某湖底隧道中等强度等级清水混凝土研究

针对某湖底隧道敞开段C30清水混凝土的配合比设计,采用图像处理技术定量评价清水混凝土的外观质量,研究分析了砂率、胶凝材料用量、矿物掺合料等配合比参数对混凝土外观质量的影响,并根据试验结果确定了该隧道清水混凝土的基础配合比.研究结果表明,适当增加砂率、提高胶凝材料用量以及双掺矿物掺合料可以改善混凝土外观质量.     

提高侵蚀环境下山岭隧道衬砌混凝土耐久性施工对策研究

通过调查发现,我国既有山岭隧道结构耐久性普遍不足,许多隧道运营后不久衬砌结构就出现了开裂、渗漏水、溶蚀结晶、甚至出现拱顶掉块,造成隧道结构耐久性不足,其原因有设计原因也有施工方面的原因.文章针对既有隧道的病害表现,分析了隧道衬砌耐久性不足在施工方面的原因,并提出了解决新建隧道衬砌混凝土耐久性的主要施工对策:采用多元复合胶凝材料及合适的混凝土搅拌工艺;采用低水胶比、低用水量和高性能减水剂;采用先进的灌筑和振捣工艺、合理的养护技术及拆模和养护时间等.     

路用再生骨料透水混凝土的力学性能优化研究

路用再生骨料透水混凝土(PRAC)的力学性能直接影响再生骨料透水混凝土道路的质量。文章基于PRAC的破坏机理,从两个方面研究其力学性能的优化:(1)在普通硅酸盐水泥的基础上,往PRAC的胶凝材料中分别掺入硅灰、粉煤灰、磨细矿渣粉等矿物掺合料和增强料、外加剂等进行试验,研究胶凝材料的力学性能并分析其作用机理,从而提高水泥石强度;(2)对增加骨料之间的接触点数量和面积时PRAC力学性能的变化规律进行改性研究。结果表明:通过掺入不同矿物掺合料可以显著提高再生骨料透水混凝土水泥石的强度;通过改变PRAC的骨胶比,增加骨料颗粒表面包裹的胶凝材料的厚度,可优化PRAC的力学性能,提高PRAC的强度。     

隧道衬砌混凝土抗硫酸盐侵蚀耐久寿命预测模型研究

文章通过对硫酸盐侵蚀机理的分析,得出了自然劣化衰减方程;并根据规范中规定的混凝土强度耐蚀系数低于75%时混凝土寿命到期的基本原则,建立了混凝土抗硫酸盐侵蚀的耐久寿命预测模型;同时选取主要参考点建立了硫酸根质量浓度、水胶比、矿物掺合料掺入种类和掺量,以及不同养生方式的影响系数函数。综合考虑这些因素对衬砌混凝土耐久性的影响,得出了混凝土抗硫酸盐侵蚀的寿命预测方程,并对各种胶凝材配方混凝土的耐久寿命进行了预测。预测结果表明,多元复掺胶凝材对混凝土的抗硫酸盐侵蚀具有良好的效果,考虑多因素的混凝土寿命预测模型简单实用。     

隧道管片修复试验研究及施工技术

针对运营隧道破损管片在隧道特殊环境的修复难题,开发出一种适应隧道内施工时间短、顶部施工难度大等特点的结构修复胶。通过对材料凝结时间、压缩强度、与混凝土粘结强度、耐久性等一系列的试验研究,提出盾构法隧道破损管片修复工法,并进行了工程应用。试验结果显示,隧道修复材料初凝时间短,抗下坠性能好,早期强度高,与管片粘结性能满足隧道特殊施工要求,特别适合运营期隧道顶部管片修复施工的特殊要求,应用前景良好。     

新型绿色无熟料碱渣胶凝材料

文章以碱渣、脱硫石膏和矿渣为主要原料,掺入少量粉煤灰和激发剂,通过正交试验配制出碱渣胶凝材料。试验表明配制的胶凝材料达到复合32.5水泥技术要求。同时发现脱硫石膏的掺量为15%左右时,胶凝材料的强度最好;矿渣的掺量越大,胶凝材料的强度越高。     

高流态抗渗混凝土在隧道衬砌工程中的应用

文章介绍了高流态抗渗混凝土的流化机理,从不同角度论述了混凝土拌合物的组成对流变参数及硬化混凝土性能的影响.通过高流态抗渗混凝土在隧道衬砌工程中的应用实例,证明高流态抗渗混凝土完全可以应用于隧道衬砌工程,并能取得较好的质量效果和经济效益.     

镁水泥在公路工程中配合比设计

镁水泥做为气硬性胶凝材料,它具有节能环保、强度高、胶凝性能强、耐久性强、和易性好,空气稳定性和耐侯性、抗盐卤腐蚀性能好,能够快速凝固,具有良好的抗渗性、以及具有快速养护容易等优点。它作为新型的公路工程用材料,现根据我们在镁水泥试验段中的经验及总结,进行镁水泥配合比设计探讨。     

高性能混凝土在盾构隧道管片中的应用

文章结合高强混凝土在南京地铁隧道衬砌管片中的应用,探讨了影响高性能混凝土在混凝土管片中应用的因素.高性能混凝土应用于隧道衬砌管片对降低管片造价、增强管片耐久性和抗渗性有重要作用.     

聚脲喷膜材料在隧道衬砌掉块病害整治中的试验研究

针对传统掉块病害整治工艺施工工序复杂、劳动强度大、施工速度慢、工效低和费用高等缺点，提出采用聚脲喷膜材料对隧道衬砌掉块病害进行整治。通过对聚脲喷膜材料承受掉块自重和空气动力学荷载的理论分析，以及现场建立隧道衬砌模型的实测试验，重点研究了聚脲喷膜材料的粘结强度和拉伸强度。试验表明，在试块自重和空气动力学效应约14 t荷载的共同作用下，厚度为5 mm的聚脲喷膜材料未发生拉伸断裂破坏，能够承托住衬砌掉块；加载过程中试块周边一定范围内的喷膜材料发生了剥离，表明剥离范围内喷膜聚脲材料与隧道衬砌混凝土表面之间粘结强度逐步降低。为防止隧道衬砌拱部掉块，可采取增加喷膜材料与混凝土之间的粘结强度或增加喷膜材料厚度等措施。     

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.     

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。     

管道施工组织设计

在管道工程建设中，管道施工组织设计是一项重要的经济管理性文件，也是验证施工企业在工程建设中具有的施工实力和管理水平的综合技术能力体现。它对工程建设项目施工全过程活动的质量、进度、技术、安全、经济和管理组织起着不可估量的重要作用。     

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.     

波纹管应力分析研究进展

评述了波纹管应力理论研究方法的进展情况，围绕解析法、工程近似法和数值法，对波纹管理论研究中的一些主要成果作了较详细的回顾和总结，对各种研究方法作出了评价，展望了亟待解决的一些问题。     

Evaluation of pedestrian crosswalk level of service (LOS) in perspective of type of land-use

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.     

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。