广西路网公路沥青路面病害调查及分析

文章通过广西路网公路沥青路面大规模现场病害调查和室内试验,分析了路网公路沥青路面的主要病害类型及损坏特征,建立了路面残余空隙率、面层强度、油石比、基层强度等性能指标与路面损坏之间的关系,可为沥青路面设计及施工提供参考。     

沥青路面的离析控制

沥青路面离析是高等级公路路面早期损坏的一个重要原因,结合日常监督检测的经验,从沥青路面离析的成因、检测及防治等方面,论述了沥青路面的离析控制.     

沥青路面预防性养护过程中再生沥青的应用

文章简单介绍了公路沥青路面预防性养护的概念及其常用的养护技术,阐述了使用沥青再生进行公路沥青路面预防性养护的适用条件,分析了沥青再生技术的作用机理及效果。以工程实例来说明沥青再生技术的使用效果,旨在为解决公路沥青路面的早期病害,提高公路的安全性。     

半刚性基层沥青路面结构优化设计

文章在对沥青路面早期损坏原因进行分析的基础上，探讨了解决路面早期损坏的途径，提出了采用组合式基层的优化设计思路，并对组合式基层沥青路面结构进行了设计分析，认为组合式基层沥青路面是一种比较适合于重载交通的路面结构。     

公路沥青路面早期破坏及防治

针对目前我国公路沥青路面常常出现早期破坏,并严重影响高速公路外观和服务性能的现状,分析了公路沥青路面常见早期破坏类型及其产生原因,提出了相应的防治措施。指出沥青路面早期破坏不仅与设计、施工等环节有关,而且与公路使用、养护和管理联系紧密,为此需要把握好每个施工环节,严格按照施工规范和操作规程施工,做好公路的养护、管理工作,这样才能减少沥青路面病害,提高沥青路面的质量,延长路面使用寿命,提高投资效益。     

不同沥青路面结构抵抗车辙性能理论计算分析

车辙是沥青路面早期损坏主要形式,特别在陡坡及超载的条件下,沥青路面车辙病害更为突出。文章拟定了5种沥青路面结构组成,建立有限元模型计算了各种沥青路面结构的力学参数,对各种路面结构抵抗车辙的性能进行了分析对比。     

高效能红外线就地加热再生技术在石安改扩建工程中的应用

阐述高等级沥青混凝土路面早期损坏的原因及病害,利用高效能红外线就地加热技术,解决了沥青路面出现的裂纹、裂缝、坑槽、网裂的修补问题,提高了沥青路面的养护质量。     

浅析沥青路面早期微裂缝修复机理

微裂缝是沥青路面早期损坏的主要形式之一。文章从流体动力学角度分析沥青路面早期微裂缝成因及其危害,介绍沥青路面养护剂用作封闭微裂缝、防止渗水的机理。     

沥青复原剂在西北地区恢复老化沥青面层性能的应用

介绍了沥青路面恢复剂的应用原理及在新疆沥青路面中应用的初步体会:通过室内试验及工程实践得出:在沥青路面基层强度满足使用性能要求的前提下,沥青路面恢复剂能恢复老化沥青的性能,较好的处理路面微裂、松散、老化等病害;提高路面的整体强度,防止或推延断裂缝、龟裂、剥落、坑洞、坑槽等严重病害的出现,延长沥青路面的使用寿命。由此提出公路养护新观念———对公路路面进行早期维护,可有效的降低道路养护成本,提高公路养护工作的经济效益和社会效益。     

沥青路面早期施工质量评估体系研究

高速公路沥青路面的早期施工质量控制对于公路整体质量以及竣工后的使用寿命均具有重要意义。文章通过对高速公路沥青路面早期施工常见质量问题进行分析,详细归纳了产生问题的原因,建立了高速公路沥青路面早期施工质量评估体系,并通过试验验证了该施工质量评估体系的正确性,为高速公路沥青路面早期施工质量控制提供借鉴。     

支架法在海中箱梁现浇施工中的应用

针对海中箱梁现浇施工中的工程量大、工期紧迫、悬臂法施工不能满足工期要求和施工难度大等问题,文章结合青岛海湾大桥箱梁现浇施工实践,介绍以钢管桩支撑作为承载基础,采用贝雷梁与碗扣式支架相结合的支架,成功地解决现浇箱梁施工难题的方法。     

开挖工况对偏压连拱隧道结构及上覆山体稳定性的影响

文章采用弹塑性有限元数值模拟,对不同开挖工况下地形偏压连拱隧道围岩及主体结构的应力场、位移场、破坏区分布进行了分析,研究了开挖工况对隧道上覆山体稳定性的影响。分析表明,当先开挖浅埋侧隧道时,围岩、结构及上覆山体稳定性都要优于先开挖深埋侧隧道的方式,其计算结果可为同类隧道的设计、施工提供有益的参考。     

Catching the tail: Empirical identification of the distribution of the value of travel time

Recent methodological advances in discrete choice analysis in combination with certain stated choice experiments have allowed researchers to check empirically the identification of the distribution of latent variables such as the value of travel time (VTT). Lack of identification is likely to be common and the consequences are severe. E.g., the Danish value of time study found the 15% right tail of the VTT distribution to be unidentified, making it impossible to estimate the mean VTT without resorting to strong assumptions with equally strong impact on the resulting estimate. This paper analyses data generated from a similar choice experiment undertaken in Sweden during 2007-2008 in which the range of trade-off values between time and money was significantly increased relative to the Danish experiment. The results show that this change allowed empirical identification of effectively the entire VTT distribution. In addition to informing the design of future choice experiments, the results are also of interest as a validity test of the stated choice methodology. Failure in identifying the right tail of the VTT would have made it difficult to maintain that respondents’ behaviour is consistent with utility maximisation in the sense intended by the experimenter.     

基于声电类比法的管系气柱固有频率的计算

基于平面波动理论与电学系统方程的等价,建立管道气柱单元声学等效电路.采用MATLAB/SIMULINKL软件,通过谐振法对气柱系统进行电路仿真,得到其各阶固有频率,并与传递矩阵法计算结果相比较,误差很小,说明采用声电类比法计算气柱固有频率是有效的.     

武汉长江隧道盾构段结构型式研究

武汉长江隧道是我国在高水压、强透水地层中修建的第一条大直径盾构隧道,且左侧河床历年冲淤变化幅度较大,如何选择合理的隧道结构型式是工程设计必须考虑的关键问题.为此,在国内外现有单层管片衬砌和全环双层衬砌的基础上,研究提出了一种新型的“管片衬砌+非封闭内衬”的双层衬砌结构该结构在不增加隧道开挖直径的前提下,允分利用圆形隧道底部和两侧的富余空间现浇钢筋混凝土,并与车道板结构共同组成非封闭二次衬砌结构,可以大幅度地减少河床冲淤变化时的结构横向变形,并确保隧道底部与两侧这些重点部位的防水性能及结构长期稳定性,是一种值得推荐的创新结构方案.     

川气东送天然气管道线路水合物形成预测

为了更好地预测、分析和处理水合物造成的不良后果,以川气东送管道为例讨论了天然气水合物的形成原因,提出了输气管线水合物预测模型,并建立了水合物形成预测的压力和温度计算模型,编制了“水合物预测软件”,预测该管道线路和场站的水合物形成条件和易形成水合物的区域.文中通过以上方法很好地预测了川气东送管道水合物的形成区域及情况,该预测方法可用于天然气管道线路水合物的形成预测.     

On the income elasticity of the value of travel time

Transport infrastructure is long-term and in appraisal it is necessary to value travel time savings for future years. This requires knowing how the value of time (VTT) will develop over time as incomes grow. This paper investigates if the cross-sectional income elasticity of the VTT is equal to inter-temporal income elasticity. The study is based on two identical stated choice experiments conducted with a 13 year interval. Results indicate that the relationship between income and the VTT in the cross-section has remained unchanged over time. As a consequence, the inter-temporal income elasticity of the VTT can be predicted based on cross-sectional income elasticity. However, the income elasticity of the VTT is not a constant but increases with income. For this reason, the average income elasticity of the VTT in the cross-sections has increased between the two survey years and can be expected to increase further over time.     

紧邻有轨电车高架桥基坑施工安全保障措施

结合苏州太湖大道改造工程阳山西路隧道基坑工程,文章分析了紧邻有轨电车高架桥基坑施工时存在的风险及相应安全保证措施,研究了各主要施工工序的控制要点,并对施工期间可能出现的风险提出了针对性的应急措施,不仅可以确保基坑的安全和稳定,而且将基坑施工对高架桥的影响降到最低,安全保障措施可供类似工程参考。     

原油管道检测器通过能力评价方法

为了探明管道内部通过能力,保证管道内部腐蚀检测器的顺利投放,制定了由泡沫检测器到几何尺寸检测器的管道通过能力检测流程,并将此方法在多条原油管线上进行了验证。结果表明：该方法能准确地识别管线上的变形尺寸大小,并对变形部位进行定位。根据检测结果对管道通过能力进行评价,对不符合要求的管段及时进行修复,保证了后期检测的顺利进行。此外,在检测的过程中有效地清理了管道内部污物,提高检测器通过能力及管道的输油效率。     

An analysis of the methods used to calculate the emissions of rolling stock in the UK

The aim of this paper is to analyse and compare the methods used for calculating emissions of UK rolling stock based on their type and mode of operation. The three modes under comparison were; diesel, electric and bi-mode. As well as comparing these three modes of operation, a comparison between Conventional, Freight and High Speed Rail was made. Alternate fuels were considered for diesel and bi-mode locomotives and compared based on their environmental impact. The emissions of trains were studied using three methods. Specifically, the three chosen methods were used to calculate the emissions of each train and a comparison of these methods was made. In the current UK energy climate, diesel trains emit less emissions than electric trains when factoring in mechanical and air resistances. Bi-mode trains have their place in the UK network but with electrification of the network currently in place, this mode of operation will become redundant in the near future. High Speed Rail, although time efficient, releases high emissions due to energy consumption increasing with the square of speed. Alternative fuels, such as biodiesel, should be a consideration for the future of rail, as emissions fall dramatically with content of biodiesel in fuel blends.