【作者】 Ammar A.M.Shubber（夏伯）；

【导师】 刘学毅；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2009， 博士

【摘要】 随着铁路朝着长大、高速、重载发展,轨道领域也取得了长足进步。无砟轨道在高速铁路建设和运营中有诸多优点,比如稳定性好,养护维修量小,因而被广泛地应用于世界各地的高速铁路上。在综合考虑了国内外相关领域情况的基础上,通过理论分析和实验研究,建立了高速铁路无砟轨道的分析模型和计算方法。主要工作和结论如下：1.建立高速动载作用下的无砟轨道计算模型和仿真方法为明确影响高速动荷载条件下轨道动力学特性的主要因素,研究并比较了一系列不同的模型对列车动荷载的响应。在模型的参数方面,主要考虑了路基结构、路基和橡胶垫板的阻尼,并考虑了由于轨枕点支承导致的轨道空间几何不连续所引起的轨道-路基相互作用。基于弹性地基上的梁-板模型,建立了轨道的仿真模型,分析其动力学特性。钢轨采用欧拉梁,承载层用弹性薄壳层模拟,扣件、CA砂浆和路基均采用弹簧阻尼器模拟,用有限单元方法进行建模。编制了仿真模型的计算程序,并用已有的结论进行了验证。总结并讨论了高速铁路轨道在动荷载作用下的特性和规律。计算给出了高速移动荷载下的轨道动力响应,并研究了列车速度对动力响应的影响。结果表明,随着列车速度的提高,CA砂浆层的动弯应力和路基中的动应力均随之增长。分析了由于高速列车对地面的激振引起的弹性附加牵引力。弹性附加牵引力的大小与空气阻力引起的附加牵引力大小相当甚至更大。因此,在高速条件下,弹性附加牵引力的大小作为能量损失的根源之一,是一项重要的设计准则。2.建立轮轨接触不平顺作用下的垂向力与变形计算模型和仿真方法建立了高速铁路轨道不平顺导致的轮轨相互作用模型,并进行了计算、模拟分析以及深入探讨。基于线路垂向相互作用关系,用非线性有限元方法建立了轨道的整体模型,并编制了计算程序。将理论计算结果与遂渝线无砟轨道试验段现场测试结果进行了比较,发现两者在很大程度上是一致的,计算和模拟分析所采用的方法是正确、合理的。3.研究高速动载作用下刚度和阻尼对轨道性能的影响对刚度和阻尼的影响效果的研究表明,路基刚度主要影响底座板加速度,但影响较小。增大路基和橡胶垫板的阻尼能降低临界速度下的轨道振动的放大效应,同时也会导致弹性牵引力的明显增加。因而阻尼的增加会造成相当大的能量损失,这对高速交通是不利的。4.研究高速动载作用下列车临界速度和路基状况对无砟轨道性能的影响研究了恒定移动荷载下路基分层对轨道动力响应的影响,结果表明这种影响是相当明显的。结果显示,列车的临界速度受轨道和列车的自重恒载的限制,且大小接近于轨道周围地面下的瑞利波速度。这个结论无论是对埋入式的无砟轨道还是对普通的有砟轨道都适用。临界速度的大小主要取决于路基土的力学特性和含水量。松软土的临界速度大概在150-300 km／h之间,而现代的高速机车是可以达到这个速度的。因此必须仔细探讨在这种情况下会出现什么问题。路基土层的厚度和力学性能的变化能够改变临界速度的大小,降低或增大轨道动力响应的扩大效应,改变轨道响应的型式。5.提出一种适用于国内高速铁路轨道的检测和养护维修技术讨论了世界各国广泛采用的检测和养护维修技术,在此基础上提出了适用于中国高速铁路无砟轨道的技术。这些技术可能对既有线和客运专线的运营、养护维修以及改建大有裨益。更多还原

【Abstract】 Railway tracks have been improved to keep pace with the improvement of railway such as extension, speed-up and high density operation of vehicles. Ballastless track is widely used nowadays in high speed railways especially in China, Europe and Japan due to its many advantages for the constructions and operations of high speed railway lines infrastructures; such as its high stability and low maintenance.In this thesis, based on the comprehensive research of relative fields at China and abroad, an analytical model and calculation method for a slab track railway under high speed moving load was built up by means of the theoretical analysis and experimental study. The research work and main conclusions are divided into the following areas:1. Establishing the computing model and simulation method for dynamic analysis of slab track under high speed moving loadIn this thesis, the steady-state response of various models for railway track to a set of uniformly moving constant loads (train) have been investigated to reveal the factors which are of primary importance in the dynamics of high speed ballastless track railway and to compare different track models.Concerning the parametric analysis of the models, the main attention has been paid to the configuration of the ground sub-soil, damping in the ground, in the pads, and the effect of the spatially discontinuous rail-ground interaction that is caused by the sleepers.Based on the beam shell model on elastic foundation, a slab track simulation model was established. The dynamic characteristics of the slab track were analyzed. The rail was simulated by Euler beam. Bearing layers were simulated by elastic thin shell. The elasticity of the fastener, CA mortar and subgrade were simulated by spring combination. The model was actualized using FEM. A calculating program of the simulation method was coded and verified by some known results.The characteristics and rule of high speed ballastless track railway under dynamic loading were summarized and discussed.The dynamic responses of ballastless track under high speed moving load were given, and the effect of vehicle velocity on the track dynamic responses was studied. The results showed that the dynamic bending stress of CA mortar and dynamic stress of subgrade increases with the increase of vehicle velocity.Elastic drag experienced by a high speed train due to excitation of ground vibrations has been analyzed. It has been shown that the elastic drag can be comparable and can exceed the aerodynamic drag (starting from the velocities close to the Rayleigh wave velocity). Thus, the elastic drag is an important design criterion for high speed trains to be accounted for as a source of perceptible energy loss.2. Establishing the computing model and simulation method for the vertical forces and deformations rule due to irregularities on wheel/rail of slab track under high speed moving loadIn this thesis, the interaction between rail-wheel for high speed railway slab track with irregularities were modeled, calculated, simulated and researched in detail.Based on the vertical interaction relations, an integral FE model of slab track with a computing program was developed using the non-linear FEM. A comparison between site test results of Suining-Chongqing test line and theoretical calculated results was discussed, which primarily showed a significance correlation, proposing that the calculating method and simulation method can be considered correct and reasonable.3. Studying the effect of the stiffness and damping on the behavior of the slab track under high speed moving loadThe study of the effect of the stiffness and damping in the considered models has shown that, the subgrade stiffness mainly influences the acceleration of the base slab, but the degree is relatively small. Although the increase of the damping (in the subsoil, and in the pads) generally reduces the amplification of the track vibrations at the critical velocity, it leads also to a substantial increase of the elastic drag in the sub-critical case. That is why the increase in the damping can cost a perceptible energy loss, which is unfavorable for high speed transportation.4. Studying the effect of critical velocity of the train and sub-soil conditions on the behavior of the slab track under high speed moving loadThe investigation of the influence of ground stratification on the dynamic response of the railway track to a constant moving load has demonstrated that the soil stratification strongly affects the dynamic response of the railway track.The results showed that the critical velocity of the train that is conditioned by its dead weight (constant load) is approximately equal to the Rayleigh wave speed in the ground surrounding the railway track. This result is as valid for a homogeneous (embedded) track as for an inhomogeneous (conventional) track. The magnitude of the critical velocity depends mainly upon the physical properties and saturation of the sub-soil. If the ground is soft, the value of the critical velocity, varying from 150 to 300 km/h, is attainable by contemporary high speed trains. This implies that a careful study is necessary of what would happen if such a regime of motion were to occur.Variations in depth of the soil layers and in their physical properties can result in; shifting and introducing new critical velocities of the train; reducing or increasing the dynamic amplification of the track response; and scaling the spatial pattern of the rail response.5. Proposed an inspection and maintenance technique to be used for high speed slab track railway in ChinaIn this thesis, some inspections and maintenance techniques world wide existed and used were discussed. Based on these existed techniques and experts, the proposed method was advised to be implemented and used in Chinese high speed ballastless track railway systems, which might be helpful in the operation, management and rehabitation of the existing and the new PDLs high speed railway in China.更多还原