南水北调穿黄隧洞有粘结环锚预应力施工重难点分析

南水北调穿黄隧洞工程为我国首次采用盾构管片拼装式结构与衬砌预应力结构相结合的新型双层复合衬砌型式,隧洞内衬直径7 m,衬砌厚度45 cm,仅为直径的1/16,较常规混凝土偏薄,而且要承受单束锚索2 250 kN的张拉力,预应力偏高。为了解决薄壁混凝土环锚预应力施工中出现的锚具槽裂纹、钢绞线伸长值不足及预埋波纹管堵塞的难题,依托南水北调穿黄隧洞工程,采取理论分析计算、现场张拉试验等方法,探讨并解决了隧洞薄壁混凝土有粘结环锚预应力施工的技术难题,相关研究成果可供类似工程借鉴。     

Quality of pedestrian flow and crosswalk width at signalized intersections

Among various pedestrian facilities, signalized crosswalks are the most complex and critical ones. Their geometry and configuration including width, position and angle directly affect the safety, cycle length and resulting delays for all users. Existing manuals do not provide clear and rational specifications for the required crosswalk width under different pedestrian demand combinations and properties. Furthermore, they do not consider the bi-directional flow effects on crossing speed and time when addressing pedestrian flow at signalized crosswalks. However, quantifying the effects of such interactions on the behavior of pedestrian flow is a prerequisite for improving the geometric design and configuration of signalized crosswalks. The objective of this paper is to develop a methodology for estimating the required crosswalk width at different pedestrian demand combinations and a pre-defined LOS. The developed methodology is based on theoretical modeling for total pedestrian platoon crossing time, which consists of discharge and crossing times. The developed models are utilized to generate the fundamental diagrams of pedestrian flow at signalized crosswalks. A comprehensive discussion about the effects of bi-directional flow and various pedestrian age groups on the characteristics of pedestrian flow and the capacity of signalized crosswalks is presented. It is found that the maximum reduction in the capacity of signalized crosswalks occurs at roughly equal pedestrian flows from both sides of the crosswalk. By utilizing existing LOS thresholds for pedestrian flow at signalized crosswalks, the required crosswalk widths for various pedestrian demand combinations are proposed for implementation.     

交叉相遇局面中船舶避碰行动的不确定性

通过对船员避碰行动调查,根据信息熵理论研究评价了在交叉相遇局面中让路船舶两船间初始ＤＣＰＡ和距离采取避碰行动种类的不确定性,并与在接近对遇局面的相应情况进行了比较,为处于相应局面船舶的避碰决策提供参考。     

The effectiveness of differential pricing on route choice

The use of differential pricing as a means of traffic management has been advocated by specialists in the field of transport for quite some time. Because of technical and political reasons, a full-scale pricing scheme for the use of road space has yet to be introduced. Applying the principle to a highly automatic rail system, however, is technologically much more feasible. The Mass Transit Railway Corporation of Hong Kong has implemented a so-called revenue neutral peal pricing policy after the completion of a second cross-harbour route- the East Harbour Crossing — in May, 1990. Passengers travelling from Kowloon to the central business district (including Jordon and Tsim Sha Tsui on the Kowloon side and stations from Sheung Wan to Causeway Bay on the Island side) during the morning peak hour are confronted with the following choice: either (i) make use of the Nathan Road Corridor and pay 80 cents on top of normal face; or (ii) take the less congested but in general longer route via the East Harbour Crossing and get a 80 cents discount. The present paper attempts to analyse the effectiveness of this differential pricing policy in diverting passengers from the overcrowded section to the less heavily utilized route. A personal interview survey comprising a total of 1094 successful cases was conducted for this purpose. The logit regression model was employed to analyse the route choice. It is found that income, habit and journey time are the most important variables determining the route choice. The effect of cost or fare difference, although large in terms of magnitude, is only marginally significant in the statistical sense. It is suggested that efforts to change the passengers' habit and measures to shorten the train transfer time at the Quarry Bay Station for the East harbour Crossing users would be more effective in achieving this end. This is especially the case given the current political development in Hong King which renders further enlargement of the price difference a highly difficult proposition.     

武九客运专线西南下行联络线特大桥主桥桥式方案比选

武九客运专线西南下行联络线特大桥主桥跨越3条既有铁路线路,桥梁与既有铁路线路夹角仅16°。为了选出主桥最合理的桥式方案,从安全、适用、经济、施工对既有铁路的影响等各方面进行计算及分析对比,比选结果表明,主跨148 m矮塔斜拉桥为本桥的最优桥式方案。     

解决ZPW-2000A型无绝缘轨道电路对DX3型道口信号干扰问题

文章对叠加在ZPW-2000A型无绝缘轨道电路上的DX5型道口信号设备错误报警问题，提出了合理的解决方案。     

杭州湾跨海大桥VTS软科学研究

船舶交通管理系统(VTS)是一项牵涉面非常广、极复杂的系统工程，开展软科学研究，是合理规划和科学管理的前提和依据。杭州湾跨海大桥桥区水域建立船舶交通管理系统，条件、情况比较特殊复杂，应该更加重视和加强实现系统功能所必须依赖的软科学研究。     

拖网渔船避碰行为的不确定性分析

通过对交叉相遇局面中单拖网渔船避碰行为的实际调查，应用信息熵理论，建立了避碰行为的不确定性模型。借助对交叉相遇局面中的让路船在不同距离、不同DCPA时采取避碰行动的不确定性分析，为相应局面中的船舶避碰决策提供参考。     

弯道诱发道路交通安全事故分析

道路交通安全关乎我们的切身利益,其诱发因素颇多,而弯道是交通安全事故高发地。文章从汽车行驶特性、不良视距、会车超车等方面入手,分析弯道诱因与交通安全事故间的内在关系,并提出了基于GPS、GIS信息系统工程的智能交通预警思路,为交通安全控制提供理论参考依据。     

浅覆土高水压强透水地层注浆法更换盾尾刷技术

为了改变冷冻法止水更换盾构盾尾刷施工成本高、工期长的行业现状,解决浅覆土、高水压、强透水地层更换盾构尾刷止水难度大、渗漏风险高的技术难题,南京纬三路过江通道N线工程采用提前预制特殊管片,增加径向预留注浆孔,不断优化注浆配比、注浆参数和注浆工艺,进行有效注浆的方法,并配以相应的辅助措施,最终达到更换盾尾刷时的止水要求,顺利完成了复杂地质条件下的超大直径泥水盾构盾尾刷更换施工,比采用冷冻法加固止水大大节约了工期和成本,具有较高的社会效益和经济效益。