城市轨道交通系统节能措施研究

轨道交通的建设是实现城市交通节能的重要手段。轨道交通系统自身的节能工作也十分重要。本文分别从轨道交通的规划设计、施工建设以及运营管理阶段,提出轨道交通的节能措施。     

采用无缝线路的津滨轻轨高架桥梁下部结构设计研究

介绍在津滨轻轨桥梁下部结构设计中 ,由于考虑了桥上无缝线路的纵向力 ,出现了新的问题。通过实例计算 ,分析各种不同荷载组合的计算结果 ,提出考虑无缝线路纵向力后桥下部结构设计的控制工况及应注意的问题     

Nonlinear three-dimensional wagon-track model for the investigation of rail corrugation initiation on curved track

A nonlinear wagon-track model on curved track has been developed to characterize rail corrugation formation due to self-excitation of the wheel-rail stick-slip process. In this model, wagon movements were described using up to 78 degrees of freedom (DOFs) to model a three-piece freight bogie. Innovatively, the wheelset movements are described using nine DOFs, including torsional and bending modes about the longitudinal and vertical directions. The track modelling is considered as a one-layer structure (two rail beams on discrete spring and damper elements). The wheel sliding after creepage saturation is considered in the wheel-rail interface modelling. Simulation of a case study shows that the frequencies of the wheel stick-slip process are composed of the basic frequency, which might come from the combined effect of sleeper-passing frequency and one-third of the combined torsional and bending frequency of the wheelset, and the double and triple basic frequencies, which form the wavelengths of rail corrugation at different situations.     

北京地下直径线前三门隧道上跨地铁联络通道及电力隧道设计方案研究

为解决在特定的城市地下空间新建隧道施工影响既有地下结构安全的问题,以北京地下直径线前三门隧道上跨既有隧道工程为研究对象,提出"隔离桩保护,分步开挖"设计方案,模拟隧道分步开挖过程,计算隧道施工过程中联络通道的位移值。主要结论如下:隧道采用相应的保护措施和分步施工法是可行的,施工不会影响联络通道及电力隧道的结构性安全。     

新形势下的基础设施投融资改革初探——城市轨道TOD实践带来的启示

基础设施项目建设对国民经济的拉动效应显而易见,轨道交通建设给城市发展带来更多的机遇和挑战。地方政府在轨道建设前期如何前瞻规划、统筹安排和有效整合沿线资源,探索适合的建设模式对实现项目的可持续发展至关重要。以深圳地铁6号线为例,借鉴香港"轨道+物业"轨道发展经验,通过优化轨道交通沿线土地利用布局和开发强度,实践轨道交通TOD开发模式。阐述城轨TOD与香港地铁"轨道+物业"的理念,分析香港地铁"轨道+物业"模式在大陆应用存在的问题,介绍"轨道+物业"理念在深圳地铁6号线规划研究中的应用成果,将"轨道+物业"的模式与传统模式进行对比,总结城市轨道交通TOD模式成功实施的重要条件。最后对国内城轨TOD成功实施提出一些建议:创新城市轨道交通沿线土地出让和储备机制,探索城市轨道交通和城市空间规划接驳机制,完善城市轨道交通管理体制机制,完善政策及技术规范支撑,加强法规制度保障等。     

钢箱梁U肋嵌补段疲劳开裂机理与养护措施研究

某大型悬索桥为主跨1650 m的两跨连续钢箱梁悬索桥,加劲梁采用扁平流线型分离式双箱。近2年在正交异性板钢箱梁顶板U肋嵌补段发现焊缝开裂状况,为研究及处治该病害,采用大型有限元程序ANAYS进行局部仿真计算,分析焊缝开裂后的应力分布规律、影响范围。结果表明:重车轮压的疲劳荷载、施工焊接质量等是嵌补段焊缝开裂的主要原因;钢箱梁顶板U肋嵌补段焊缝开裂会对邻近结构抗力产生影响,U肋嵌补段开裂使相邻U肋嵌补段焊缝应力增加11.8%,使U肋与顶板之间焊缝主拉应力增加57%,使邻近位置的横隔板弧形缺口主拉应力增加6%。根据分析结果建议尽早处治焊缝开裂问题,短期养护措施推荐在低应力区打止裂孔和设置临时支撑架,长期养护措施建议刨去已开裂焊缝后补焊、嵌补段整体切割后补焊和改用高强度螺栓连接方式。     

Modelling of wheels and rail discontinuities in dynamic wheel-rail contact analysis

A classification of wheel-rail contact is given. Difference is made between modelling of a running wheel with continuous single-point-contact, as is common practice in wheel-rail contact analysis, and a wheel with transient double- or multi-point-contact, which may occur for rail irregularities with curvatures larger than that of the wheel circumference. It is shown that application of the first model for these irregularities will strongly underestimate the contact forces as it does not describe occurring mechanisms correctly. Further, it is shown that in principle it is not possible to describe the second type of contact fully correct with a lumped wheel model. Both wheel models are formulated mathematically for some basic contact cases. Afterwards, results are applied to a linear track model. Analytical closed-form solutions are found in the frequency domain for arbitrary type of contact and numerically transformed to the time domain. Finally, the necessity is shown to avoid situations where transient multiple-point-contact may occur (like rail joints) in practice.     

Passenger railway reform in the last 20 years - European experience reconsidered

It is about 20 years since the rail reform process in Europe began with the separation of infrastructure from operations in Sweden. This paper reviews the entire process, examining the objectives of reform, the different models adopted, and the key elements of separation of infrastructure from operations, competition both through open access and franchising and regulation and infrastructure charging. It is concluded that separation of infrastructure from operations involves costs, but is the most effective way of achieving within mode competition. Where operations do not greatly overlap and open access passenger and freight are unimportant, leasing infrastructure to passenger franchisees may be effective, but the model of vertical integration as separate subsidiaries within a holding company structure makes it difficult to ensure a level playing field for new entrants and is only effective where the vertically integrated operator remains dominant.     

Light Rail Rapid Transit systems for more sustainable ground accessibility of airports

This paper investigates the potential of Light Rail Rapid Transit (LRRT) to mitigate the environmental and social burden of ground access systems of an airport. This implies, on the one hand, LRRT's capability in mitigating externalities in terms of noise, air pollution/climate change, traffic incidents/accidents and congestion of airport ground access systems and, on the other, the provision of sufficient capacity to accommodate generally increasing volumes of both air passenger and airport employee demand by connecting the airport to its core catchment area. A methodology for assessing the capability of LRRT operating as an airport ground access system is developed. This methodology consists of models to analyze and predict demand and capacity for an LRRT system and models to quantify the externalities of particular airport ground access systems as well as assessing their prospective savings thanks to the introduction of an LRRT system. The methodology is applied to a large European airport – Amsterdam Schiphol (the Netherlands) – using a ‘what-if?’ scenario approach.     

Wheel-rail contact models for vehicle system dynamics including multi-point contact

Advanced modelling of rail vehicle dynamics requires realistic solutions of contact problems for wheels and rails that are able to describe contact singularities, encountered for wheels and rails. The basic singularities demonstrate themselves as double and multiple contact patches. The solutions of the contact problems have to be known practically in each step of the numerical integration of the differential equations of the model. The existing fast, approximate methods of solution to achieve this goal have been outlined. One way to do this is to replace a multi-point contact by a set of ellipses. The other methods are based on so-called virtual penetration. They allow calculating the non-elliptical, multiple contact patches and creep forces online, during integration of the model. This allows nearly real-time simulations. The methods are valid and applicable for so-called quasi-Hertzian cases, when the contact conditions do not deviate much from the assumptions of the Hertz theory. It is believed that it is worthwhile to use them in other cases too.