高速铁路轮轨关系典型案例研究

针对高速铁路运营过程中出现的高速道岔直尖轨裂纹、弹条断裂、动车组构架横向加速度报警等典型案例进行研究,分析案例产生的原因,介绍采取的相应对策,阐明研究高速铁路轮轨关系的重要性。研究得出:应通过采取加强钢轨状态检查、加强钢轨养护以保持钢轨良好廓形;大力推广应用钢轨打磨新廓形;积极推广使用60N钢轨等措施改善高速铁路轮轨关系。该研究对进一步加强我国高速铁路轮轨关系维护、确保轮轨关系匹配良好,具有指导意义。     

��ͨ����������Ϣ����ϵͳ

交通气象智能信息服务系统是实现在互联网上更加方便、快捷、自动的搜索到用户所需要的信息的应用平台，该系统不同于现有的限制性搜索模式，首先结合分词系统，采用句型分析算法，并结合系统本身建立的信息检索规则库对用户的输入进行智能分析，然后通过平台内部建立的信息查询索引结构对相关信息进行综合，最终使用户得到更准确的信息。     

软弱夹层对土-结构动力相互作用的影响分析

针对某一桥墩与地基土层相互作用,采用通用有限元程序ANSYS,进行了二维动力有限元数值模拟计算,计算中均匀地基土体的本构模型采用ANSYS程序里的Drucker-Prager模型,通过EICentro地震波输入,对比分析了考虑软弱夹层对土—结构动力相互作用特性的影响。     

城市交通与土地利用互动机理研究

城市交通与土地利用之间存在着复杂的互动关系,研究二者的互动机理,对从根本上解决城市交通问题以及实现城市可持续发展具有重要的理论与现实意义。首先分析城市交通与土地利用的关系,指出二者之间存在相互依存、相互促进的互动关系;然后建立数学模型描述二者互动的方向及程度,从模型稳定性分析可以看出,当满足一定条件时,二者能够达到一种“互补共生”的稳定平衡状态;在此基础上,结合实例对模型进行仿真,验证了模型的稳定性条件;最后,基于二者的互动机理提出一些城市规划对策。     

Analysis of interaction factors between two piles

A rigorous analytical method is presented for calculating the interaction factor between two identical piles subjected to vertical loads. Following the technique proposed by Muki and Sternberg, the problem is decomposed into an extended soil mass and two fictitious piles characterized respectively by Young＇s modulus of the soil and that of the difference between the pile and soil. The unknown axial forces along fictitious piles are determined by solving a Fredholm integral equation of the second kind, which imposes the compatibility condition that the axial strains of the fictitious piles are equal to those corresponding to the centroidal axes of the extended soil. The real pile forces and displacements can subequally be calculated based on the determined fictitious pile forces, and finally, the validity of the proposed approach and desired pile interaction factors may be obtained. Results confirm the portray the influence of the governing parameters on the pile interaction.     

Assessment of uncertainty in the CFD simulation of the wave-induced loads on a vertical cylinder

The paper addresses different uncertainty analysis methods commonly used for uncertainty quantification in Computational Fluid Dynamics (CFD) studies and compares a constant Courant–Friedrichs–Lewy (CFL) number based approach for uncertainty estimation to the ITTC recommended grid and time-independent procedures. Four different uncertainty estimation procedures are presented and discussed. To compare their performance and better understand CFD related uncertainty quantification in wave load simulations on offshore structures, the methods are applied to a case study of the wave loads on a fixed vertical cylinder. The numerical or CFD wave tank is generated using the open-source CFD toolkit OpenFOAM. Uncertainty is assessed for the case study using four different uncertainty estimation procedures for verification and later, validation is attempted by comparing the CFD results with experiments. The study concludes that a constant CFL number based uncertainty study provides more stable results and is better suited for uncertainty estimation in CFD than the ITTC recommended individual grid and time step uncertainty study.     

Effects of Friends' Information Interaction on Travel Decisions

Many existing studies focus on the effects of traffic information from ATIS on travel choices. Research on the effect of friends' travel information on people's travel choice is uncommon, yet needed. In this paper, behavioral experiments are conducted to discuss what the effects of information interaction with friends can bring on individual travel decision behavior. The experimental results concluded that when the rate of friends' information interaction reaches 33.3%, the whole system is at an optimal level. Furthermore, users reach an optimum when the rate of friends' travel information interaction is 75%. The average time and cost per person is increasing when the whole system optimum transfers to the user optimum. Moreover, adjustments of departure time at the system optimum are more dispersed than at the user optimum, while travel choice changes are more concentrated.     

Modelling and validation of coupled high-speed maglev train-and-viaduct systems considering support flexibility

This study presents a more realistic modelling of the maglev-based high-speed railway line in Shanghai, China. Focus is placed on an accurate simulation of the two subsystems: the train subsystem including the magnets and the viaduct subsystem including the modular function units of the rails. The electromagnet force–air gap model with a proportional-derivative (PD) controller is adopted to simulate the interaction between the maglev train via its electromagnets and the viaduct via its modular function units. The flexibilities of the rails, girders, piers and associated elastic bearings are all considered in the modelling of the viaduct subsystem to investigate their effects on an interaction between the two subsystems. By applying the proposed model to the Shanghai maglev line, the essential characteristics of the coupled system can be duly captured. The accuracy and effectiveness of the proposed approach are then validated by comparing the computed dynamic responses and frequencies with the measurement results. It is confirmed that the proposed modelling with a detailed simulation of the magnets and modular function units can duly account for the dynamic interaction between the train and viaduct systems. Moreover, the effects of the inclusion of the flexibilities of the rails, girders and elastic supports to the response of the coupled system are respectively investigated, the results of which prove that their involvements are essential to the accurate prediction of the response of the coupled maglev train–viaduct system.     

基础与结构共同作用在虹桥枢纽中的应用分析

研究目的:针对虹桥综合交通枢纽结构体系复杂、柱底反力极不均匀、基础与结构刚度相差不大的实际情况,传统计算方法已不能反映结构的实际受力状态,特别是对上部结构影响很大,本文对基础与结构的共同作用分析方法与传统计算方法进行对比,分析结构和基础的计算结果及原因,以期找出适当的方法指导类似工程的设计。研究结论:对于基础与上部结构刚度差别不大,柱轴力极不均匀的结构,应采用考虑上部结构与基础的相互影响的共同作用方法进行分析。基础对结构的影响程度与基础、结构的相对刚度有关,基础刚度越大,影响越小。对于目前综合交通枢纽中大柱网加填充柱网的结构来说,基础的变形对上部结构的影响是不能忽略的。     

Influence of the aerodynamic forces on the pantograph–catenary system for high-speed trains

Most of the high-speed trains in operation today have the electrical power supply delivered through the pantograph–catenary system. The understanding of the dynamics of this system is fundamental since it contributes to decrease the number of incidents related to these components, to reduce the maintenance and to improve interoperability. From the mechanical point of view, the most important feature of the pantograph–catenary system consists in the quality of the contact between the contact wire of the catenary and the contact strips of the pantograph. The catenary is represented by a finite element model, whereas the pantograph is described by a detailed multibody model, analysed through two independent codes in a co-simulation environment. A computational procedure ensuring the efficient communication between the multibody and finite element codes, through shared computer memory, and suitable contact force models were developed. The models presented here are contributions for the identification of the dynamic behaviour of the pantograph and of the interaction phenomena in the pantograph–catenary system of high-speed trains due to the action of aerodynamics forces. The wind forces are applied on the catenary by distributing them on the finite element mesh. Since the multibody formulation does not include explicitly the geometric information of the bodies, the wind field forces are applied to each body of the pantograph as time-dependent nonlinear external forces. These wind forces can be characterised either by using computational fluid dynamics or experimental testing in a wind tunnel. The proposed methodologies are demonstrated by the application to real operation scenarios for high-speed trains, with the purpose of defining service limitations based on train and wind speed combination.