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埋地管道地震作用下的破坏因素源于地震引起的永久地面变形(PGD),其中管道-土体间相互作用决定土体位移作用到管体的大小。利用离心机试验技术模拟埋地管道在逆断层大位移下的反应特性,重点讨论断层与管道的交角、断层位移大小、管土相互作用、管径和埋深五个参数对管道破坏的影响水平。实验结果表明:上述参数对管道断层作用的反应均有明显影响,其中断层的位移量、管土相互作用、埋深和管径的影响更为显著。本文的研究结果对于管道经过断层区的抗震设计有十分重要的意义。 相似文献
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砂土液化是埋地管道遭受地震破坏的主要原因之一。液化土对管道产生上浮力,使管道发生上浮反应,它是随地震发生时间而变化的动态过程。将地震载荷作用下的液化区埋土管道模拟成两端弹性支承的直梁模型,考虑管-土间的相互作用和管内流体与管道之间的流固耦合作用,采用模态叠加法对液化区埋地管道进行地震响应的动态分析,探讨了管道和液化土参数对管道动态上浮反应的影响。通过数值仿真得到了管内流体的流速、流体压力、流体密度、管截面轴向力,管道黏弹系数、液化土容重和相对弹簧系数、地震加速度幅值等因素对管道上浮位移的影响情况。 相似文献
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《地震工程与工程振动》2015,(3)
基于多子台台阵系统,北京工业大学于近期开展了多点地震动输入、不同场地条件下埋地管道振动台试验。试验中连续体模型箱固定于3个振动台台面上,相邻台面上的箱体能在水平双方向(纵向、横向)相对运动;3个振动台相互独立,通过分别对3个振动台输入各自的加速度记录实现了多点地震动输入。本文针对其中的横向水平地震激励作用下的场地响应进行研究,分析了一致和非一致地震作用下有无埋地管线时的场地地震响应规律。试验结果表明,非一致激励作用将增大场地土体的相对位移,致使相邻地震动输入点间场地土体受到剪切作用;随着输入地震动强度的增加,场地土体的一阶固有频率持续降低,阻尼比不断增大;非自由场的阻尼比、一阶固有频率等参数略大于自由场。 相似文献
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管土摩擦和管径对埋地管道破坏的影响分析 总被引：8，自引：0，他引：8
如何分析管土摩擦和管径对埋地管道地震破坏的影响,是城市地下管道建设中面临的突出问题。采用AD INA软件的定义体操作来选择体类型,并应用布尔操作实现了管道与土体和断层之间的融合,得到地下管道破坏分析的几何模型。通过模型参数选择,确定了岩土性质、管道特性、断层等模型参数,定义了管土摩擦、地震荷载时间函数、断层位移荷载。依据计算结果,分析了管土摩擦和管径对地下管道地震破坏的影响,找出了提高埋地管道抵抗破坏能力的摩擦系数和管径最优值,给出了几点工程建议。 相似文献
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本文将管线周围的土体视为固-液二相介质，采用考虑地震过程中土体内孔隙水压力的增长和消散的有效应力分析方法，并以非线性的土体本构模型模拟土体动力特性的改变以及在孔隙水压作用下的变形，以求接近土体的真实地震反应。研究表明随着土体软化程度的不同，受到土体约束的管线应力亦发生相应变化。文中详细研究了地震动峰值、管线直径、行波波速和入射角度等对管线应力的影响。 相似文献
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考虑动水压力影响的单柱式桥墩地震反应分析 总被引：3，自引：1，他引：2
在Morison方程的基础上,用附加水质量法考虑动水压力对桥墩的影响,以单柱式桥墩为研究对象,以ABAQUS有限元软件为计算平台,建立了考虑桩-土动力相互作用的单柱式桥墩地震反应分析模型,考虑土体和桥墩混凝土的动力非线性特征,分析了地震动作用下动水压力对单柱式桥墩的墩顶相对墩底位移、加速度、剪力和弯矩反应的影响,并探讨了水位对单柱式桥墩地震反应特性的影响。结果表明:动水压力改变桥墩的地震反应特性,增大了桥墩顶部相对底部的位移、墩顶绝对加速度和墩底的内力,水位变化影响桥墩的地震反应特性。对于深水桥墩抗震设计计算,考虑动水压力效应、水位变化是有必要的。 相似文献
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穿越逆冲断层的埋地管道非线性反应分析 总被引：2，自引：0，他引：2
穿越逆冲断层的埋地管道在地震作用下,容易发生局部屈曲或整体失稳等形式的破坏,研究逆冲断层作用下的埋地管道地震反应规律,对管道抗震设计及施工等具有重要的意义。本文将埋地管线及周围土体从半无限地球介质中取出,分别以空间薄壳单元和实体单元进行离散,采用非线性接触力学方法模拟管、土之间的滑移、分离及闭合现象;采用线性位移加载模拟断层的错动,考虑了系统初始应力状态的影响,对土体未开裂前的管土相互作用系统进行了拟静力数值分析;分析了位错量、土体刚度、埋设深度、径厚比及跨越角度对埋地管道反应的影响,得出了一些有益的结论。 相似文献
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土体沉陷是引起埋地管道破坏的重要原因之一,它会引起穿越该沉陷区域的大口径地下管道屈曲失稳,使管道在没有达到拉伸或剪切强度前便退出工作.将管道与周围土体从半无限土体介质中共同取出,建立沉陷作用下的管土相互作用模型.管道以薄壳单元模拟,土体采用实体单元进行离散,采用特征值屈曲分析方法对沉陷区域埋地管道的屈曲稳定性进行了分析,给出了管道发生屈曲时的屈曲模态及对应的沉降量.研究沉陷区长度、管道埋深、管径、壁厚及场地条件等对管道屈曲反应的影响.在文中所用模型与假设条件下发现地下管线埋深较浅时更易发生屈曲失稳,管道径厚比越大管道越易发生屈曲,场地土体越硬管道越易发生屈曲失稳等结论. 相似文献
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Pipelines buried in saturated sand deposits, during earthquake loading could damage from resulting uplift due to excess pore water pressure generation. Several studies have been made to better understand the uplift mechanism and evaluate the effectiveness of mitigating techniques through experiment, but little numerical works have been done to assess the influence of soil properties and field conditions in pipeline floatation. Especially for previously buried pipelines, in order to set the priority for seismic retrofit, evaluating the risk of floatation in each region could be a concern. In this paper, effects of several parameters including dilatancy angle and density ratio of natural soil, diameter and burial depth of pipe, underground water table and thickness of the saturated soil layer on uplift of pipe have been investigated. Results show the prominent role of burial depth in pipe response and that there exits an optimum level for drop of water table to reduce floatation. 相似文献
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砂土自由场地震响应的离心机试验研究 总被引：2，自引：1，他引：2
离心机模型试验是研究岩土地震工程问题的有效手段。本文使用层状剪切箱,通过干落法制备了均匀的砂土模型,进行了离心机振动试验;观测了振动过程中孔隙水压力的发展,土体的加速度响应、侧向变形以及竖向沉降。结果表明,土体的运动和变形与孔隙水压力的发展密切相关,但离心机中的试验现象和现场观测的现象存在显著区别。研究结果增强了对振动过程中土-水之间相互作用机理的理解,同时为自由场地震响应分析方法的验证提供了基础数据。 相似文献
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地震断层作用下的埋地管道等效分析模型 总被引：2，自引：0，他引：2
地震作用下,活动断层附近的埋地管道易发生强度屈服、局部屈曲或整体失稳等形式的破坏,建立准确、高效的埋地管道在断层作用下的计算模型,对管道的抗震设计和震后安全状态评估具有重要的实用价值。本文采用非线性弹簧模拟远离断层处埋地管道的反应,基于管土之间小变形段管道处于强化阶段,提出一种改进的管土等效分析模型,进一步减小了管土之间大变形段的分析长度,从而提高了有限元分析效率。该模型采用ALA推荐的方法计算管土间的滑动摩擦力,可以考虑土体种类的影响;用Kennedy方法确定管道的计算长度。通过与精确模型比较,验证了管土等效模型的合理性和有效性。 相似文献
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受沉陷作用埋地管道破坏判别方法 总被引：2，自引：0，他引：2
大地地震震害经验表明，场地的不均匀沉陷是导致埋地管线破坏地重要原因之一。提出一个适用的管道破坏判别方法十分重要本文提出了一个新的方法，用以分析受沉的埋地管道的反应，该方法发迹了沉陷区和非沉陷区都用弹性地基梁的分析途径，在沉陷区考虑了管道几何大变形，克服了现有方法公适用于无限远处发生最大沉陷的缺陷，适用于任何沉陷参数的情况。 相似文献
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The evaluation of the wave-induced pore pressure around a buried pipeline is particularly important for pipeline engineers involved in the design of offshore pipelines. Most previous investigations of the wave-induced dynamic response around an offshore pipeline have limited to two-dimensional cases. In this paper, a three-dimensional model including buried pipeline is established, based on the existing DYNE3WAC models. Based on the proposed numerical model and poro-elastic soil material assumption, the effects of wave and soil characteristics, such as wave period, water depth, shear modulus and permeability, and configuration of pipelines, such as pipeline radius and pipeline buried depth, on the wave-induced excess pore pressure will be examined. Numerical results indicated that the normalized excess pore pressures versus z/h near the pipeline increase as the obliquity angle, wave period and water depth increase, and they decrease as the burial depth and radius of pipeline increase above the pipeline. Soil permeability has obvious influence on the wave-induced normalized excess pore pressure, and different soil material will result in distinct computation results. 相似文献
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To estimate the demand of structures, investigating the correlation between engineering demand parameters and intensity measures (IMs) is of prime importance in performance-based earthquake engineering. In the present paper, the efficiency and sufficiency of some IMs for evaluating the seismic response of buried steel pipelines are investigated. Six buried pipe models with different diameter to thickness and burial depth to diameter ratios, and different soil properties are subjected to an ensemble of 30 far-field earthquake ground motion records. The records are scaled to several intensity levels and a number of incremental dynamic analyses are performed. The approach used in the analyses is finite element modeling. Pipes are modeled using shell elements while equivalent springs and dashpots are used for modeling the soil. Several ground motion intensity measures are used to investigate their efficiency and sufficiency in assessing the seismic demand and capacity of the buried steel pipelines in terms of engineering demand parameter measured by the peak axial compressive strain at the critical section of the pipe. Using the regression analysis, efficient and sufficient IMs are proposed for two groups of buried pipelines separately. The first one is a group of pipes buried in soils with low stiffness and the second one is those buried in soils with higher stiffness. It is concluded that for the first group of pipes, \(\sqrt {{\text{VSI}}[\upomega_{1} ({\text{PGD}} + {\text{RMS}}_{\text{d}} )]}\) followed by root mean square of displacement (RMSd) are the optimal IMs based on both efficiency and sufficiency; and for the second group, the only optimal IM is PGD2/RMSd. 相似文献
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When designing buried structures using a performance-based framework, it is important to estimate their uplift displacement. A simplified method is proposed for predicting the uplift displacement of a hollow cylinder structure buried in shallow backfill based on the equilibrium of vertical forces acting on the structure during earthquakes. However, this method only provides the maximum value, which frequently is overestimated in practical applications. To offset this limitation, first, the uplift behavior of buried hollow cylinder structures subjected to strong earthquake motions was simulated. Then, two-dimensional effective stress analyses based on the multiple shear mechanism for soil were conducted, and the results were compared with the centrifuge test data. The soil parameters were evaluated based on laboratory test results. The seismic response data from 20 g centrifuge tests were analyzed, and the results were generally consistent with the results of centrifuge model tests. In particular, the effective stress model showed a reasonable ability to reproduce the varying degrees of uplift displacement depending on the geotechnical conditions of trench soils adjacent to the hollow cylinder structures buried in shallow ground. 相似文献
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地铁车站的地震液化上浮是地下结构常见的灾害之一,对处于液化场地的地铁车站需增加抗液化及抗浮措施。通过数值分析的方法对比分析了抗拔桩和隔离墙2种抗浮措施的作用机理及作用效果,研究了车站的上浮位移、地表变形和周围土体超孔隙水压比等动力响应。结果表明:设置抗拔桩可提供抗拔力,隔离墙可有效阻挡液化土的流动,因此地铁车站的上浮位移明显减小;抗拔桩的长度进入非液化土层时抗浮效果最佳;隔离墙的抗浮效果随着与车站主体的距离增加而减弱。通过该项研究,可为液化场地中地铁车站的抗浮设计提供一定的理论参考。 相似文献