大型开敞式油码头泊位长度的探讨

通过规范比较、公式计算与模型试验方法对合理确定码头长度进行探讨。提出在外海开敞式码头平面设计中，不要简单套用规范，而应进行细致的系缆力分析计算，找到最合理的系缆角，从而确定系缆布置和码头长度。     

基于网联车辆轨迹数据的周期排队长度估计

近年，基于网联车辆轨迹数据的交通管控与服务研究方兴未艾。其中，信号控制交叉口排队长度估计备受关注。然而，在低渗透率条件下，单个周期内轨迹稀少且提供的交通信息十分有限。现有研究仅以当前周期内网联车辆轨迹数据为输入，难以获得准确且可靠的周期级排队长度估计结果。因此，融合利用历史网联车辆轨迹数据提供的车辆到达和停车位置信息以及当前周期内实时观测的网联车辆排队信息，提出一种基于最大后验概率的周期最大排队长度估计方法。首先，依据历史轨迹数据的停车位置信息，估计排队长度的先验分布；其次，依据历史轨迹数据的车辆到达信息，估计周期内车辆的历史到达分布，并结合周期内最后1辆排队网联车辆的到达时刻与停车位置，构建排队长度似然函数；最后，基于贝叶斯理论，结合前述先验分布与似然函数，推导周期排队长度的后验分布，并采用最大后验概率方法实现周期最大排队长度的估计。仿真结果表明：所提方法在不同饱和度和渗透率条件下，均优于现有的方法；即使在车辆轨迹数不超过1 veh·周期^-1的低渗透率条件下，所提方法的平均绝对估计误差也不超过2 veh·周期^-1。实证结果表明：在渗透率仅为8.96%的条件下，所提方法的平均绝对误差为2.12 veh·周期^-1，平均相对估计误差为12.4%，同样优于现有同类方法。     

Influence of train length on in-train longitudinal forces during brake application

It needs some seconds for a signal, which is created from brake application, to travel from the first part of the train system (locomotive) to the end part of it (last wagon). Delay in time of all parts of the system (train) brake is seen which might deteriorate the longitudinal dynamic interaction of the long trains. For instance, this results in running of the rear cars to the front ones and hence producing large in-train forces at the buffers and couplers. Major parts of the rolling stock in railway system repair are known for relative compression and tension forces, which are applied to the whole train system and cause huge expenses for the industry. For trains with long lengths, operating in safe area is another important relation with train forces along the system. By using MATLAB simulation in this study, we investigated the length's effect on train dynamic along the system mainly for freight trains. We did our research on the trains which are currently used in Railways of Islamic Republic of Iran, RIRI. Four diverse cases were under our simulation, in each of which, trains consist of 52, 32, 20 and 12 cars, respectively. Two different forces (tension and compression) are displayed here as of the outcome of the research. Simulations show different forms of interplays in dynamics along the system. Then we compared the graphs to each other to find out detailed influences of length of the whole system (train including different number of wagons and locomotive) on dynamics of system along it while braking is applied.     

客运专线双线64m PRC简支梁节段预制3200t造桥机整孔架设施工技术

研究目的:为了研究大跨双线铁路64mPRC简支箱梁施工技术,研究钢桁架现浇挠度大和收缩徐变的影响,确保大跨混凝土简支梁成桥质量。研究结果:温福铁路白马河大桥双线64m简支混凝土箱梁,采用节段预制,3 200t造桥机整孔架设、现浇湿接缝和张拉控制达到了设计目的,控制了张拉时钢桁架梁对混凝土梁体反作用力的影响,成功实现了双线铁路大跨简支梁施工技术。     

大跨自锚式悬索桥吊索张拉与体系转换技术研究

为快速实现大跨自锚式悬索桥体系转换,以(160+406+160)m的双塔三跨自锚式悬索桥——桃花峪黄河大桥为背景,研究以吊索引出量控制为主、索力控制为辅的吊索张拉与体系转换技术。建立实桥有限元模型,计算吊索无应力长度,定义索头引伸出下锚垫板的长度值为引出量;采用引出量控制,从塔根向远离桥塔方向对称张拉吊索(每次8组),跨中几组吊索采取纵向相邻2组同时装千斤顶,在n号吊索张拉的同时,预拉(n+1)号吊索;进行主桥缩尺模型试验,对该方案进行验证及细节优化。研究结果及实际工程表明:采用该体系转换技术方案,主缆与吊索张力、临时墩反力、主梁应力计算值等均满足要求;缩尺模型实测应力、位移与有限元计算值吻合;主梁线形质量好,吊索索力精度高,快速实现了体系转换。     

岩堆体隧道洞口浅埋段开挖进尺的计算与分析——以云南麻昭高速公路赵家屋隧道为例

为了解决岩堆体隧道施工经验缺乏和开挖进尺选择随意性的问题,结合云南麻昭高速公路赵家屋岩堆体隧道工程实例,基于筒仓理论,提出了岩堆体隧道洞口浅埋段开挖进尺的计算公式,分析了核心土留设长度和不同岩堆体力学参数条件下的合理开挖进尺。结果表明:岩堆体隧道施工中,若不采取预支护或预加固措施,各开挖进尺下隧道掌子面安全系数均较小,掌子面存在失稳风险;留设核心土能明显提高隧道掌子面的稳定性;开挖进尺对围岩黏聚力敏感,这对岩堆体隧道稳定性不利。     

纤维微表处性能及影响因素探究

从集料级配间断与否、胶乳类型、纤维的长度这三个因素出发,对纤维微表处的性能进行研究。对于混合料的低温性能,则采用自行设计的小梁弯曲试验,以位移-力曲线下的能量积分作为衡量指标进行评价,其值越大混合料的低温抗弯拉性能越好。结果表明:在间断级配中加入纤维可以改善混合料的路用性能;胶乳B与混合料配伍性更好;纤维长度对混合料抗车辙能力影响不大,而对混合料低温抗弯拉性能影响较大,且长度的增加有利于混合料低温性能的提高。     

铁路连续曲梁管道摩阻损失及钢束伸长值的分析计算

针对兰武二线河口南黄河特大桥连续曲梁的张拉施工,分析计算了空间钢束的摩擦损失及伸长值,解决了施工控制中的关键性问题。     

Modelling and analysis of the crush zone of a typical Australian passenger train

In this paper, a three-dimensional nonlinear rigid body model has been developed for the investigation of the crashworthiness of a passenger train using the multibody dynamics approach. This model refers to a typical design of passenger cars and train constructs commonly used in Australia. The high-energy and low-energy crush zones of the cars and the train constructs are assumed and the data are explicitly provided in the paper. The crash scenario is limited to the train colliding on to a fixed barrier symmetrically. The simulations of a single car show that this initial design is only applicable for the crash speed of 35 km/h or lower. For higher speeds (e.g. 140 km/h), the crush lengths or crush forces or both the crush zone elements will have to be enlarged. It is generally better to increase the crush length than the crush force in order to retain the low levels of the longitudinal deceleration of the passenger cars.     

轨道交通线路纵断面节能坡设置研究

该文通过对城市轨道交通节能坡的节能原理和不同工况的分析研究,提出节能坡的合理设置位置,坡段长度,坡度值等建议,有效地降低轨道交通牵引能耗.