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1.
Shaking table test on the seismic failure characteristics of a subway station structure on liquefiable ground 总被引：1，自引：0，他引：1
In order to investigate the seismic failure characteristics of a structure on the liquefiable ground, a series of shaking table tests were conducted based on a plaster model of a three‐story and three‐span subway station. The dynamic responses of the structure and ground soil under main shock and aftershock ground motions were studied. The sand boils and waterspouts phenomena, ground surface cracks, and earthquake‐induced ground surface settlements were observed in the testing. For the structure, the upward movement, local damage and member cracking were obtained. Under the main shock, there appeared longer liquefaction duration for the ground soil while the pore pressure dissipated slowly. The acceleration amplification effect of the liquefied soil was weakened, and the soil showed a remarkable shock absorption and concentration effect with low frequency component of ground motion. However, under the aftershock, the dissipation of pore pressure in the ground soil became obvious. The peak acceleration of the structure reduced with the buried depth. Dynamic soil pressure on the side wall was smaller in the middle and larger at both ends. The interior column of the model structure was the weakest member. The peak strain and damage degree for both sides of the interior column exhibited an ‘S’ type distribution along the height. Moreover, the seismic response of both ground soil and subway station structure exhibited a remarkable spatial effect. The seismic damage development process and failure mechanism of the structure illustrated in this study can provide references for the engineers and researcher. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
2.
强地震动作用下地铁结构与土脱开滑移的研究 总被引：4，自引：0，他引：4
刘如山 《地震工程与工程振动》2004,24(6):136-141
应用反应位移法,有限元反应位移法和有限元动力分析方法,以兵库县南部地震的Port-Island观测波形作为地震动输入,对某给定地质条件下的浅埋箱型地铁结构进行了不考虑结构与土脱开滑移和考虑结构与土脱开滑移的两种情况的计算,通过计算可以了解到一般箱型结构与上脱开,滑移的位置和范围,计算结果表明,抗震设计时,在强地震作用下,结构与土的脱开,滑移作用考虑与否,对结构变形和断面力计算值的影响很大。 相似文献
3.
This paper presents a new way of selecting real input ground motions for seismic design and analysis of structures based on a comprehensive method for estimating the damage potential of ground motions, which takes into consideration of various ground motion parameters and structural seismic damage criteria in terms of strength, deformation, hysteretic energy and dual damage of Park & Ang damage index. The proposed comprehensive method fully involves the effects of the intensity, frequency content and duration of ground motions and the dynamic characteristics of structures. Then, the concept of the most unfavourable real seismic design ground motion is introduced. Based on the concept, the most unfavourable real seismic design ground motions for rock, stiff soil, medium soil and soft soil site conditions are selected in terms of three typical period ranges of structures. The selected real strong motion records are suitable for seismic analysis of important structures whose failure or collapse will be avoided at a higher level of confidence during the strong earthquake, as they can cause the greatest damage to structures and thereby result in the highest damage potential from an extended real ground motion database for a given site. In addition, this paper also presents the real input design ground motions with medium damage potential, which can be used for the seismic analysis of structures located at the area with low and moderate seismicity. The most unfavourable real seismic design ground motions are verified by analysing the seismic response of structures. It is concluded that the most unfavourable real seismic design ground motion approach can select the real ground motions that can result in the highest damage potential for a given structure and site condition, and the real ground motions can be mainly used for structures whose failure or collapse will be avoided at a higher level of confidence during the strong earthquake. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
4.
地震作用下,饱和砂土地层地铁车站的动力反应特征是城市轨道工程抗震的关键问题。以太原地铁新近沉积粉细砂地层地铁工程为对象,通过模拟地震运动输入的饱和砂土地基地下结构的振动台模型试验,分析了不同峰值加速度地震作用下饱和砂土与地下结构相互作用的动力反应性状。研究了地震波作用的放大效应与频率特征,动孔压比增长发展过程和液化区域分布,以及动土压力的变化规律。表明加速度放大系数为1.5~2.0;0.1~0.25g峰值加速度地震作用下饱和砂土均产生动孔隙水压力累计发展;0.3g峰值加速度地震作用下饱和砂土产生液化,抑制了土与地下结构的振动放大效应,地表面大量冒水,结构模型出现了明显上浮,地下结构两侧产生震陷。 相似文献
5.
Downhole arrays are deployed to measure motions at the ground surface and within the soil profile, with some arrays instrumented to also record the pore pressure response within soft soil profiles during excitation. The measurements from these arrays have typically been used in conjunction with parametric and nonparametric inverse analysis approaches to identify soil constitutive model parameters for use in site response analysis or to identify averaged soil behavior between locations of measurement. The self-learning simulations (SelfSim) inverse analysis framework, previously developed and applied under total stress conditions, is extended to effective stress considerations and is employed to reproduce the measured motions and pore pressures from downhole arrays while extracting the underlying soil behavior and pore pressure response of individual soil layers. SelfSim is applied to the 1987 recordings from the Imperial Valley Wildlife Liquefaction Array. The extracted soil behavior suggests a new functional form for modeling the degradation of the shear modulus with respect to excess pore pressures. The extracted pore pressure response is dependent on the number and amplitude of shear strain cycles and has a functional form similar to current strain-based pore pressure generation models. 相似文献
6.
Pounding between adjacent bridge structures with insufficient separation distance has been identified as one of the primary causes of damage in many major earthquakes. It takes place because the closing relative movement is larger than the structural gap provided between the structures. This relative structural response is controlled not only by the dynamic properties of the participating structures but also by the characteristics of the ground excitations. The consequence of the spatial variation of ground motions has been studied by researchers; however, most of these studies were performed numerically. The objective of the present research is to experimentally evaluate the influence of spatial variation of ground motions on the pounding behaviour of three adjacent bridge segments. The investigation is performed using three shake tables. The input spatially varying ground excitations are simulated based on the New Zealand design spectra for soft soil, shallow soil and strong rock using an empirical coherency loss function. Results confirm that the spatially nonniform ground motions increase the relative displacement of adjacent bridge girders and pounding forces. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
7.
《地震研究进展（英文）》2022,2(4):100168
Based on the the large shaking table test results on irregular section subway station structure in soft soil, an overall time-history numerical simulation is conducted to study the nonlinear dynamic interaction of the soil-irregular underground structure. Typical test results, including the acceleration of the soil, acceleration, and deformation of the structure, were analyzed. Satisfactory consistency between the simulation and test results is verified, and the difference between these results was discussed in detail. The maximum inter-story drift ratio was approximately 1/472 under input PGA = 0.54 g. The strain responses of columns were significantly larger than those of the side walls and slabs. The components in the lower layers of the irregular subway station structure, particularly in the central columns, underwent cumulative damage. The research results could provide a simplified analysis method to quantitatively evaluate the damage of irregular underground structures in soft soil. 相似文献
8.
软土具有高灵敏度、低强度等特性,在地震过程中极易产生震陷。基于OpenSees数值模拟方法对软土场地的震陷反应进行非线性动力有限元分析,通过改变地震动峰值加速度、频谱特性、输入方式来研究其对软土震陷的影响。结果表明,地震动峰值加速度对地基土的不均匀震陷有显著影响,地震动峰值加速度越大,震陷量显著增大,震陷影响深度更大,对水平地表造成的破坏范围也更大;地震动频谱特性对软土震陷有重要影响,当地震动卓越频率与场地自振频率相近时,其幅值越大,产生的震陷越严重;水平、竖向同时输入地震动的方式能更好地反映土体的振动及震陷响应。该研究成果对探索软土震陷的机理有一定的指导意义。 相似文献
9.
液化场地土-地铁车站结构大型振动台模型试验研究 总被引：5，自引：2，他引：5
本文对浅埋于可液化南京细砂地基中的地铁车站结构进行了大型振动台试验研究,对部分试验结果进行了整理,分析了模型地基的加速度和振动孔隙水压力的反应规律。试验结果表明:在整个试验过程中,模型地基浅层土和地铁车站侧向附近地基土最容易发生液化;其次,随着振动台台面输入地震动峰值加速度的增大,离车站结构较远的侧向地基土和底层地基土再发生液化,而车站结构正下方的模型地基土最不容易液化。同时,在模型地基土发生液化后,地铁车站结构发生了明显的整体上浮现象。 相似文献
10.
The seismic response of the Mexico City Cathedral built of very soft soil deposits is evaluated by using motions recorded in various parts of the structure during several moderate earthquakes. This unique set of records provides significant insight into the seismic response of this and other similar historic stone masonry structures. Free‐field ground motions are carefully compared in time and frequency domains with motions recorded at building basement. The dynamic characteristics of the structure are inferred from the earthquake records by using system identification techniques. Variation of seismic response for different seismic intensities is discussed. It is shown that, due to the soil–structure interaction, due to large differences between dominant frequencies of earthquake ground motions at the site and modal frequencies of vibration of the structure, and due to a particularly high viscous damping, seismic amplifications of ground motion in this and similar historic buildings erected on soft soil deposits are much smaller than that induced in most modern constructions. Nevertheless, earthquake records and analytical results show that several components of the structure such as its central dome and the bell towers may be subjected to local vibrations that significantly amplify ground motions. Overall, results indicate that in its present state the structure has an acceptable level of seismic safety. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
11.
为了解软土自由场地地震反应特性,开展饱和软土自由场地地震反应特性大型振动台模型试验。分别从模型体系自振特性、震陷位移及不同土层深度测点的加速度、动孔压比等动力响应指标方面,较为深入和全面地分析饱和软土自由场地地震反应规律、破坏机理。同时还分析模型箱的"边界效应"以验证试验土箱的合理性、有效性和测试仪器性能,并由此进一步确定模型地基有效工作区域。研究表明:(1)地震动作用下,饱和软土自由场地特征频率降低,阻尼增大;(2)饱和软土自由场地对水平输入地震波具有短周期滤波、长周期放大效应,且强震作用下地基失效并表现为减隔震作用;(3)饱和软土自由场地动孔压比优势区域位于浅埋土层,并随着输入地震动强度的增大,该区域动孔压比优势逐渐减弱。该研究可为非自由软土场地试验研究提供必要的技术经验。 相似文献
12.
以甘肃兰州地铁一号线某地铁车站为工程背景,基于ADINA分析软件32CPU有限元显式计算平台,建立地基土与车站结构相互作用的非线性地震响应计算模型。数值分析在El-Centro、Kobe和兰州波的多遇地震条件下其车站及地基土的动力响应差异。结果表明:车站结构振型与周围地基土振型基本一致;车站底板、中板及顶板的加速度时程曲线形状基本相同;中柱和侧墙均随着埋深的增加其水平位移减小;车站周围的地表土体均发生了不同程度的沉降,其距车站7.5m范围的沉降尤为显著,致使周围建筑物会遭受到一定程度的损坏。 相似文献
13.
土-结构相互作用效应对结构基底地震动影响的试验研究 总被引：3，自引：0，他引：3
利用土与结构动力相互作用振动台模型试验数据,通过各种试验工况下土层表面与基础表面加速度反应的比较,深入探讨了土与结构动力相互作用效应对高层建筑结构基底地震动的影响。从输入地震动频谱特性、输入地震动强度水平和上部结构动力特性3个方面详细分析了与SSI效应对高层建筑基底震动影响程度有关的一些因素。结果表明：SSI效应对高层建筑基底地震动的影响与输入地震波的动力特性有很大关系。在地震动的频谱成分方面,SSI效应对高层建筑基底地震动的影响主要体现为土层表面和基础表面在与输入地震动卓越频率相近处的频谱成分有较大差异;SSI效应对高层建筑基底地震动的影响程度随着输入加速度峰值水平的增加而减小;在某一特定地震波作用下,当上部结构的振动频率与地震地面运动的卓越频率相近时,SSI效应对高层建筑基底地震动的影响较为强烈。 相似文献
14.
Kuo-Liang Wen 《地震工程与结构动力学》1994,23(6):599-608
From both theoretical and empirical studies, we know that a soft soil layer will amplify seismic waves of certain frequencies and cause damage to structures, depending on the physical properties and the thickness of the layer. Most developed cities are situated on a plane or a basin with soft geological strata. Thus, understanding the characteristics of soft soil response to seismic loading is important. Seismologists and engineers are interested in questions of linear versus non-linear soil response and isotropy versus anisotropy as a soil property. The records of the downhole accelerographs of an array in Lotung provide an opportunity to study these problems. The results show that the soil response in Lotung does not have an anisotropy effect, and significant non-linear soil response occurred during the strong ground motions in which peak ground acceleration values at ground surface are larger than 150 gal. 相似文献
15.
It is well known that the generation of excess pore water pressure and/or liquefaction in foundation soils during an earthquake often cause structural failures.This paper describes the behavior of a small-scale braced wall embedded in saturated liquefiable sand under dynamic condition.Shake table tests are performed in the laboratory on embedded retaining walls with single bracing.The tests are conducted for different excavation depths and base motions.The influences of the peak magnitude of the ground motions and the excavation depth on the axial forces in the bracing,the lateral displacement and the bending moments in the braced walls are studied.The shake table tests are simulated numerically using FLAC 2D and the results are compared with the corresponding experimental results.The pore water pressures developed in the soil are found to influence the behavior of the braced wall structures during a dynamic event.It is found that the excess pore water pressure development in the soil below the excavation is higher compared to the soil beside the walls.Thus,the soil below the excavation level is more susceptible to the liquefaction compared to the soil beside the walls. 相似文献
16.
Zhang Jianlei Cheng Qiangong Li Yan Qiu Yuheng Wang Yufeng Wu Jiujiang 《地震工程与工程振动(英文版)》2021,20(4):905-923
The performance of rectangular closed diaphragm walls(RCDW) subjected to earthquake ground motions is extremely complicated in gently sloping liquefiable deposits and requires further investigation. A nonlinear finite element(FE) model was developed to investigate the seismic performance of an RCDW in the OpenSees platform. Initially, the feasibility of the FE model to simulate the seismic behavior of the RCDW was validated by comparing the numerical results with the experimental data. The numerical results agree well with the centrifuge test data. Then, the calibrated model was used to study the seismic performance of the RCDW subjected to different ground motions in gently sloping liquefiable deposits.The numerical results indicate that the soil-RCDW system under near-fault ground motions is more likely to be damaged than that under far-fault ground motions. The difference between the maximum and minimum(D_(max-min)) the RCDW displacement and the maximum excess pore pressure in the soil core increased as the Arias intensity increased. The seismic response of the soil-RCDW system was strongly affected by the frequency content, durations, energy distribution and initial directions of the ground motions. Moreover, the modified specific energy density(MSED) has a good linear relationship with the D_(max-min) of the RCDW displacement. 相似文献
17.
The evaluation of seismic pile response is particularly useful for geotechnical engineers involved in the design of foundations in liquefying site. Shake table testing was performed to study the dynamic interactive behavior of soil–pile foundations in liquefying ground under different shaking frequency and amplitude. The soil profile consisted of a clayey layer over liquefiable sand over clay. The model was tested with a series of El Centro earthquake motions with peak accelerations ranging from 0.15g to 0.50g, and time step from 0.006 to 0.02 s. Representative data, including time histories of accelerations and excess pore pressure ratios that characterize the important aspects of soil–pile interaction in liquefying ground are presented. The shaking frequency has no significant effect on the magnitudes of excess pore pressure ratio, ground and pile accelerations and pile bending moments. Excess pore pressure ratio, ground acceleration and pile acceleration, and pile bending moment largely depend on the shaking amplitude. 相似文献
18.
Masoud Moghaddasi Misko Cubrinovski J. Geoff Chase Stefano Pampanin Athol Carr 《地震工程与结构动力学》2011,40(2):135-154
Complex seismic behaviour of soil–foundation–structure (SFS) systems together with uncertainties in system parameters and variability in earthquake ground motions result in a significant debate over the effects of soil–foundation–structure interaction (SFSI) on structural response. The aim of this study is to evaluate the influence of foundation flexibility on the structural seismic response by considering the variability in the system and uncertainties in the ground motion characteristics through comprehensive numerical simulations. An established rheological soil‐shallow foundation–structure model with equivalent linear soil behaviour and nonlinear behaviour of the superstructure has been used. A large number of models incorporating wide range of soil, foundation and structural parameters were generated using a robust Monte‐Carlo simulation. In total, 4.08 million time‐history analyses were performed over the adopted models using an ensemble of 40 earthquake ground motions as seismic input. The results of the analyses are used to rigorously quantify the effects of foundation flexibility on the structural distortion and total displacement of the superstructure through comparisons between the responses of SFS models and corresponding fixed‐base (FB) models. The effects of predominant period of the FB system, linear vs nonlinear modelling of the superstructure, type of nonlinear model used and key system parameters are quantified in terms of different probability levels for SFSI effects to cause an increase in the structural response and the level of amplification of the response in such cases. The results clearly illustrate the risk of underestimating the structural response associated with simplified approaches in which SFSI and nonlinear effects are ignored. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
19.
Study on wall-type gravel drains as liquefaction countermeasure for underground structures 总被引：1，自引：0，他引：1
R. P. Orense I. Morimoto Y. Yamamoto T. Yumiyama H. Yamamoto K. Sugawara 《Soil Dynamics and Earthquake Engineering》2003,23(1):114
One of the most dramatic causes of damage to engineering structures during earthquakes has been the development of soil liquefaction beneath and around the structures. In order to dissipate the excess pore water pressures near structures, gravel drains are usually employed. In this study, the use of recycled concrete crushed stones as gravel drain materials is addressed. In order to investigate the performance of wall-type gravel drains, two series of shaking table tests were performed. The test results showed that gravel drains, when appropriate grain size distribution is considered, effectively dissipate the excess pore water pressure underneath the structure, and consequently reduce the magnitude of uplift. To supplement the laboratory tests, finite element analyses were also performed. For specified structure, ground and earthquake conditions, there is a critical width of gravel drain at which no uplift of structure will occur. The results of the model tests and the finite element analyses were then employed in developing design charts for determining the critical width of gravel drain to prevent buoyant rise of structure when the surrounding soil mass liquefies. 相似文献
20.
地铁循环荷载作用下饱和软黏土的动力特性研究对于揭示软黏土在地铁荷载下的孔压、强度以及变形模式具有重要意义,可以为控制地铁长期沉降、降低运营风险提供理论依据。试验加载形式的不同会带来不同的动力特性表征,需选取最能反映地铁列车真实性质的荷载形式。本文在列车荷载作用下研究土动力特性,采用室内动三轴试验的方法,对比分析不同形式下动力荷载作用效果。试验研究表明:偏压正弦波可以作为简化波形研究列车荷载,它不仅可以确保加载过程中地基土只有压应力,而且能较好地模拟列车循环荷载。 相似文献