港珠澳跨海集群工程海底沉管隧道防火设计

港珠澳跨海集群工程海底隧道是目前世界上最长的公路沉管隧道,运营期设置有主动与被动的双重防火系统。结合港珠澳海底沉管隧道的主要技术特点,提出防火设计中热释放率、火灾次数、耐火等级以及采取防护措施后构件的主要耐火指标。依据工程防火的具体实施条件,通过综合比较,沉管结构防火设计采用防火板直接覆面方式,沉管接头防火采用由刚性防火板与柔性防火隔断共同组成的具有自主知识产权的双层防护系统。     

Violent water-structure interaction: Overtopping features and vertical loads on a fixed structure due to broken incident flows

This paper presents an alternative experimental study of the interaction of broken flows with a fixed structure, concerning the overtopping features and vertical loads over its deck. Wet dam-break tests were carried out to generate incoming flows. Synchronized measurements provided by high-speed cameras, water elevation and force sensors, were used to investigate the influence of tank length in overtopping behaviour and the patterns and loads formed by wet dam-break flows generated by different conditions. During some of the overtopping events analysed, large scale plunging waves were observed, hitting the deck directly and forming large air cavities. These events generated violent interactions with the structure, causing significant loads and chaotic behaviour over the deck, due to the combination of air cavity collapse, reactive splash and run-down. The present approach could be employed as an alternative to study interactions of broken incident flows with different types of fixed structures, allowing the acquisition of detailed data to compare analytical or numerical models.     

地下水对边坡稳定性影响之评估与对策——以南回铁路沿线边坡为例

台湾位于欧亚板块与菲律宾海板块交界带,岩体破碎且地下水丰沛,暴雨期间易肇生坡地灾害。台湾南回铁路沿线多处隧道边坡具有浅岩覆与常渗水的现象,若坡地发生失稳将严重影响铁路营运安全。采用区域地下水经营观念,以水文地质模式分析、评估降雨和地下水对边坡稳定性的短期与长期影响,并透过情境模拟方式评估各种排水配置对隧道边坡稳定性的提升程度,并研拟优化的工程方案以降低致灾风险。     

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提出一种适用于在城市中构建高速关键线路的信号配时方案.与以往只注重根据车流量适时调整信号灯的方案相比,该方案强调将关键道路上某一方向上的所有车辆分段,把每一个有效车流段看作一个整体,让其按规定速度行驶,当这些有效车流段到达叉路口时,让信号灯为其调整绿灯,而当其全部通过叉路口,在路上行驶时,让信号灯转为红灯,利用下一段车流到来前的时间间隙供另一方向的车辆通过,由于这些车辆在行驶过程中避开了所有红灯,中途无需停车,因此平均速度提高一倍以上.本文将详细阐述车流分段、行车规则和信号配时等的具体构想,并用实验验证该方案的可行性和高效性.     

长江口细砂在崇启通道工程中的应用

利用大型移动式足尺加速加载设备MLS66,通过现场百万次加载的全程监控和动态分析,从湿度状态、模量衰减、塑性变形累积等方面,揭示了自然环境和反复荷载耦合作用下公路结构的工作状态和工程响应特征,全面论证了利用长江口细砂填筑高等级公路低填路基的可行性,为公路长期性能保障措施的设计与实施奠定了科学的基础,并且根据长江口细砂的工程特性实现了公路建设的资源节约化。     

Managing evacuation networks

This paper proposes a non-anticipative, adaptive, decentralized strategy for managing evacuation networks. The strategy is non-anticipative because it does not rely on demand forecasts, adaptive because it uses real-time traffic information, and decentralized because all the information is available locally. It can be used with a failed communication network.The strategy pertains to networks in which no links backtrack in the direction of increased risk. For these types of networks, no other strategy exists that can evacuate more people in any given time, or finish the evacuation in less time. The strategy is also shown to be socially fair, in the sense that the time needed to evacuate all the people exceeding any risk level is, both, the least possible, and the same as if less-at-risk individuals did not participate in the evacuation. The strategy can be proven optimal even when backflows happen due to driver gaming.     

基于计算机测控的汽车ABS台架试验系统的研制

针对目前教学和科研用ABS试验台存在的不足,根据机电混合模拟理论[1,2],分析建立了汽车运动惯量和道路制动力台架电模拟数学模型,以Labview软件为平台,运用动态链接库技术,设计了新型ABS试验台。该试验台可对被测车辆的运动惯量、附着系数进行在线调整,模拟精确,操作方便。     

基于线性路段行程时间描述的交通输出流特性

已知路段输入流u(t)条件下,利用动态交通分配模型中广泛使用的路段行程时间与路段车流量具有线性关系即τ(t)=α βx(t)的模型,给出了路段输出流v(t)的一般表达式和路段行程时间的递归表达式。在路段车流满足先进先出(FIFO)的条件下,结合任意时刻t的车流量表达式和线性路段行程时间模型得出了输出流v(t)与输入流u(t)的关系式。并由此得出了时刻的路段车流量表达式,从而给出了关于路段行程时间更明确的结果。根据文章的结论,对文献[2]中的实例进行了数值仿真,验证了其结果;同时运用道路交通流调查所得到的数据,进行了数值仿真,所得结果与实际相符。     

基于二流理论的宏观交通评价模型的建立

为研究宏观道路网络交通特性,以二流理论为基础,建立道路网络宏观交通特性的评价模型。该模型引入图论的分析方法,考虑可达性的评价指标和街道的实际交通情况,全面而抽象地描述城市道路网络路段与交叉口之间的关系,并给出道路网络宏观交通特性的评价指标,最后以一简单实例说明利用该模型评价城市道路网络宏观交通特性的过程。     

Decomposing travel times measured by probe-based traffic monitoring systems to individual road segments

In probe-based traffic monitoring systems, traffic conditions can be inferred based on the position data of a set of periodically polled probe vehicles. In such systems, the two consecutive polled positions do not necessarily correspond to the end points of individual links. Obtaining estimates of travel time at the individual link level requires the total traversal time (which is equal to the polling interval duration) be decomposed. This paper presents an algorithm for solving the problem of decomposing the traversal time to times taken to traverse individual road segments on the route. The proposed algorithm assumes minimal information about the network, namely network topography (i.e. links and nodes) and the free flow speed of each link. Unlike existing deterministic methods, the proposed solution algorithm defines a likelihood function that is maximized to solve for the most likely travel time for each road segment on the traversed route. The proposed scheme is evaluated using simulated data and compared to a benchmark deterministic method. The evaluation results suggest that the proposed method outperforms the bench mark method and on average improves the accuracy of the estimated link travel times by up to 90%.