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既有高速铁路的线路空间线型、桥梁设施基本能够满足高速磁浮列车的开行要求,但隧道作为影响高速列车运行速度的重要因素,对于利用既有高速铁路开行磁浮列车的影响较大。空气动力学效应引起的隧道断面问题是影响隧道开行磁浮列车的主要因素,本文提出利用既有设计速度为250km/h与300~350km/h的高速铁路隧道开行高速磁浮列车的方案,包括降速、缩小列车断面积及提升车体气密性方案。以某双线铁路为例,原方案区间平均运行速度为204.8km/h。在不改变既有隧道断面的情况下,在既有高铁线路上开行磁浮列车,采用降速、缩小列车断面积及提升车体气密性方案,能够将区间平均运行速度提升至393.9~411.14km/h。由此得出,既有高速铁路隧道对开行磁浮列车具有一定的提速潜力。 相似文献
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本文为了确定高速公路隧道内提速方案具体的限速值,通过选取多条有提速需求的典型高速公路隧道进行试验,通过瞳孔面积变化率表征驾驶人在隧道内的视觉负荷程度。根据瞳孔面积变化率与机动车临界速度之间的关系,得到满足明、暗适应的视觉负荷程度对应的机动车临界速度值,取机动车临界速度分析车辆进出高速公路隧道时由于明、暗适应引起的速度变化规律;提出了以机动车临界速度值和全线提速方案对应的隧道限速值,取两者最小值作为隧道最终提速方案的限速值,然后对隧道限速原则进行修正,最后确定了原隧道路段限速60km/h、80km/h时的提速方案的具体限速值。研究结果表明:对于满足提速要求的隧道路段,原限速60km/h时,提速后的限速值取80km/h较合适;原隧道路段限速80km/h时,提速后的限速值取90km/h较合适。本文的研究具有安全性、可靠性,为日后隧道限速提供了相应参考。 相似文献
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浅埋黄土隧道洞口是隧道施工的一个关键点,关系着隧道进洞的安全.文章以设计时速为200km/h的古迹坪双线铁路隧道洞口V级围岩段的施工为例,介绍了采用大管棚超前预加固、三台阶七步法的浅埋黄土隧道的进洞施工方法.工程实践证明,此施工方法快速有效,保证了施工安全. 相似文献
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时速200 km动车组通过隧道时空气动力学效应现场试验与研究 总被引:2,自引:1,他引:1
与常规铁路隧道不同,客运专线铁路隧道设计除了要考虑满足围岩稳定性、建筑限界等外,还必须考虑高速列车在隧道中运行时所诱发的空气动力学效应的影响。文章通过遂渝线200km/h提速综合试验中的隧道气动力及结构动力学试验,对200 km/h动车组通过隧道内和列车上瞬变压力、空气动力荷载、列车风、微气压波等进行分析与研究,从而为时速200 km/h客运专线隧道的设计提供依据。 相似文献
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《现代隧道技术》2017,(5)
文章基于动力有限元理论,采用激振函数模拟列车荷载,建立了重载铁路隧道结构与围岩的耦合数值计算模型,分别分析了不同矢跨比、填充层厚度和仰拱厚度对重载铁路隧道底部结构动力响应特性的影响。结果表明:重载作用下,隧道底部结构各部位的动力响应程度较常规铁路隧道更大,对结构的稳定性更为不利。同时通过研究得出了重载作用下,隧底结构不同力学指标的最大响应值及其出现的具体位置,进一步通过设置典型参数工况,探讨了重载双线铁路隧道底部结构的合理设计参数,对于重载双线铁路隧道底部结构,矢跨比、填充层厚度、仰拱厚度分别取为1/10~1/11、1.2~1.3 m和40~50 cm较为合理,能有效改善重载双线铁路隧道底部结构的动力响应及受力状态。 相似文献
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Pedestrians as compared to vehicular traffic enjoy a high degree freedom of movement even in heavily congested areas. Consequently, there are more alternative links available to pedestrians between a given origin‐destination (O‐D) pair. This paper describes a study done by the University of Calgary to evaluate the factors affecting the choice of route on intra‐CBD trips or trips within the Central Business District (CBD). An origin destination survey conducted in downtown Calgary, Alberta enabled the identification of the most significant factors influencing the choice. These factors were analyzed in relation to the physical characteristics of the location, personal characteristics of the trip maker and the type of the trip. It appears that most people chose the shortest link and factors such as the level of congestion, safety or visual attractions were only secondary. This suggests that the length should be made a major consideration when planning and designing pedestrian links. 相似文献
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This paper estimates the efficiencies and productivity changes of 12 international airports in the Asia-Pacific region based on data from 1998 to 2006. We apply stochastic frontier analysis (SFA) to compute efficiency estimates and use the Malmquist productivity index (MPI) to analyze productivity changes. We use the SFA model with a translog-type production function after testing the statistical hypotheses. According to the results of the SFA hypothesis tests, airports have experienced a technological regression; the deviations from the efficiency frontier are caused more by technical inefficiency than random noise. However, the inefficiency was found to decrease. The MPI reveals a declining trend resulting more from technological change than from efficiency change, with a decrease in inefficiency. Taken together, both the hypothesis tests and the MPI not only provide consistent conclusions, but also suggest that airports should concentrate on technological progress. 相似文献
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In India pedestrians usually cross the road at mid-block crosswalks due to ease of access to their destination or the development of adjacent land use types such as shopping, business areas, school and residential areas. The behaviour of pedestrian will change with respect to different land use type and this change in behaviour of pedestrian further reflects change in perceived level of service (LOS). So, it is important to evaluate the quality of service of such crossing facilities with respect to different land-use type under mixed traffic conditions. In this framework, pedestrian perceived LOS were collected with respect to different land-use type such as shopping, residential and business areas. The ordered probit (OP) model was developed by using NLOGIT software package, with number of vehicles encountered, road crossing difficulty as well as safety considered as primary factors along with pedestrian individual factors (gender and age), land-use type and roadway geometry. From the model results, it has been concluded that perceived safety, crossing difficulty, land-use condition, number of vehicles encountered, median width and number of lanes have significant effect on pedestrian perceived LOS at unprotected (un-signalized) mid-block crosswalks in mixed traffic scenario. The inferences of these results highlights the importance of land use planning in designing a new set of pedestrian access facilities for unprotected mid-block crosswalks under mixed traffic conditions. Also the study results would be useful for evaluating pedestrian accessibility taking into account different land-use type and planning required degree of segregation with vehicular movement at unprotected mid-block crosswalk locations. 相似文献
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明确埋地管道防腐保温层的技术评价标准,对埋地钢质管道的安全运行,延长管道使用寿命具有重要意义。为了对埋地管道防腐保温层做出有效评价,从间接检测与开挖检测2个方面,结合现场检测数据,提出了基于防腐保温层的电流衰减率、绝缘电阻率、质量状况与厚度的分级评价标准及基于4种评价指标的综合评判方法。工程实践表明,该评价标准对防腐保温层是否存在失效能做出有效判断。 相似文献
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采用随机场模型能够有效地模拟围岩参数的空间变异性。文章将局部平均随机场理论、有限差分法和Monte-Carlo模拟结合在一起,得到了Monte-Carlo随机有限差分法,基于该方法编制了可考虑围岩空间变异性的隧道结构可靠度计算程序;并将围岩密度、弹性模量和内摩擦角等参数视为三维正态随机场,研究了围岩的竖向与水平向相关距离的变化对隧道结构可靠度的影响。计算结果表明,围岩空间变异性会显著影响隧道结构的可靠度,为了获得更为经济合理的支护方案,在支护设计时考虑围岩参数的空间变异性很有必要;围岩竖向或水平向相关距离的增大均会引起隧道结构失效概率的增加,但影响程度不同;隧道结构失效概率对围岩竖向空间变异性更加敏感,故在工程勘察费用较少时,可考虑将勘察费用更多地投入到竖向相关距离的勘测,水平向相关距离可参考已有经验数据取值。 相似文献