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盐湖地区修建高速公路,因构造物处在对混凝土有很强腐蚀性的重盐渍土(氯盐硫酸盐)路段,所以对构造物施工质量有很高的要求,也对施工质量管理形成了很大的挑战.就大察高速公路察尔汗盐湖(万丈盐桥)路段的桥梁防腐施工质量控制进行阐述. 相似文献
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格茫公路地处重盐溃土地区,由于盐渍土具有特殊的物理化学性质,使该地区的公路经常发生翻浆等病害,严重影响交通运输和公路养护的正常运行.通过工程实践对盐渍土地区路基、路面、土工布施工及路基特殊处理等工艺进行分析,从施工方面有效控制盐渍土地区公路的施工质量,防止和减少翻浆等病害的发生,提高盐渍土地区道路使用功能. 相似文献
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先张法施工采用的槽式台座和墩式台座成本高,难破除,复耕费用高。介绍了新型先张法台座的设计方案、制作工艺以及张拉工艺的改进。 相似文献
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在红砂岩地区的公路施工中最常遇到的问题是大量的红砂岩土因其材料本身的特殊性难以作为路基填筑材料而被丢弃。文中通过分析红砂岩的特性,就施工中采用何种设备及工艺对红砂岩进行处理,以确保填筑路基的稳定性进行了探讨,有效地解决红砂岩土利用难的问题。 相似文献
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高温蒸汽管道直埋的设计与施工 总被引:2,自引:1,他引:1
针对南方地下水位较高的地区土壤潮湿、盐碱性大的情况,提出了采用钢套管、复合保温结构的直埋方式,即以钢套管作为外保护层,蒸汽管道在套管内可以自由伸缩,钢套管在受热后不会老化、裂开以至漏水,内部蒸汽管道及保温材料的工作条件是稳定可靠的;提出了直埋蒸汽管道疏水的地面布置的新工艺,避免了传统的疏水井设置,极大地减少了工程量,对直埋施工提出了具体的注意事项,并借助工程实例,对保温材料的选用、保温层厚度及管道热补偿进行了具体的计算,阐明了在高地下水位地区高温蒸汽管道直埋的可行性。 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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《Transportation Research Part A: General》1991,25(6):407-418
The main deficiency of most current modeling approaches to transportation can be identified as neglect of the integration of existing geographical knowledge in regard to the ex ante transport/land use modeling approaches, with its focus on territorial dynamics and theory development. This paper addresses this aspect of the problem by introducing a theoretical and methodological framework for the analysis of the interrelationship between land uses. The analysis attempts to determine to what extent the functional land use in a city can be considered an ordered pattern. The order sought does not rely on purely spatial configurations, but on the correlation of transportation and land use. The first section of this paper focuses on theoretical considerations. It stresses the fact that conventional approaches do not apply in the present context. It then suggests an alternative based on areas of influence and measured in terms of level of attractance of land uses. The second describes a procedure based on this alternative following the remarkable contribution of Hanjoul, Beguin and Thill. An application of this procedure to the analysis of Shanghai is then examined. Finally, an evaluation of the strategies for optimizing the interrelationship between land uses is presented. The paper concludes with a possible research agenda. 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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介绍了城市轨道交通工程中杂散电流不同的监测系统的构成,分析了集中式、分散式和智能型等监测系统的配置和功能,以及智能型实时在线监测系统的重要意义,为轨道交通工程杂散电流监测系统的选择与应用提供参考。 相似文献
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天然气自动计量系统有多种组态软件,由于软件的不相通性,造成了计量系统数据采集的通用性差、数据传输与入库的时效性差、数据利用的可靠性低.结合各组态软件的实际情况,从设计上充分利用Oracle大数据处理能力以及Partition(分区表)的特性,实现历史数据的存储,应用WebService与COM+数据访问组件提供多层数据访问架构,采用OPC与DDE工业数据交换协议,实现了各站场计量数据的实时上传,为连续数据采集和实时监控提供了可能,节约了改造成本. 相似文献
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Joseph N. Prashker 《Transportation》1979,8(4):329-346
Reliability of travel modes was found to be the most important characteristic of transportation systems in several attitudinal investigations of individual travel behavior. This paper represents the first part of a research effort aimed at gaining a better understanding of the characteristics of reliability of transportation modes in urban travel. In this research, reliability characteristics are identified; their importance relative to each other is assessed, and an insight into possible structure of an objective reliability index is discussed. The research is based on perceived values of reliability, which were identified through a large attitudinal survey conducted in the Chicago metropolitan area. 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