟静力抗震安全系数。对于稳定渗流期,水位降落期等不同工况,或需要考虑振动孔隙水压力作用的饱和无黏性土填筑坝等不同计算条件,给出了使用折减强度有限元法分析坝体抗震稳定性的实现途径和方法。研究表明,有限元法对边界条件、复杂断面条件和材料分区及荷载组合均具有较强的适应能力,因此,使用有限元法分析土石坝抗震稳定性具有显著的优越性。  相似文献   

某异型钢管混凝土拱桥地震反应分析     

李勇  闫维明  陈彦江 《震灾防御技术》2010,5(3):346-351

本文以某异型钢管混凝土拱桥为研究对象,通过ANSYS建立了结构的空间有限元模型,计算和分析了该桥的动力特性。同时,通过MATLAB程序生成拟合规范反应谱的人工地震波,并运用时程分析法计算了该桥在一维和多维输入下的地震反应,分析了该桥的地震反应规律,为钢管混凝土拱桥的抗震性能分析提供了一定的依据。  相似文献   

Transient analysis of concrete gravity dam-reservoir systems by Wavenumber-TD approach     

《Soil Dynamics and Earthquake Engineering》2016

The Wavenumber approach was initially introduced as an ideal substitute for the rigorous type of analysis which had been the basis of extensive studies in seismic analysis of concrete gravity dams. The former technique is formulated in the context of pure finite element programming, while the latter relies heavily on a two-dimensional semi-infinite fluid element (i.e., hyper-element). Recently, a variation of Wavenumber method was proposed which was referred to as Wavenumber-TD approach. The approximation to the original technique improves its realm of application and allows it to be carried out in time domain as well as frequency domain. In that study, the formulation was examined for harmonic type of excitation which proved to be promising. Herein, this will be evaluated for its real intended application, which is transient analysis of dam-reservoir systems. For this aim, the prepared special purpose finite element program is modified and the analysis of Pine Flat dam is considered as a typical example. Several models are considered with different values of normalized reservoir length. In each case, the reservoir truncation surface is treated by Wavenumber-TD and the extensively utilized Sommerfeld conditions. The dynamic loading considered is the S69E component of Taft earthquake record. Furthermore, two types of reservoir bottom condition of full reflective as well as absorptive, are adopted. Overall, this will allow for a thorough examination and evaluation of Wavenumber-TD approach in regard to its effectiveness.  相似文献   

钢管混凝土拱桥海上应用实例     

石彩亭 《中国勘察设计》2009,(9):38-40

近年来钢管混凝土拱桥建设在全国迅速发展,型式多样、各有千秋。本文就大跨度全钢系杆拱在大连新港50万吨级进口原油码头引桥上的成功应用做以下介绍。  相似文献