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Model testing in laboratory, as an effective alternative to field measurement, provides valuable data to understand railway׳s dynamic behaviors under train moving loads. This paper presents comprehensive experimental results on track vibration and soil response of a ballastless high-speed railway from a full-scale model testing with simulated train moving loads at various speeds. A portion of a realistic ballastless railway comprising slab track, roadbed, subgrade, and subsoil was constructed in a larger steel box. A computer-controlled sequential loading system was developed to generate equivalent vertical loadings at the track structure for simulating the dynamic excitations due to train׳s movements. Comparisons with the field measurements show that the proposed model testing can accurately reproduce dynamic behaviors of the track structure and underlying soils under train moving loads. The attenuation characteristics of dynamic soil stresses in a ballastless slab track is found to have distinct differences from that in a ballasted track. The model testing results provide better understanding of the influence of dynamic soil–structure interaction and train speed on the response of track structure and soils. 相似文献
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Piled embankments, which offer many advantages, are increasingly popular in construction of high-speed railways in China. Although the performance of piled embankment under static loading is well-known, the behavior under the dynamic train load of a high-speed railway is not yet understood. In light of this, a heavily instrumented piled embankment model was set up, and a model test was carried out, in which a servo-hydraulic actuator outputting M-shaped waves was adopted to simulate the process of a running train. Earth pressure, settlement, strain in the geogrid and pile and excess pore water pressure were measured. The results show that the soil arching height under the dynamic train load of a high-speed railway is shorter than under static loading. The growth trend for accumulated settlement slowed down after long-term vibration although there was still a tendency for it to increase. Accumulated geogrid strain has an increasing tendency after long-term vibration. The closer the embankment edge, the greater the geogrid strain over the subsoil. Strains in the pile were smaller under dynamic train loads, and their distribution was different from that under static loading. At the same elevation, excess pore water pressure under the track slab was greater than that under the embankment shoulder. 相似文献
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为研究高速铁路路堤中WIB(波阻板)的减隔振效果,构建了简易的铁路路堤原理性试验模型,获得了在WIB底面与路堤顶面垂直间距不同时、在路堤面上的简谐荷载作用下引起的振动波在模型表面的传播衰减规律,分析了铁路路基中WIB底面与路堤顶面垂直间距不同时的减隔振效果;构建了高速铁路路基三维动力数值仿真分析模型,并进行对比分析,验证了模型试验的合理性。结果表明:在高速铁路路堤的基床底层中设置WIB,越靠近路堤顶面,减隔振效果越好;在基床底层的顶面设置WIB的减隔振效果优于在基床表层设置WIB。 相似文献
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Recent advances in railway-induced ground vibrations showed that the track/soil interaction plays an important role in the low frequency range. This paper contributes to the numerical analysis of train/track/foundation dynamics by presenting the accuracy of a coupled lumped mass (CLM) model devoted to the railway foundations and to the track/soil coupling. Following a summary of the background and the advantages of the CLM model, the coupling strategy is quantified through two application cases. Firstly, the dynamic track deflection is calculated for different railway lines considering various degrees of complexities of foundations. Then, the foundation responses are compared depending on whether detailed coupling is introduced or not. The benefit of the proposed model is emphasized by presenting free-field ground vibration responses generated by a tram and a high-speed train, obtained by a revisited two-step prediction model developed by the authors. 相似文献
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Dynamic response of high-speed ballasted railway tracks: 3D periodic model and in situ measurements 总被引：2，自引：0，他引：2
A three-dimensional (3D) model for the soil–railway track system is proposed. It is based on a geometrical periodic hypothesis. The dynamic soil–structure interaction is taken into account. This representation is used for the case of a ballasted railway track subjected to high-speed moving loads and a new formulation of dynamic responses of the system is proposed. Moreover, recent in situ measurements performed in a high-speed line of the North of France are presented. Lateral and vertical accelerations in several locations of the railway track have been measured and the periodic model is confronted with these records. 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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传统路基动模量法大都进行单路基抗震性能分析,缺乏复合路基抗震性能分析,存在较高的偏差。对广州市轨道交通二十一号线工程路基抗震性进行测试,分析该地地质条件后,通过标准贯入实验法判断原始路基土质液化情况,使用瑞典条分法测试原始路基的抗震性能,判别出该路基液化土层滑动安全系数低、抗震稳定性差,应对其进行复合路基加固。通过圆弧滑动法对加固后的复合路基中碎石桩桩网结构路基以及CFG桩桩网结构路基进行抗震性测试。实验结果表明,所提方法抗干扰性能强且测试结果精度高。 相似文献
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修建在纵向不均质地层中的地铁隧道,由于列车循环荷载的作用,会导致隧道下部的土体产生不均匀沉降,对既有隧道产生不利的影响。针对这一问题,提出考虑隧道剪切效应的地基不均匀沉降对既有隧道竖向变形影响的解析解。既有隧道简化为搁置在Winkler地基上的Timoshenko梁,通过两阶段分析法,分析下卧地层不均匀沉降引起的隧道响应。首先确定列车荷载引起的动偏应力,并运用土层的力学指标计算出静偏应力和破坏偏应力。然后运用累积应变的经验公式计算出隧道下部土体的累计沉降,将土体的沉降转化为力施加在隧道上。基于Timoshenko梁理论,建立考虑隧道剪切效应的隧道竖向变形微分方程,求解得到隧道变形的解析解,进一步可以得到隧道的弯矩、剪力、转角、错台。 相似文献
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为研究G6京藏高速兰州—海石湾段红层路基填料导致的沉降问题,建立二自由度路基路面耦合离散元模型。通过迭代运算,得到各层材料的细观参数,编写Fish函数,用冲击荷载及半正弦荷载模拟交通荷载作用,在此基础上分析荷载作用下路基路面各层颗粒的位移和应力时程曲线。研究表明：基层与红层填料交界面处出现位移分层现象,基层受水平拉应力作用,是裂缝发展的高风险区,在公路运营过程中应定期重点监测该区域裂缝的发生。PFC模型实现了路基土体及路面结构层在离散元软件中协同变形的耦合,为不良路基地区道路的病害问题及沉降变形计算提供研究思路,为该地区后续的路基病害整治奠定理论基础。 相似文献
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建立精细化的足尺轨道-路基-地基耦合系统非线性数值分析模型,考虑岩土材料的非线性应力-应变关系、路基填筑完成后的静应力状态对其后动力计算的影响、底座板底面与路基基床表层表面之间的动力相互作用,模拟轨道与路基系统的建造过程和与8辆编组动车组轮对相对应的荷载以350 km/h的速度的移动过程。结果显示,以实体单元模拟钢轨能获得更符合事实的钢轨空间振动响应,比采用梁单元更具优势;路基各层底面的动位移具有随时间和空间变化的特征;沿路基断面横向,不同时刻的竖向动位移在轨道板宽度范围内的最大波动值约0.04 mm,可认为均匀分布;沿深度方向,竖向动位移在不同时刻的分布相似,按照指数函数衰减,最大值约为0.8 mm,小于我国高速铁路3.5 mm的控制标准;沿线路纵向,竖向动位移峰值出现的位置与该时刻移动荷载所处的空间位置对应,在同一深度条件下,不同时刻的竖向动位移分布形态相似;基床底层底面以上,同一转向架上前后轮对对应的荷载引起的竖向动位移具有可观的叠加效应。 相似文献
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《Soil Dynamics and Earthquake Engineering》2012,32(12):1711-1723
This paper presents a coupled lumped mass model (CLM model) for the vertical dynamic coupling of railway track through the soil. The well-known Winkler model and its extensions are analysed and fitted on the result obtained numerically with a finite–infinite element model in order to validate the approach in a preliminary step. A mass–spring–damper system with frequency independent parameters is then proposed for the interaction between the foundations, representing the contact area of the track with the soil. The frequency range of track–soil coupling is typically under 100 Hz. Analytical expressions are derived for calibrating the system model with homogeneous and layered half-spaces. Numerical examples are derived, with emphasis on soil stiffness and layering. The dynamic analysis of a track on various foundation models is compared with a complete track–soil model, showing that the proposed CLM model captures the dynamic interaction of the track with the soil and is reliable to predict the vertical track deflection and the reaction forces acting on the soil surface. 相似文献
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G. Kouroussis G. Gazetas I. Anastasopoulos C. Conti O. Verlinden 《Soil Dynamics and Earthquake Engineering》2011
This paper presents a coupled lumped mass model (CLM model) for the vertical dynamic coupling of railway track through the soil. The well-known Winkler model and its extensions are analysed and fitted on the result obtained numerically with a finite–infinite element model in order to validate the approach in a preliminary step. A mass–spring–damper system with frequency independent parameters is then proposed for the interaction between the foundations, representing the contact area of the track with the soil. The frequency range of track–soil coupling is typically under 100 Hz. Analytical expressions are derived for calibrating the system model with homogeneous and layered half-spaces. Numerical examples are derived, with emphasis on soil stiffness and layering. The dynamic analysis of a track on various foundation models is compared with a complete track–soil model, showing that the proposed CLM model captures the dynamic interaction of the track with the soil and is reliable to predict the vertical track deflection and the reaction forces acting on the soil surface. 相似文献
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我国众多铁路干线分布于深季节冻土地区。铁路路基土层的冻融状态随着季节的交替变化而改变,相应的列车行驶时引起的路基动应力分布也有所不同。考虑路基土体的参振效应,通过改进车辆-轨道-路基垂向耦合动力学模型获取不同季节列车行驶振动荷载时程,进而通过动力有限元数值模拟方法,研究季节变化对列车行驶引起的路基动应力分布规律的影响。研究表明:路基土中的动应力幅值及其沿路基深度的分布规律与该时期路基土的冻融状态密切相关,基于此结论,提出深季节冻土地区不同季节铁路冻土下限范围内路基动应力的简化计算方法。该研究对于优化季节性冻土地区铁路路基设计方法,完善路基长期动力稳定性能评价方法等具有重要意义。 相似文献
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针对巴准重载铁路高路堤典型断面,采用三维非线性有限元与经验公式相结合的方法,建立了可考虑列车-轨道动力相互作用的重载列车振动荷载引起的高路堤路基累积变形计算方法。首先,基于列车-轨道垂向耦合动力系统理论,建立重载列车-轨道动力耦合体系数值模型,并实施重载列车-轨道耦合系统动力分析;其次,建立轨枕-道床-路基-场地动力系统的三维有限元模型,并输入求解的列车振动荷载作为外部激励;最后,采用Li和Selig推荐的改进土体累积变形预测模型并结合有限元分析结果,分析了未加固和应用土工格栅加固的高路堤路基累积变形的基本特征与规律。发现土工格栅可显著减小路基的动力累积变形作用。 相似文献
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This paper has two main purposes. One is to present and analyse soil and structural vibration data obtained experimentally during certification testing of the high-speed train line between Córdoba and Málaga (Spain) that was opened on December 2007. The second is to show the capabilities of a three-dimensional boundary element method (BEM)/finite element method (FEM) numerical approach for the analysis of train induced vibrations. The model can represent local soil conditions, discontinuities such as underpasses, as well as structures placed next to the rail track. Vibrations in those structures can be computed taking into account, in a rigorous way, dynamic soil–structure interaction and local soil properties. Experimental and numerical results at several points near the track are compared. Results for an overhead contact support structure are also evaluated. The comparison of numerically predicted and recorded results shows that the model is reliable for predicting the amplitude of vibrations produced in the soil and nearby structures by high-speed trains. 相似文献
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Cement-mixed piles, as countermeasure against liquefaction of silt and sand ground, can improve the shear strength and bearing capacity of foundation soil, meaning cement-mixed piles are capable of resisting displacement when an earthquake happens. However, investigations of cement-mixed piles by experimental methods such as the shaking table test is few and far between. It is especially true for the seismic performance of cement-mixed piles in liquefiable railway foundations in high seismic intensity regions. To this end, a cross-section of the Yuxi-Mengzi railway was selected as the prototype and studied by the shaking table test in this study. The results showed that composite foundation of cement-mixed piles was not liquefied when the seismic acceleration was lower than 0.30g. In the process of acceleration increasing from 0.30g at 2Hz to 0.60g at 3Hz, the upper middle silt outside slope toe was partly liquefied. The foundation soil under the shoulders and center of subgrade was far from the initial liquefaction criterion during the test. Cement-mixed piles can effectively reduce the embankment settlement and differential settlement. It can be concluded that, the design of cement-mixed piles can ensure the seismic performance of the subgrade, and satisfy the seismic design requirements of the Yuxi-Mengzi railway in areas of VⅢ degrees seismic fortification intensity. 相似文献
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This paper describes a laboratory model test carried out on high-density polyethylene (HDPE), small diameter pipes buried in trenches, which subjected to repeated loadings to simulate the vehicle loads. Deformation of the pipe was recorded at eight points on the circumference of the tested pipes to measure the radial deformations and detect cross-sectional pipe profiles. Also settlement of the soil surface during the test up to 1000 cycles of loadings was recorded, until its value become stable or the excessive settlement was happened. The parameters varied in the testing program include height of buried depth, relative density of the sand and intensity of stress on the soil surface. The influence of various repeated loads (with magnitude of 250, 400 and 550 kPa) at relative densities of 42%, 57% and 72% in different embedded depth of 1.5–3 times of pipe diameter were investigated. Based on the results, in medium and dense sand relative density, the pipe embedded in depth of 3.0D and 2.0D, respectively, mostly remained undamaged (the maximum value of VDS is less than 5%) and increased the safety of buried pipes under different magnitude of repeated loads. The records of the pipe deformation and settlement of the soil surface due to the repeated loads have been compared in different conditions. These values increase rapidly during the initial loading cycles by a rate decreasing significantly as the number of cycles increase. The influence of the first cycle was also found to be one of the main behavioral characteristics of buried pipes under repeated loads. The ratio of deformation of pipe at first cycle to last cycle changes from 0.60 to 0.85 in different of tests. Finally for the obtained results, a non-linear power model has been developed to estimate the vertical diametral strain of buried pipe and settlement of the soil surface based on the model test data. It should be noted that only one type of pipe and one type of sand are used in laboratory tests. 相似文献