交流杂散电流干扰对管道直流电位的影响

文中利用杂散电流测试仪器,在城市管道受到杂散电流干扰区域进行了杂散电流的详细测试。选取同一条管线的4个点进行了测试,通过测试结果分析杂散电流的大小和方向,判断交流杂散电流对燃气管道直流电位的影响,确定电流流入与流出位置,确定出管线最容易遭受到腐蚀的位置。利用测试结果的分析结论确定施加排流措施方案,并测试排流后的效果。测试结果表明：排流措施施加得当,排流效果良好,能够使阴极保护系统保持正常运行状态。     

惠州管道沿线高压线交流干扰防治措施

惠州某燃气管道与高压线平行或交叉非常多,为了降低管道受到的交流干扰,给出该条管线交流干扰防治措施设计方案。首先分析了高压线对埋地管道的交流干扰方式、危害及国内外常用防治措施;然后针对惠州管道沿线高压线分布情况,给出全线交流干扰防治措施,即全线综合考虑安装固态去耦器装置,具体涉及其作用、布置和应用;同时沿线设置管道电流、电位检测装置,为后续排流效果的检测、排流规律的探索等奠定了重要基础。     

交流电气化铁路对路外管道干扰影响及防护

交流电气化铁路与埋地管道相邻时会对管道产生交流干扰。这种干扰主要通过感性耦合和阻性耦合两种方式,且大部分为间歇干扰。与铁路平行接近的管道所受干扰要明显强于与铁路交叉分布的管道。管道交流干扰程度与铁路的牵引负荷电流、管道与铁路的间距及平行长度等因素密切相关。采用钳位式排流器的接地排流措施可有效降低管道干扰电位,排流保护效果显著。     

埋地管道交流干扰的测试与防护

为了了解目标管道的交流干扰情况,使用电位自动采集仪器对管道进行了长时间的交流干扰电压监测。监测结果表明:监测管段中只有1处交流干扰强度为弱,其余位置均为强,应采取排流措施进行保护。根据前期的监测结果制定了固态去耦合器+锌带的排流方法进行交流干扰的治理。在安装完排流装置后,进行了长时间的监测,通过排流前后交流电压的对比、交流电流密度的计算和24 h的监测,结果表明治理方案可以有效减轻管道的交流干扰,降低了管道受到交流腐蚀的风险,保证了管道的安全运行。     

杂散电流排流设施有效性评价研究

随着交直流电气化铁路、高压输电线路的大量兴建,管道不可避免受到临近电气化设施的干扰。排除或者减缓杂散电流的主要途径是选择合适的杂散电流排流设施。国内目前应用的排流设施主要有极性排流器、钳位式排流器以及固态去耦合器。通过对这几种排流设施进行的现场测试与评价,总结出了每种排流方式的优点与局限性,可为今后不同干扰情况下选择合理的排流减缓方式提供依据。同时,结合现场实践,提出了杂散电流减缓的研究方向。     

埋地天然气管道杂散电流检测与评价

文中研究了涪陵页岩气田某埋地管道杂散电流干扰,进行了土壤表面电位梯度测试、管地电位测试、交流电压测试、土壤电阻率测试、SCM杂散电流重点检测.结合相关标准对检测结果进行评价发现:该埋地天然气管道全线直流和交流干扰程度均为弱,不需要采取直流或交流干扰防护措施.     

去耦合器排流技术在管道交流干扰减缓中的应用

固态去耦合器已经在国内的管道设计中得到了应用,做为交流减缓技术,固态去耦合器还可有效消除交流感应电压而不引入杂散电流或者流失阴极保护电流.文中介绍了去耦合器的一些基本特性与设计理念.测试并评价了去耦合器技术在兰郑长管道的具体应用情况.现场应用表明:去耦合器做为一种交流排流技术,可在管道的交流干扰减缓中大量推广应用.     

铁秦线管道交流杂散电流干扰检测与评价

文中介绍了交流杂散电流的危害以及国内目前检测评价指标。针对铁秦线管道受到交流电气化铁路的杂散电流干扰问题,参照目前的行业标准进行了检测和评价,采取钳位式排流措施较好地解决了现场实际问题,最后结合国内外的研究成果对管道交流杂散电流干扰的检测和评价方法进行了总结分析。     

新大线管道杂散电流干扰的分析与防护

以新大线输油管线杂散电流干扰腐蚀问题为研究对象,进行干扰调查,并现场测试管地电位、土壤电位梯度、土壤电阻率和管线的杂散电流等参数.测试结果分析充分说明干扰来源于与新大线管道近距离平行的大连快轨3号线列车的运行,其特点是双向动态干扰,没有固定的阴极区和阳极区.提出采取增加阴极保护装置和极性接地排流方式共同防护来抑制杂散电流干扰,并客观分析排流效果.分析表明排流效果良好.     

管道交流杂散电流干扰技术研究现状与发展趋势

随着经济的不断发展,高压输电线路或电气化铁路与管道的平行或交叉越来越多.管道受到的交流干扰越来越严重,文中分别从交流杂散电流干扰的特点,交流杂散电流干扰的检测、评价与减缓等方面,论述了管道交流杂散电流干扰的研究现状,比较了国内交流杂散电流干扰研究与国外的差距,提出了目前交流杂散电流减缓技术的局限性以及下一步的研究方向,可对今后交流杂散电流干扰的研究提供一定的借鉴意义.     

高铁枢纽建设与城市功能空间协同发展效率评价

随着我国高铁迅速发展,高铁建设如何与城市功能空间协同发展的问题引起广泛关注。为了评价高铁与城市协同发展的效率,本文从城市协同性、高铁枢纽建设、站城距离等角度,构建高铁枢纽建设与城市功能空间协同发展效率评价指标体系。并引入DEA模型进行分析计算其效率匹配度,为城市既有高铁站与城市协同发展程度提供依据。最后以京沪高铁为案例分析了24个车站与所在城市的协同关系效率值,结果表明,北京南站、上海虹桥站等高铁枢纽发展较好,常州北站、苏州北站、天津南站等较差,尤其是天津南站的通过能力、客流量等产出指标还需要进一步加强。     

Probabilistic risk analysis of flying ballast hazard on high-speed rail lines

Flying ballast is a significant safety concern for high-speed train operations on ballasted tracks. It is the phenomenon of a ballast particle displaced from the track, due to the aerodynamic force induced by a passing train traveling above a certain speed. Flying ballast can potentially damage tracks and rolling stock, thereby posing a risk to high-speed rail operations. This paper develops a Probabilistic Risk Analysis (PRA) model based on the information available from the field and the literature. The model enables a quantitative assessment of the probability of ballast particle displacement at a particular position on the track, as well as the probabilistic distribution of the total number of ballast particles that are expected to move. The model accounts for various risk factors, such as train speed, ballast gradation, and track position. The model application is illustrated using a ballasted track on the Yellow River Bridge on the Beijing-Shanghai high-speed rail line in China. The analysis finds that flying ballast probability increases when train speed increases, in particular, the problem of flying ballast becomes more pronounced when train speed exceeds 350 km per hour (217 miles per hour). Flying ballast probability might be reduced when the ballast profile is lower, given all else being equal. In addition, flying ballast probability is expected to be higher at the center of the track than in other positions. The proposed risk model can be further developed and ultimately be used to evaluate route-specific flying ballast risk, enabling the identification, assessment, and comparison of risk mitigation strategies in order to support emerging high-speed rail operations.     

Designing an integrated distribution system for catering services for high-speed railways: A three-echelon location routing model with tight time windows and time deadlines

An emerging task in catering services for high-speed railways (CSHR) is to design a distribution system for the delivery of high-quality perishable food products to trains in need. This paper proposes a novel model for integrating location decision making with daily rail catering operations, which are affected by various aspects of rail planning, to meet time-sensitive passenger demands. A three-echelon location routing problem with time windows and time budget constraints (3E-LRPTWTBC) is thus proposed toward formulating this integrated distribution system design problem. This model attempts to determine the capacities/locations of distribution centers and to optimize the number of meals delivered to stations. The model also attempts to generate a schedule for refrigerated cars traveling from distribution centers to rail stations for train loading whereby meals can be catered to trains within tight time windows and sold before a specified time deadline. By relaxing the time-window constraints, a relaxation model that can be solved using an off-the-shelf mixed integer programming (MIP) solver is obtained to provide a lower bound on the 3E-LRPTWTBC. A hybrid cross entropy algorithm (HCEA) is proposed to solve the 3E-LRPTWTBC. A small-scale case study is implemented, which reveals a 9.3% gap between the solution obtained using the HCEA and that obtained using the relaxation model (RM). A comparative analysis of the HCEA and an exhaustive enumeration algorithm indicates that the HCEA shows good performance in terms of computation time. Finally, a case study considering 156 trains on the Beijing-Shanghai high-speed corridor and a large-scale case study considering 1130 trains on the Chinese railway network are addressed in a comprehensive study to demonstrate the applicability of the proposed models and algorithm.     

公路桥梁伸入隧道方案探讨

包(头)茂(名)高速公路陕西境柞水至小河段出现多处桥隧相接,文章对项目中采用的桥梁伸入隧道方案进行了分析,介绍了桥梁伸入隧道方案设计施工中可能出现的问题及处理措施,如隧道断面加宽、隧道内排水系统出水口通畅、洞外管线进洞、隧道和桥台施工干扰、桥梁跨径布置等.桥梁伸入隧道方案可避免洞口高边坡,有利于环境保护,对开拓设计思路、提高选线的灵活性有一定的借鉴意义.     

The development of China's railway building

Abstract

At the birth of New China in 1949, 11 000 km of railway track were in use throughout the country. This paper describes the measures taken by the State to develop railways in the interests of the national economy. By the end of 1982 more than 52 000 km were open to traffic and much more is being built in the face of great engineering difficulties. Many lines are being electrified.

The paper also describes other measures essential for the modernization of rail transport: New China's creation of locomotive and vehicle plants, the management organization under the Ministry of Railways and the development of scientific research and educational work.

The rail density and transport capacity is still far from sufficient. Railways face a formidable task in helping China achieve the goal fixed in 1982 of quadrupling the output value of industry and agriculture by the year 2000.     

高铁运输对广西港口物流的促进作用探析

随着湘桂高铁、贵广高铁、南广高铁、云桂高铁的建成,广西逐步进入高铁时代。广西高铁的发展给广西北部湾港口群带来了新的生机,高铁与港口货物联运是未来广西北部湾港口物流发展的新趋势。文章分析了广西港口与高铁联运的有利条件以及高铁运输对港口物流的促进作用,从技术标准缺乏、货物分运混乱、物流成本偏高等方面阐述了港口与高铁联运存在的现实问题,并提出了相应对策。     

High-Speed Rail Operations on an Existing Network: An Assessment Model for China

High-speed rail operations have the potential to reduce the long-term decline in rail passenger travel demand for the medium to long distance inter-urban markets. Such decline has been evident through most of the industrialized countries where air and road transport tend to be the dominant modes. In China, the operations of long distance high-speed rail on fully dedicated track is not very easy to implement, due to the high proportion of passengers who travel between high-speed and conventional railways. An alternative approach would be to allow for mixed operations with trains of various speeds on the same track. This article puts forward a simulation model designed to allow an evaluation of the most efficient distance for high-speed rail operations under mixed train speed scenarios. The model takes into account the main operating parameters such as passenger volumes, train speeds, capital and maintenance costs, train operating costs and energy consumption. The distance of high-speed train running on conventional rail that will yield the most economic benefit can be estimated using the model. The article includes the results of using the model for a specific example. It is concluded that large-scale high-speed trains have the potential to be successfully operated on conventional rail networks.     

A model to design a national high-speed rail network for freight distribution

High-speed rail is often touted as a means to reduce congestion on the United States’ highways by removing passenger car traffic. But highway congestion can also be reduced by reducing the amount of freight traffic. So, given the advances in high-speed rail, the potential exists for developing a national high-speed network for freight distribution. To design such a network considering highway traffic and transit times, we present an uncapacitated network design model with a post-processing step for the capacity constraint. To illustrate how our modeling approach could be used by policy makers to evaluate the impacts of a high-speed rail network, we apply our models with preliminary data on high-speed rail operating parameters for freight applications and from current data on shipments from a major truckload carrier and the US Census Bureau.     

氧气管道安全运行措施的分析

首先从氧气的性质入手,对氧气管道发生燃烧、爆炸的原理进行了分析,进而针对氧气管道的特性提出了在设计阶段如何控制好氧气流速以及材料的选择、在施工阶段如何处理好焊接和保持管道的内部清洁、在管道运行阶段如何采取安全措施,通过对这几方面的严格控制,将在很大程度上降低氧气管道发生事故的概率,从而确保氧气管道的安全运行。