公路路用材料平均运距计算程序的开发应用

针对目前我国公路建设规模大、项目多、设计人员工作强度高的状况 ,通过计算机实现路用材料平均运距的自动计算 ,以减轻设计人员工作强度 ,为实现优良设计提供支持     

平均运距增长催生"省际长途重卡"继续高速增长

2008年上半年,在国Ⅲ实施、计重收费、出口市场等因素推动下,中国重卡市场得到了长足的发展.下半年重卡市场是否继续保持较好的增长趋势,其他因素暂且不谈,平均运距长期不为重视,但其对重卡市场影响相对较大,直接决定重卡市场发展的方向.平均运距是指一定时期内,平均每吨货物被运送的km数.     

高速公路软基主、次固结沉降分界点的确定

该文介绍了一种高速公路软基主、次固结沉降分界点的确定方法,该法基于饱和粘性土粘弹性流变本构律,原理可靠且简单实用;文中同时将该法应用于具体的工程实例,说明了确定主、次固结沉降分界点对于高速公路软基预压及卸载等施工的重要意义。     

土石方调配中经济运距的确定

根据借土的4种组合方式得出的土方综合单价与利用弃土方(或石方)的运输单价相比较，得出在多少运距范围内采取何种组合方式经济的结论，供同行参考。     

公路货运“平均运距”正相关牵引车市场需求

<正>公路平均运距是指一定时期内,平均每吨货物被货车运送的公里数。影响平均运距的最基本因素是货运周转总量和货运总量指标。虽然,牵引车市场需求不断增长受多种因素作用,除了受货运总量和货运周转总量基本面需求外,还要受到如公路运价指数、车辆收益性相对高、燃油税实施、其他载货车的替代需求、牵引车使用     

水运OD矩阵的推算模型研究

交通OD矩阵是交通量预测的基础,但由于资料调查工作量大且精度难以控制,水运OD矩阵往往难以通过调查直接得到.鉴于此,基于对现有OD矩阵推算模型的研究与分析,并结合水上运输及其运输量调查资料的特性,提出了一种利用水运港口吞吐量和水运客货运平均运距推算水运OD矩阵的计算模型,由此可推算得到水运OD矩阵,供相关分析研究之用.     

甲醇是我国卡车替代能源的又一选择

<正>未来20年,甚至更长时间内,传统内燃机作为汽车主要配套动力的地位将不会改变。电动车的成本、续驶里程等问题在相当长时间内难以解决,不会成为主流。对于平均运距较长的中重     

特大桥长运距箱梁高效安装研究

纵观全国各地特大型桥梁施工,有个显著的特点,箱梁安装运距超长,风险与效率呈倍增加,且是影响桥梁整体推进的主生命线。本文以一干河特大桥预制箱梁安装实例,对提高特大型桥梁长运距箱梁安装效率问题进行研究,实现最小施工成本投入,最大施工速度推进,寻求最佳性价比,具有很大的推广价值。     

拖挂运输方式有望推广应用

据了解,我国目前运输业运输资源浪费巨大,各种运输方式不能有效衔接,货运车辆空驶率高于50%,而在欧美国家,这一数字仅为20%。据统计,我国每年因车辆空驶造成的浪费高达100亿元。2005年,全国公路货运平均运距为64．79km,而欧美国家通常在300km左右。     

基于抗车辙性能的多碎石沥青混凝土骨架状态分析

抗车辙性能的正交试验表明,随着粗料含量增加,多碎石沥青混凝土骨架结构增强,抗车辙性能增强,正交分析中水平效应值为0时对应的粗料含量即为悬浮结构与骨架结构的分界点,约为66．5％。定义粗集料间隙率VCA与混合料中粗集料间隙率VCAmix为撑持度C,平均车辙深度基本上随C值的减小而减小。按体积设计法计算时,空隙率为4％时能形成骨架结构,但经现场压实空隙率达到7％后,骨架结构已被撑开,因此考虑现场压实条件下设计采用的空隙率应更低。     

加固土桩处理软基桩长与桩间距的经济组合

在软土地基上修建高等级公路,工后沉降不能满足要求时,加固土桩(水泥搅拌桩和旋喷桩)是常用的一种深层处理方法。该文通过分析计算发现,当桩长与桩间距平方的比值最小时,地基处理费用最少,这种组合称之为加固土桩处理软基桩长与桩间距的经济组合。     

重载铁路简支T梁制梁场建场技术研究

制梁场建设是重载铁路T梁建造的基础工作,建场标准化和规范化十分重要。结合课题科研成果和制梁场设计经验,对重载铁路T梁制梁场选址、关键参数确定、大型工装选型、规划与平面布置、主要土建结构物设计等组成的建场技术予以论述,以求达到技术先进、经济合理、安全适用的制梁场建设目标。     

混凝土桥梁结构随机场的相关距离分析

对随机场理论应用于混凝土桥梁结构的必要性及其理论意义进行了分析和探讨,阐明了混凝土桥梁结构随机场的相关距离的计算是可靠度分析的前提。以肇源大桥为实例进行了预应力混凝土桥梁强度的现场大量实测,以此为基础建立了该桥的强度随机场,并对该随机场的齐次性和各态历经性进行了检验。分别用相关函数法和递推平均法得到了该随机场的相关距离。结果表明,两种方法得到的相关距离比较接近,认为该相关距离可以作为工程应用的理论指导,此相关距离也可应用于其他类似的桥梁结构上。     

铁路单线特长隧道快速施工组织探究

蒙华铁路连云山隧道为重载铁路单洞单线隧道,独头掘进距离长、断面小,洞内施工交通干扰大,隧道快速施工组织难度高。为有效解决单线小断面隧道快速施工组织问题,基于隧道开挖、仰拱及二次衬砌各施工工序组织,对配套施工机械设备、工艺工法选择和施工交通组织等进行研究。通过优化和改进,较大程度上解决了单线特长隧道的快速施工难题,有效提高了单线隧道的施工效率。     

Bolster spring fault detection strategy for heavy haul wagons

An on-board health monitoring system is proposed for heavy haul wagons in this paper including a signal-based fault detection and isolation (FDI) method and an on-line fault diagnose strategy. Such a system, to be feasible on freight wagons, must be sufficiently cheap and robust, hence the design assumes the constraint of using only two accelerometers mounted on the front left and right rear part of each carbody in a heavy haul train. This paper focuses on the detection of bolster spring fault conditions. The problem is made more complex by the modes of failure which might be expected in bolster spring nests. Types of spring failure are firstly identified and discussed covering situations of broken (shortening springs) and softening (individual spring loss from a nest or cross-section loss through corrosion). The effects of these faults and their detectability were investigated using simulations on straight and curved track and using a fully detailed model of a typical 40?t axle-load heavy haul wagon. The simulation results were then examined and compared using cross-correlation analysis and an FDI system was proposed. The FDI system introduced five possible fault indicators. Initial results indicated that it was possible to detect changes in bolster stiffness of ±25%. An on-line fault diagnoses strategy is proposed for bolster spring faults which only requires data from wagon monitoring during travel around sharp curves to detect and the occurrence of confirm faults. The functionality envisaged needs only a ‘once per trip’ monitoring site, such as a sharper curve, and is aimed at condition monitoring rather than the provision of alarms or comprehensive monitoring of all events.     

Dynamic performances of an innovative coupler used in heavy haul trains

An innovative structure for a heavy haul coupler with an arc surface contact and restoring bumpstop is proposed. This coupler has a small lateral force at a small yaw angle and a limitable yaw angle to ensure an allowable coupler lateral force under intense compressive force. The main structural characteristic of the combined contact coupler is a lateral movable follower with an appropriate friction coefficient of 0.06–0.08 and a slide block with a single freedom of longitudinal movement. In order to verify and simulate the performances, a multi-body dynamics model with four heavy haul locomotives and three detailed couplers was established to simulate the process of emergency braking. In addition, the coupler yaw instability and wheel set lateral forces were tested in order to investigate the effect of relevant parameters on the coupler performances. The combined contact coupler is suitable for heavy haul train for a good dynamic performance.     

公路土石方调配优化数学模型的建立和程序设计

线性规划运输平衡问题数学模型应用于公路土石方调配，综合考虑借，弃方单价及和纵向调配运价，以最小费用为目标函数，调配方量为决策变量，调配单位（元／m^3）为价值系数，编制程序完成实现最小费用的优化调配方案，并根据需要统计输各项表格。     

A signal-based fault detection and classification method for heavy haul wagons

This paper proposes a signal-based fault detection and isolation (FDI) system for heavy haul wagons considering the special requirements of low cost and robustness. The sensor network of the proposed system consists of just two accelerometers mounted on the front left and rear right of the carbody. Seven fault indicators (FIs) are proposed based on the cross-correlation analyses of the sensor-collected acceleration signals. Bolster spring fault conditions are focused on in this paper, including two different levels (small faults and moderate faults) and two locations (faults in the left and right bolster springs of the first bogie). A fully detailed dynamic model of a typical 40t axle load heavy haul wagon is developed to evaluate the deterioration of dynamic behaviour under proposed fault conditions and demonstrate the detectability of the proposed FDI method. Even though the fault conditions considered in this paper did not deteriorate the wagon dynamic behaviour dramatically, the proposed FIs show great sensitivity to the bolster spring faults. The most effective and efficient FIs are chosen for fault detection and classification. Analysis results indicate that it is possible to detect changes in bolster stiffness of ±25% and identify the fault location.     

The stability and mechanical characteristics of heavy haul couplers with restoring bumpstop

To investigate the stability and mechanical characteristics of a type of heavy haul coupler with restoring bumpstop, the geometry and force states of couplers were analysed at different yaw angles and the longitudinal forces. The structural characteristics of this coupler were summarised. To aid in the investigation, a multi-body dynamics model with four heavy haul locomotives and three detailed couplers was established to simulate the process of emergency braking. In addition, the coupler yaw instability and lateral forces were tested in order to investigate the effect of relevant parameters on the locomotive's wheelset lateral forces. The results show that only when the bumpstop force exceeds half of the coupler longitudinal compression force, can the follower be rotated and the yaw angle of the coupler increase. The bumpstop preload is the most important stabilising factor. The coupler lateral force is constant when the coupler longitudinal force is smaller than the critical values of 2000, 1400 and 1150 kN at coupler free angles of 7°, 8° and 9°, respectively, for operation on straight track. The coupler free angle and the locomotive's lateral clearance of the secondary stopper are important in decreasing the wheelset lateral forces of the locomotive. It is advised that a smaller locomotive's secondary lateral suspension stiffness, a free clearance of 35 mm and an elastic clearance of 15 mm from the secondary lateral stopper be selected. If the coupler's free angle is less than the self-stabilising angle which is 5.5° for operation on straight track, the coupler is stable no matter how great the longitudinal force is. The wheelset lateral forces are allowed at the coupler longitudinal force of 2500 kN when the free angle is 6°. These studies establish meaningful improvements for the stability of couplers and match the heavy haul locomotive with its suspension parameters.     

公路行车视距分析与验证

针对中国行车视距测算的现状和存在的问题,基于数字仿真模型技术,提出以"视线棱体"为核心的新的空间视距测算模型,分析并建立"视线棱体"与公路模型相关面的视线通视判断标准,并以此原理研发了相应的应用软件技术,有效地提高了行车视距的计算精度;由于该计算模型和方法符合公路空间的实体关系,且其视距计算可考虑到路侧植物、护栏、标志牌等影响,因而测算结果更为准确。实际工程验证表明:"视线棱体"计算模型和方法的测算成果是可靠准确的;该方法和技术为公路尤其是双车道公路行车视距分析提供了科学而实用的技术手段,对公路安全设计与评价具有重要作用。