沉管隧道管段预制阶段温度场仿真分析

钢筋混凝土沉管隧道管段制作过程中水泥的水化热是主要的升温因素，先浇注的底板对侧墙变形形成约束，致使管段侧墙容易产生裂缝，通常在外侧墙内布置冷却管以控制温度裂缝。以上海外环线越江隧道为工程背景，采用有限元法对管段的温度场进行数值模拟，分析了在冷却作用下管段温度场的分布与变化规律，为管段温度裂缝控制的设计与施工提供依据。     

施工期仿真分析在船闸廊道工程中的运用

船闸廊道是混凝土裂缝易发部位,文章依托施桥三线船闸工程,采用大型有限元分析软件ANSYS对施工期廊道进行仿真分析,通过对施工期温度场、应力场的仿真计算和结构优化研究,探讨了廊道温度场、应力场分布规律及随时间的变化规律,为施工期廊道混凝土裂缝的控制提供理论依据。     

南京长江水底隧道施工期通航问题研究

依据南京长江水底隧道隧址河段的航运基本情况以及沉管段施工工序组成.分析了沉管施工期对航运可能产生的影响.提出了相应的航道维护方案和安全维护措施.并采用航迹线计算方法对航道维护方案进行验证.得出了沉管施工期隧址河段通过采取措施仍可维持通航的结论.     

含特殊管段的热油管道稳态温度场计算方法

特殊管段会影响热油管道运行的安全,为此详细探讨了含特殊管段的热油管道稳态温度场计算方法,建立了管道稳态运行的热力模型,利用有限元法对其进行求解.在计算管道轴向温度时,提出不同管段取不同环境温度;在求解横向温度场时,对埋地段提出不同埋深利用不同热影响半径,而对架空段和浸水段,则利用虚拟热影响区.模拟实例表明:特殊管段对管道的热力特性影响会给管道停输再启动的预测带来不利,充分证明了文中方法在计算含特殊管段的热油管道稳态温度场时的实用性.     

浅谈沉管隧道起浮与抗浮设计

沉管隧道结构设计与普通隧道的结构设计不同,沉管隧道管段不仅要满足结构受力要求,也要满足起浮及浮运期间的干舷高度,以及运营期间的抗浮安全系数要求.文章根据影响管段干舷及抗浮的主要因素,浅谈沉管管段起浮与抗浮设计,为以后沉管隧道管段设计提供参考.     

疏水装置放水管温度场的数值模拟

水蒸汽管道中的冷凝水由疏水装置排出。为研究极寒地区疏水装置放水管冬季结冰的问题,采用计算流体力学软件Fluent建立了放水管死管段热损失的物理模型,并对管道内部温度场进行模拟分析。模拟结果很好地显示了管道内的温度场,并得到了管道轴线上的温度分布,结果表明:死管段长度对管道内温度场有重要影响。将死管段长度控制在0.2 m以内,可有效避免放水管冷凝水结冰的问题。     

隧道施工期地质超前预报技术的发展

近年来,随着隧道施工技术的提高,对隧道施工期地质超前预报提出了更高的要求.受地质勘察精度、经费等诸多条件的限制,设计与实际不符的情况屡有发生,由此造成的隧道洞内塌方、涌水、涌泥、涌砂、岩爆、瓦斯爆炸等灾害时有发生,给隧道施工造成极大的危害.隧道施工期地质超前预报显示出越来越重要的作用.本文在回顾隧道施工期地质超前预报技术的发展及其应用的基础上,对隧道施工期地质超前预报技术的发展前景进行了预测.     

沉管隧道管段接头防水研究--数值模拟分析

从沉管隧道施工的特点可知,管段与管段之间的接头防水十分重要,若接头之间水密性不能得到保证,会危害整条隧道的安全使用.文章通过沉管隧道管段接头首道防线,也是最重要防线的GINA止水带的数值模拟研究,对GINA止水带不同压缩量下的防水能力、压缩剪切情况下的防水能力及耐久性等情况进行了模拟、计算、分析.望对今后类似的大型沉管隧道管段接头的设计、施工有所帮助.     

上海外环沉管隧道管段基础压砂法施工技术

管段基础处理是沉管法隧道施工中的重要环节,文章以上海外环沉管隧道管段基础处理为工程背景,对压砂法的机理及其试验进行说明,对压砂施工的流程及工艺、安全与质量的控制方法进行了介绍,并对管段的沉降进行了分析.     

沉管隧道测量技术

文章针对大型曲线沉管隧道的特点,论述了曲线沉管隧道的平面及高程控制测量、管段特征点标定测量、管段沉放测量,以及管内测量的方法,并给出了相应的计算公式.     

Analysis of factors affecting the choice of route of pedestrians

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.     

输油管道中原油乳状液的流变性研究

原油乳状液的流变性是原油开采后在管道中输送的重要研究方面,为了更好地研究这一性质,采用电动搅拌机、偏光显微镜以及流变仪等仪器来测定不同含水率的原油乳状液在不同条件下的黏度,观测不同含水率的原油乳状液在偏光显微镜下的形态。并且分别对原油乳状液的黏度与含水率之间的关系以及与剪切速率之间的关系进行研究,初步确定了所测区块原油乳状液的转相点以及该区块原油乳状液的流变特性,为生产中的油气集输提供了理论依据。     

Preliminary results of an analysis of areas of influence in Shanghai

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.     

城市轨道交通杂散电流监测系统概述

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。     

埋地管道防腐保温层失效评价

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。     

实现多组态计量软件集中监控的可行性分析

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.     

注汽管道承压能力评估和实物试验验证

基于失效评估图技术对某注汽管道进行了承压能力评价,给出了管线在不同腐蚀壁厚情况下的极限承压能力和极限裂纹尺寸。并利用实物爆破试验验证了评价方法的安全性和有效性,通过对爆破断口进行宏观和微观分析,发现管段的开裂属于脆性开裂。     

Direct analysis of the perceived importance of attributes of reliability of travel modes in urban travel

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.     

盾构隧道管片接头抗剪力学性能研究

通过对南京长江盾构隧道环向管片接头进行的三组原型抗剪(无螺栓剪切、有螺栓逆剪和有螺栓顺剪)加载试验,分析研究了管片接头在剪力作用下的受力、变形和破坏特征,给出了管片接头混凝土接触面的静摩擦系数,得到了接头剪力主要由混凝土接触面承担、破坏形式为连接斜螺栓剪切延性破坏的结论。通过对管片结构的有限元数值模拟计算得出:接头处的剪力与轴力比小于接缝面的摩擦系数,管片不会发生相互错动,结构是稳定的。     

Non-parametric analyses of efficiency of airports

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.