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1.
Based on the requirement of seismic reinforcement of bridge foundation on slope in the Chengdu-Lanzhou railway project, a shaking table model test of anti-slide pile protecting bridge foundation in landslide section is designed and completed. By applying Wenchuan seismic waves with different acceleration peaks, the stress and deformation characteristics of bridge pile foundation and anti-slide pile are analyzed, and the failure mode is discussed. Results show that the dynamic response of bridge pile and anti-slide pile are affected by the peak value of seismic acceleration of earthquake, with which the stress and deformation of the structure increase. The maximum dynamic earth pressure and the moment of anti-slide piles are located near the sliding surface, while that of bridge piles are located at the top of the pile. Based on the dynamic response of structure, local reinforcement needs to be carried out to meet the requirement of the seismic design. The PGA amplification factor of the surface is greater than the inside, and it decreases with the increase of the input seismic acceleration peak. When the slope failure occurs, the tension cracks are mainly produced in the shallow sliding zone and the coarse particles at the foot of the slope are accumulated. 相似文献
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为了研究地震时地面运动加速度作用下高层房屋建筑深基坑支护承压结构的局部抗震性能，针对高层房屋建筑深基坑支护承压结构进行局部抗震性试验分析。采用有限元软件对某高层房屋建筑深基坑工程进行分析，构建高层房屋建筑深基坑支护承压结构有限元计算模型。利用地震模拟振动台，分别输入0.4g、0.5g、0.6g的地震时地面运动加速度，测试不同深基坑施工阶段和插入比地下连续墙深基坑支护承压结构的抗震性能，并研究不同地震烈度对深基坑支护承压结构位移的影响。通过振型分解反应谱法，获取高层房屋建筑深基坑支护承压结构位移以及加速度响应，实现高层房屋建筑深基坑支护承压结构局部抗震性能测试。试验结果表明，高层房屋建筑深基坑支护承压结构的抗震稳定性与深基坑开挖深度、插入比和地震烈度有关。其中，深基坑开挖深度和地震烈度与高层房屋建筑深基坑支护承压结构的抗震稳定性成反比，而插入比与高层房屋建筑深基坑支护承压结构的抗震稳定性成正比，且能够有效提高高层房屋建筑深基坑支护承压结构的抗震性能。 相似文献
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Shaking Table Test Study on Dynamic Characteristics of Bridge Foundation Reinforcement on Slopes 总被引：3，自引：3，他引：0
With the fast development of bridge construction in mountainous and seismic areas, it is necessary to conduct related research. Based on the design of a shaking table model test, here are the following test results:the filtering effect exists in soil and is affected by the dynamic constraint conditions, the amplitude is strengthened around the natural frequency and weakened in other frequency bands in the Fourier spectrum. Since the acceleration scaling effect occurred on a sloped surface, the acceleration response decreases from the outside to the inside in soil. The dynamic response is relatively strong near the slip surface in bedrock due to the reflection of seismic waves. The failure mode of landslide is decided by the slope angle and slipping mass distribution, and the test shows the front row stabilizing piles should keep a proper distance from bridge foundation so that seismic resistance can be guaranteed for the bridge foundation. 相似文献
4.
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
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To investigate the seismic response of a pile group during liquefaction, shaking table tests on a 1/25 scale model of a 2 × 2 pile group were conducted, which were pilot tests of a test project of a scale-model offshore wind turbine with jacket foundation. A large laminar shear box was utilized as the soil container to prepare a liquefiable sandy ground specimen. The pile group model comprising four slender aluminum piles with their pile heads connected by a rigid frame was designed with similitude considerations focusing on soil–pile interaction. The input motions were 2-Hz sinusoids with various acceleration amplitudes. The excess pore water pressure generation indicated that the upper half of the ground specimen reached initial liquefaction under the 50-gal-amplitude excitation, whereas in the 75-gal-amplitude test, almost entire ground was liquefied. Accelerations in soil, on the movable frames composing the laminar boundary of the shear box, and along the pile showed limited difference at the same elevation before liquefaction. After liquefaction, the soil and the movable-frame accelerations that represented the ground response considerably reduced, whereas both the movable frames and the piles exhibited high-frequency jitters other than 2-Hz sinusoid, and meantime, remarkable phase difference between the responses of the pile group and the ground was observed, all probably due to the substantial degradation of liquefied soil. Axial strains along the pile implied its double-curvature bending behavior, and the accordingly calculated moment declined significantly after liquefaction. These observations demonstrated the interaction between soil and piles during liquefaction. 相似文献
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Development of new drain method for protection of existing pile foundations from liquefaction effects 总被引：1，自引：0，他引：1
Naoyuki Harada Ikuo Towhata Tadashi Takatsu Shinsuke Tsunoda Vlatko Sesov 《Soil Dynamics and Earthquake Engineering》2006,26(2-4):297-312
Pile foundation as well as other underground structures could be seriously affected by soil liquefaction during strong earthquakes. Damages on pile foundation due to liquefaction can be reduced by implementation of some soil improvement method. Main objective of present study is developing of drain method that can improve the soil in order to mitigate the destructiveness of liquefaction on superstructure supported by pile foundation. Series of shaking table tests were conducted on 2×2 pile foundation and soil model was improved by drains. Configurations of drains around piles, intensity of shaking were one of the parameters that were changing during the tests in order to investigate the response of pile foundation in improved soil condition.Shaking table tests and performed On-site experiment showed the following effects of the new drain method. (1) When the intensity of earthquake motion is 200 gal or less, generation of excess pore water pressure is reduced and the pile bending moment is decreased, (2) when the intensity of earthquake motion is stronger (300 gal or more), drainage effect prevents disappearance of subgrade reaction, and (3) proposed new type of drain can control excess pore water pressure without clogging. 相似文献
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为了分析软土地基－筏基础核电厂房结构地震反应规律和特征,利用地震模拟振动台开展了软土地基－筏基础－核电厂房动力相互作用问题的试验研究。分别进行了表面水平土体模型和表面凹陷土体模型的运动相互作用试验、地基土－筏基础－核电厂房振动台相互作用试验、核电厂房直接固定在振动台面上的刚性基底振动台试验。试验采用圆形叠层剪切模型箱,地基土模型为某工程场地的均匀粉质粘土,其剪切波速为213 m/s;核电厂房简化为3层框架剪力墙结构模型。试验输入波形为美国核电规范常用的RG1.60反应谱合成得到的人工地震动时程。振动台试验结果对比分析表明:土－结构体系中系统的振动周期和阻尼明显大于刚性基底下结构的振动周期和阻尼;相同地震作用下在土－结构动力相互作用体系中结构加速度明显小于刚性基底下的结构加速度反应;而位移明显大于刚性基底下结构的位移。本文的研究成果可为软土地基建立核岛厂房的适应研究提供参考。 相似文献
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饱和粉土液化特性的大型振动台模型试验研究 总被引：3，自引：0，他引：3
京沪高速铁路徐沪段路基的粉土粘粒含量少于1.5%、粉粒含量约为80%,在强烈地震作用下存在着液化可能性.为充分研究这一饱和粉土地层的液化特性,本文作者利用大型地震模拟振动台,进行了模拟自由场地饱和粉土的地震液化模型试验,试验结果再现了自然地震触发的粉土液化的各种宏观震害现象,揭示了饱和粉土的地震液化规律和特征。试验结果为京沪高速铁路徐沪段路基的抗震设计提供了参考依据。 相似文献
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《震灾防御技术》2022,17(4):643-650
利用振动台模型试验和有限元数值模拟的方法对土质地基-群桩-钢框架结构体系动力相互作用的规律和特征进行研究,并讨论了基桩长径比对于体系动力相互作用特征的影响。试验地基土体模型为均匀粉质黏土,剪切波速约为213 m/s;群桩基础由9根长2.0 m、直径0.1 m的基桩3×3对称布置;上部结构模型简化为三层钢框架结构。本文研究结果表明:土-桩-钢框架结构体系的阻尼比相较固定基础情形有所增加,输入相同地震动时其地震反应小于固定基础情形;动力相互作用体系中运动相互作用的贡献与惯性相互作用相当,不应忽略;随着基桩长径比的增大,运动相互作用增大,钢框架结构的加速度反应增大。 相似文献
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弹塑性位移谱法的振动台模型试验验证 总被引：2，自引：0，他引：2
弹塑性位移谱法求解结构在指定强度地面运动作用下的位移需求是一种简便合理的方法。本文将弹塑性位移谱法就具体地震波计算的楼层位移需求、层间位移角需求与一比例为1／10的12层钢筋混凝土模型框架振动台试验结果作了比较。设计的12层钢筋混凝土模型框架结构在振动台上经历了7种强度等级地震波的作用,输入峰值加速度依次为：0．090g、0．258g、0．388g、0．517g、0．646g、0．775g和0．904g。求出了弹塑性位移谱法计算的楼层位移和层问位移角需求与振动台试验结果的比值,研究了二者比值的均值及方差沿楼层的分布情况。结果表明：弹塑性位移谱法的计算结果与振动台得到的位移需求值吻合较好,在基于性能的抗震设计中具有较好的应用前景。 相似文献
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土石坝振动台模型试验颗粒流数值模拟分析 总被引：2，自引：0，他引：2
目前一般采用振动台试验、离心振动台试验和有限元动力分析来获得土石坝在设计地震荷载作用下的形态和抗震性能。本文结合孔宪京等的土石坝振动台试验结果开展了颗粒流细观数值模拟研究,克服了传统连续介质力学的宏观连续性假设,形象而直观地表现出坝体在动力荷载作用下的破坏特征。数值模拟规律与振动台试验规律基本一致。同时还分析了坝体颗粒粘结强度和地震峰值加速度变化对坝体破坏特征的影响。数值结果表明,当颗粒间粘结强度较低时,表现为坝体表面颗粒的滑动破坏,粘结强度稍大时,会出现局部的小块颗粒团整体滑动破坏;随着峰值加速度的增大,坝顶沉降量在增大,坝体破坏特征不变。 相似文献
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针对核电厂CAP1400核岛结构地震反应问题，构建了核岛屏蔽厂房和辅助厂房整体结构的3个分析模型:原型和1/16、1/40缩尺模型，并在AP000谱和RG1.60谱地震动输入下进行了有限元模拟对比分析，探讨了振动台试验模型缩尺处理的合理性和精确性。研究表明，基于缩尺模型得到的结构自振频率相对于原型结构模型有所降低，降低幅度在8.5%以内；结构模型的缩尺对结构反应峰值加速度和高频（大于3Hz）加速度反应谱的影响较为显著，但对较低频（小于3Hz）的加速度反应谱影响较小；模型缩尺对结构不同方向反应的影响中，刚度越大的方向其影响越大。进一步将结构模型数值模拟结果与1/16缩尺模型的振动台试验结果进行了比较分析，试验给出的结构自振频率远低于模型数值模拟结果，但原型和1/16缩尺模型数值模拟得到的结构反应均与试验结果较为接近。基于模型数值模拟和振动台试验研究，认为对于缩尺比1/16或更大的模型可以忽略模型的缩尺效应。 相似文献
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在北京工业大学振动台台阵系统上开展了一系列锯末混合土地基自由场振动台模型试验,试验中模型箱采用装配式连续体刚性模型箱,试验中输入地震动时程采用El Centro地震动记录、Taft地震动记录和天津地震动记录,地震动输入方向分为水平单向和水平双向。文中,重点考察了双向地震动输入下锯末混合土模型场地的动力特性及其变化规律,主要指标包括模型场地地震动反应的峰值加速度及其动力放大系数、加速度时程及其傅氏谱。试验结果表明:随着输入地震动强度的增大,同一测点反应的峰值加速度总体上在增大,而其加速度动力放大系数总体上呈现减小的趋势,反应的频谱组成从较高频率向较低频率移动;双向地震作用下锯末混合土模型场地的动力变化规律与单向地震作用下较为一致。 相似文献
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通过对农村民居特点的研究,提出一种新型、经济、简单、可靠的隔震技术—钢筋-沥青复合隔震墩.根据相关理论设计了相应的隔震墩试件.通过地震模拟振动台试验输入E1 Centro和Taft地震动与结构地震反应的对比,研究了钢筋-沥青复合隔震墩模型的振动特性.试验结果表明,隔震墩加速度折减系数在0.34 ～ 0.55之间,可有效... 相似文献
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The effect of soil inhomogeneity and material nonlinearity on kinematic soil–pile interaction and ensuing bending under the passage of vertically propagating seismic shear waves in layered soil, is investigated by means of 1-g shaking table tests and nonlinear numerical simulations. To this end, a suite of scale model tests on a group of five piles embedded in two-layers of sand in a laminar container at the shaking table facility in BLADE Laboratory at University of Bristol, are reported. Results from white noise and sine dwell tests were obtained and interpreted by means of one-dimensional lumped parameter models, suitable for inhomogeneous soil, encompassing material nonlinearity. A frequency range from 0.1 Hz to 100 Hz and 5 Hz to 35 Hz for white noise and sine dwell tests, respectively, and an input acceleration range from 0.015 g to 0.1 g, were employed. The paper elucidates that soil nonlinearity and inhomogeneity strongly affect both site response and kinematic pile bending, so that accurate nonlinear analyses are often necessary to predict the dynamic response of pile foundations. 相似文献
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桩板式挡土结构由抗滑桩发展而来,可用于一般地区、浸水地区和地震区的边坡工程支挡;对于地震区边坡,采用单排或双排支挡结构的形式及其支挡效果尚缺少深入研究。本文基于地震力作用下单排、双排桩板结构在不同加载等级时的桩身土压力、土体加速度、桩身位移等变化的振动台模型试验结果,对比采用单排、双排桩板结构边坡的支挡效果,得出静力状态和不同加速度峰值地震力作用桩前后土压力分布、桩后土体加速度分布和桩体位移的一些规律,为今后边坡桩板式支挡结构的抗震设计提供参考。 相似文献
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根据已经完成的液化侧向扩展场地-群桩基础-上部结构体系大型振动台试验,在有限元软件OpenSees中建立了可液化倾斜场地振动台试验的有限元模型。通过与试验结果对比,验证了数值模型的可靠性。基于此,建立了典型水平和倾斜液化场地-桩基-桥梁结构体系的数值模型,讨论了双向地震作用下水平和倾斜场地体系地震响应的差异,结果表明:相比水平场地,倾斜场地超孔隙水压力在峰值阶段波动幅度更大,土体的侧向位移增加明显,尤其是在饱和砂土中部位置;倾斜场地中桩基础的破坏程度更大,可液化层中部桩基曲率最大可增大约13倍,桩身水平位移显著增加;而水平场地桥墩曲率比倾斜场地桥墩曲率大,建议在液化场地桩基设计中应考虑场地倾斜带来的影响。 相似文献
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R. Uzuoka M. Cubrinovski H. Sugita M. Sato K. Tokimatsu N. Sento M. Kazama F. Zhang A. Yashima F. Oka 《Soil Dynamics and Earthquake Engineering》2008,28(6):436-452
The 1995 Kobe earthquake seriously damaged numerous buildings with pile foundations adjacent to quay walls. The seismic behavior of a pile group is affected by movement of quay walls, pile foundations, and liquefied backfill soil. For such cases, a three-dimensional (3-D) soil–water coupled dynamic analysis is a promising tool to predict overall behavior. We report predictions of large shake table test results to validate 3-D soil–water coupled dynamic analyses, and we discuss liquefaction-induced earth pressure on a pile group during the shaking in the direction perpendicular to ground flow. Numerical analyses predicted the peak displacement of footing and peak bending moment of the group pile. The earth pressure on the pile in the crustal layer is most important for the evaluation of the peak bending moment along the piles. In addition, the larger curvatures in the bending moment distribution along the piles at the water side in the liquefied ground were measured and predicted. 相似文献