400 km/h高速铁路桥梁动力系数研究

为研究通行400 km/h高速列车时桥梁的动力性能,采用车-桥耦合振动方法,分析车速、车辆编组、车辆载重3种车辆因素和跨度、桥梁竖向基频、桥型3种桥梁结构因素对400 km/h高速铁路桥梁动力系数的影响.结果 表明:车速增加到一定程度将出现车桥竖向共振的风险;跨度一定时,桥梁竖向振动基频越大动力系数越小;多数工况下16...     

君威轿车最高车速60km/h故障检修

<正>故障现象有1辆君威轿车,行驶3.14万km,无法升入3挡,最高车速只有60km/h,装配的变速器是GF6六速电控自动变速器。故障诊断1.打开发动机盖,检查发动机和变速器无导线断路或插接器松动。2.用万用表检查蓄电池电压高于12V。3.检查发动机无漏油、漏水,变速器无漏油或渗油部位。4.检查仪表是否显示异常,无故障灯常亮。5.试车。油温达到正常使用温度后,用手动换挡模式使变速器逐步升     

黄韩候铁路二线复杂条件下路基支挡方案比选及设计

以黄韩候铁路二线一处复杂条件下的路基工程为例,在收集翔实可靠资料的基础上,通过各种控制因素的分析研究,开展多种支挡方案比选,提出各种控制因素的具体对策,既考虑了整体支挡方案的合理性,又充分重视各个控制点工程措施的针对性、有效性和可实施性,顺利地解决了复杂条件下路基工程难题。     

中等膨胀土作路基填料的应用条件

我国广泛分布膨胀土的地区,如何使用膨胀土作为路基填料一直是工程建设的难题。在总结膨胀土路基病害类型和产生原因基础上,以成都粘土为例,分析了膨胀力、无侧限强度和动强度随含水量、压实系数的变化,从防止膨胀土对路基稳定的不利影响的角度,讨论了膨胀土作为路基填料的应用条件。     

通车条件下路基加固的水泥-水玻璃注浆参数研究

路基注浆既要满足注浆量要求又要使浆液尽快形成强度而满足通车条件,为此,引入水泥－水玻璃双液浆理论解决上述问题。通过调节水泥－水玻璃浆液配比及注浆工艺,保证注浆量和浆液扩散半径,将每根袖阀管分4段注浆,下面3段注纯水泥浆,最上面靠近地表段注10 %的双液浆,确保靠近地表处的浆液在交通解封时尽快形成强度。检测结果表明,路基注浆加固效果良好。调整后的注浆方案既保证了注浆量、浆液扩散半径,又保证了浆体在较短时间内形成强度,满足交通及时解封条件。     

基于车内瞬变压力变化的400 km/h高速铁路隧道净空面积探讨

为推进中国高速铁路隧道技术标准深化研究,开展400 km/h隧道结构设计参数的研究工作,而隧道净空面积为其中的一项重要内容。为尝试从列车内部瞬变压力角度得到400 km/h高速铁路隧道净空面积,建立基于舒适度标准的高速铁路隧道净空面积确定方法,以控制工况为基础,通过计算和分析,从列车密封性能方面讨论维持现有隧道净空断面的可能性,并研究提出400 km/h隧道净空断面建议值。主要结论有:1)现有350 km/h单线隧道以400 km/h运营时,列车动态密封指数最低为22 s,车内瞬变压力超标的可能性较大; 2)400 km/h单、双线隧道净空面积建议值分别为85 m~2和100 m~2,对应的列车动态密封指数最低为18 s,更加符合现有标准对列车密封性能的要求,车内瞬变压力超标的可能性大幅降低; 3)提出的400 km/h高速铁路隧道净空面积建议值和对应的密封性能要求可为有关标准、规范的制订提供参考。     

Profile-speed data-based models to estimate operating speeds for urban residential streets with a 30 km/h speed limit

A speed limit of 30 kilometres per hour (km/h) has been widely introduced for urban residential streets to ensure traffic safety and allow these streets to fulfil other intended functions. However, excessive speeds on these roads are very common, causing traffic safety problems and threatening the liveability of neighbourhoods. An effective and active way to deal with speeding is the application of a performance-based design approach, as mentioned in previous research. In a performance-based design approach, street geometrics and roadside elements are selected based on their influence on the desired driving speeds. The relationship between driving speeds and street features therefore needs to be determined. Although several studies have developed operating speed models for urban streets, all of these models were calibrated based on data for streets with speed limits of more than 30 km/h. The present research is designed to investigate the influence of various roadway and roadside characteristics on operating speeds on urban tangent street sections with a 30 km/h speed limit using profile-speed data. A simultaneous equation regression with a three-stage-least-square (3SLS) estimator was used for the modelling effort. The driving speed models developed in this study incorporate several street design factors, which provide helpful information for urban planners and street designers to cope with speeding issues on residential streets.     

Drivers' perceptions regarding speeding and driving on urban residential streets with a 30 km/h speed limit

Previous studies have shown very little information regarding drivers' opinions, attitudes and behaviours with respect to speeding and driving on urban residential streets with a 30 km/h speed limit. The present research aims to address this issue by conducting a questionnaire study with a sample of 367 Japanese drivers. The results showed that drivers tended to have positive beliefs about complying with the 30 km/h speed limit and understand the negative consequences of speeding; however, a majority of the drivers considered breaking the speed limit as a way to reduce their travel time. While the extent of speeding was found to be very serious, a number of drivers still supported the use of a 30 km/h speed limit on residential streets and favoured protecting the right of vulnerable street users. The logistic regression models developed in this study identified that the drivers who did not support the 30 km/h speed limit were associated with those who had committed traffic-law violations, who had negative beliefs about complying with the speed limit, who did not consider residents' opinions, who believed it is acceptable for them to drive at a high speed, and who felt it difficult to refrain from speeding. With regard to anti-speeding countermeasures, under drivers' point of view, streets should be designed to make the 30 km/h speed limit more credible, although this study also showed evidence supporting the application of public awareness programmes and social campaigns as speeding interventions. In addition, this research investigated drivers' speed choices in various specific driving circumstances, and six underlying factors affecting drivers' speed choices were determined. On the basic of the findings, the implications and suggestions for speeding interventions were also discussed.     

新建200 km/h客货共线铁路大跨度连续刚构桥设计研究

遂渝铁路是我国第一条新建时速200 km铁路,跨越涪江和嘉陵江时采用大跨度预应力混凝土连续刚构桥。在已建成的铁路桥梁中,无论是设计行车速度、大跨桥上无缝线路设计,还是结构形式均有新的突破。介绍其结构设计,并着重对其关键技术分析进行论述。     

时速300km高速铁路基床设计的探讨

通过分层总和法计算基床的弹性变形,检验其变形是否满足规范要求。以此来确定高速铁路基床的厚度和基床表层厚度．以及合理的基床表层和底层的弹性模量。     

季节冻土区高速公路路基含水状况与冻害调查

冻胀形成的纵向裂缝和道路翻浆导致的沉陷鼓包及车辙变形是季节冻土区高速公路路基冻害的主要形式。野外调查的大量资料表明,地下水是导致路基冻害的最积极活跃的因素。它不仅侵袭软化路基,增加其冻胀,而且侵袭防冻砂砾层甚至底基层,使其失去防冻作用和辅助承载作用,致使道路翻浆破坏。这种水分来源不一定都是地下水由下向上的竖向迁移,地面水也可通过路肩边坡、失效排水沟、路面裂缝和中央分隔带等部位侵袭到路基中来,从而使路基土和结构层材料性能恶化。     

高速公路路基过湿土处理的探讨

从理论和实践方面分析了过湿土对高速公路路基施工的影响,介绍过湿土的处理措施及施工要点。     

高速铁路路基结构的动力有限元分析

从轨道的几何不平顺角度出发,提出了列车荷载的简化计算模型。通过改变基床表层、底层及地基土的刚度,利用大型通用有限元软件ANSYS对路基进行非线性动力有限元分析,揭示基床及地基刚度对路基的变形、动应力及加速度的影响,并得出了一些有意义的结论。     

时速350km高速铁路大跨度连续梁悬浇施工监控

津秦客运专线设计为时速350 km的高速铁路,该铁路线上的下邬蓟运河特大桥上跨唐津高速公路,为(80.6+128+80.6)m三向预应力混凝土连续箱梁桥,采用挂篮悬浇施工.采用桥梁博士3.0建立有限元计算模型,计算梁体线形和应力.施工中对梁体线形和应力进行实时监测,并将实测结果与计算结果进行对比.结果表明:该桥施工监控...     

铁路提速线路改造路基施工探讨

铁路第六次大提速要求轨道具有较高的平顺性、稳定性、舒适性。路基的质量是关键,根据高速铁路暂行规定,对既有线路路基病害进行彻底地整治。本文提出了路基施工要求和加固的一些方法。     

浅谈高速公路边坡生态防护

阐述目前边坡生态防护类型,分析物种选择的重要性,结合具体工程进行评述,并提出了一些参考意见。