斜拉桥上无缝线路纵向相互作用理论及试验研究

运用梁轨纵向相互作用机理,建立斜拉桥上无缝线路纵向力计算模型,以一座铁路常用双塔钢桁斜拉桥为例,对斜拉桥上无缝线路纵向相互作用规律进行理论和试验研究。分析结果表明:在主桥左右两端各铺设一组单向伸缩调节器,主桥上钢轨纵向力可得到有效的控制,现场试验测试的桥面纵向位移及钢轨伸缩力分布规律与理论计算基本相同,所建立模型可用于斜拉桥上无缝线路纵向相互作用分析;钢轨挠曲力计算时,可在斜拉桥主跨及其邻跨上布置荷载,且不必考虑列车入桥方向的变化;钢轨伸缩调节器可有效减弱列车制动荷载下的梁轨相互约束作用,减小线路受力变形。     

Modelling,simulation and evaluation of ground vibration caused by rail vehicles*

ABSTRACT

There is a great need to develop rail networks over long distances and within cities as more sustainable transport options. However, noise and vibration are seen as a negative environmental consequence. Compared with airborne noise, the related problem of ground vibration is much more complex. The properties of the ground vary significantly from one location to another. There is no common assessment criterion or measurement quantity and no equivalent to the noise maps. Ground-borne vibration is transmitted into buildings and perceived either as feelable whole-body vibration or as low frequency noise; it can also affect sensitive equipment but it is generally at a level that is too low to cause structural or cosmetic damage to buildings. A review is given of evaluation criteria for both feelable vibration and ground-borne noise, empirical and numerical prediction methods, the main vehicle and track parameters that can affect the vibration levels and a range of possible mitigation methods.     

Train–track–bridge dynamic interaction: a state-of-the-art review

ABSTRACT

Train–track–bridge dynamic interaction is a fundamental concern in the field of railway engineering, which plays an extremely important role in the optimal design of railway bridges, especially in high-speed railways and heavy-haul railways. This paper systematically presents a state-of-the-art review of train–track–bridge dynamic interaction. The evolution process of train–bridge dynamic interaction model is described briefly, from the simplest moving constant force model to the sophisticated train–track–bridge dynamic interaction model (TTBDIM). The modelling methodology of the key elements in the TTBDIM is systematically reviewed, including the train, the track, the bridge, the wheel–rail contact, the track–bridge interaction, the system excitation and the solution algorithm. The significance of detailed track modelling in the whole system is highlighted. The experimental research and filed test focusing on modelling validation, safety assessment and long-term performance investigation of the train–track–bridge system are briefly presented. The practical applications of train–track–bridge dynamic interaction theory are comprehensively discussed in terms of the system dynamic performance evaluation, the system safety assessment and train-induced environmental vibration and noise prediction. The guidance is provided on further improvement of the train–track–bridge dynamic interaction model and the challenging research topics in the future.     

Stochastic Monte Carlo simulations of the pantograph–catenary dynamic interaction to allow for uncertainties introduced during catenary installation

The simulation of the pantograph–catenary dynamic interaction is at present mainly based on deterministic approaches. However, any errors made during the catenary stringing process are sources of variability that can affect the dynamic performance of the system. In this paper, we analyse the influence of dropper length, dropper spacing and support height errors on the current collection quality by applying a classic Monte Carlo method to obtain the probability density functions of several output quantities. The effects of installation errors are also studied for a range of train speeds. Finally, the pre-sag that, on average, produces the best behaviour of the system is identified, allowing for the uncertainty in the catenary installation. The results obtained show the convenience to consider variability in pantograph–catenary dynamic simulations.     

客运专线拱桥承台设计方法的探讨

为解决客运专线拱桥承台设计无明确铁路规范可依这一问题,通过建立桩-土-承台结构相互作用模型的方法,阐述桩-土-承台结构在上部结构作用下如何计算承台的应力和配筋,通过与已有规范方法比较,论证了桩-土-承台相互作用模型的配筋结果更加安全,为拱桥承台设计提供了有益的参考。     

Active control strategy on a catenary–pantograph validated model

Dynamic simulation methods have become essential in the design process and control of the catenary–pantograph system, overall since high-speed trains and interoperability criteria are getting very trendy. This paper presents an original hardware-in-the-loop (HIL) strategy aimed at integrating a multicriteria active control within the catenary–pantograph dynamic interaction. The relevance of HIL control systems applied in the frame of the pantograph is undoubtedly increasing due to the recent and more demanding requirements for high-speed railway systems. Since the loss of contact between the catenary and the pantograph leads to arcing and electrical wear, and too high contact forces cause mechanical wear of both the catenary wires and the strips of the pantograph, not only prescribed but also economic and performance criteria ratify such a relevance. Different configurations of the proportional-integral-derivative (PID) controller are proposed and applied to two different plant systems. Since this paper is mainly focused on the control strategy, both plant systems are simulation models though the methodology is suitable for a laboratory bench. The strategy of control involves a multicriteria optimisation of the contact force and the consumption of the energy supplied by the control force, a genetic algorithm has been applied for this purpose. Thus, the PID controller is fitted according to these conflicting objectives and tested within a nonlinear lumped model and a nonlinear finite element model, being the last one validated against the European Standard EN 50318. Finally, certain tests have been accomplished in order to analyse the robustness of the control strategy. Particularly, the relevance or the plant simulation, the running speed and the instrumentation time delay are studied in this paper.     

线路纵向阻力形式对桥上无缝线路计算影响

为了研究线路纵向阻力形式对桥上无缝线路纵向力的影响,基于梁轨相互作用原理,采用有限元方法建立了线-桥-墩一体化计算模型,以多跨简支梁为例,分析了常阻力、双线性和幂指数型等不同形式的线路阻力对计算桥上无缝线路时的影响。计算结果表明:常量阻力下计算得到的钢轨伸缩力较双线性及幂指数型阻力要小,且随温度跨度的增加双线性和幂指数型计算结果越来越接近,而常量阻力与两者差别逐渐增大;计算钢轨制动力时,常量阻力计算结果要小得多,且梁轨相对位移较大,已超出我国检算标准;不同钢轨降温幅度下,双线性和幂指数型阻力计算的钢轨断缝值基本相同,但却远小于常量阻力,且钢轨降温幅度越大,差别越大。由此可知,应重视线路阻力形式的选取,尽量由实际测试数据进行拟合,使其能模拟真实的现场情况。     

考虑驾驶人特性的一主多从混合博弈容错控制

为保证线控底盘电动汽车在遭遇执行器失效时的稳定性，并考虑人-车交互行为，提出了以驾驶人为领导者的一主多从（Single-leader-multiple-follower，SLMF）混合博弈容错控制框架。为实现驾驶人-车辆的交互控制，首先建立了两者的耦合模型。其次，将驾驶人及5个底盘子系统即主动前轮转向（Active Front Steering，AFS）系统和4个轮毂电机建模为博弈中的6个参与者，基于Stackelberg主从博弈与多人合作博弈设计了SLMF混合博弈控制框架。考虑驾驶人具有优先控制权限及执行器对驾驶人行为的补偿作用，基于Stackelberg博弈理论建立了驾驶人与底盘子系统的主从博弈模型，其中驾驶人作为领导者通过感知跟随者的行为做出转向决策，而5个底盘子系统被建模为跟随者。由于跟随者追求共同的横向稳定控制目标，因此基于合作博弈理论建立了合作模型，并对领导者的转向策略做出最优响应。最后，为研究跟随者之间追求不同目标导致不合作时的控制效果，设计了非合作Nash博弈与Stackelberg博弈相结合的混合博弈为对比方法，通过实时硬件在环测试验证并对比了2种方法。结果表明：针对不同风格的驾驶人，所设计的方法可以保证遭遇执行器卡死失效车辆的稳定性。与不合作的情况相比，2种不同风格的驾驶人驾驶的车辆在底盘子系统合作时，车辆稳定性分别提升了54.62%和53.78%，驾驶人工作负荷分别降低了31.79%和36.07%。     

PERSISTENT CURRENT IN A ONE-DIMENSIONAL MESOSCOPIC RING WITH ELECTRON-PHONON INTERACTION IN THE LATTICE MODEL

IntroductionSince the pioneering work of Büttiker etal[1,2 ] ,the problem of persistentcurrent in a meso-scopic ring has attracted much recent atten-tion[3～ 6] . In a normal- metal ring threaded by amagnetic flux,a persistent current exists as longas the phase coherence of electron is pre-served[1,2 ,4 ] . With the gauge transformation,thevector potential can be removed from Schrodingerequation with a modified boundary conditionψn(x L ) =exp(2πi/0 )ψn(x) ,where0 =h/e is theflux q…     

地震作用下高桩承台桥梁结构工程简化模型的研究与分析

目前考虑桩土相互作用的结构抗震分析中常采用Penzien模型,Penzien模型虽然比较简单,但在实际工程计算中仍然很繁琐。讨论高桩承台结构工程简化模型的参数确定方法,并用Penzien模型对其进行校核,结果表明,工程简化模型计算上部结构的地震响应有着一定的适用性。