公路桥涵台背施工液压夯机补强技术研究

随着人们对公路行车舒适要求的日益提高,减少台背跳车,公路桥涵台背施工受到越来越高的重视。公路桥涵台背施工液压夯机补强技术,在青海公路桥涵台背施工中已进行应用,且取得良好效果。本文以在建的大力加山至循化高速公路为例,通过对液压夯机补强桥涵台背施工技术做研究,希望在公路桥涵台背施工中得以推广。     

路桥连接处桥头表面及台背路基内部排水系统

为减少渗入台背的水和尽快排出台背内部的水,对路桥连接处桥头表面排水系统及桥台台背内部排水系统进行综述和分析.提出改善表面排水系统的措施,分析两种形式接缝的防水和排水功能,推荐出接缝的合理形式.对台背填土提出一定要求,介绍了国内外台背内部排水系统,并根据国内外研究现状和BADM实验研究结果推荐出台背内部排水系统措施.     

南百高速公路桥涵台背回填施工工艺

文章结合南百高速公路桥涵台背回填施工实践,介绍了桥涵台背回填填料的选择及施工工艺。     

注浆综合技术在公路桥涵台背施工中的应用

桥涵台背施工中,注浆综合技术是链接公路和桥涵施工的核心技术,直接影响着公路建设的质量与安全。结合公路桥涵台背施工中注浆综合技术的应用,对公路桥涵台背的施工技术及其现状进行了详细介绍,并对公路桥涵台背施工中注浆综合技术的应用做了进一步的研究与探讨。     

农村公路涵背回填施工控制方法

文章结合贺州市近年来农村公路涵洞台背回填运行状况,介绍采用碎石作为涵背回填材料及先填后挖的施工控制方法,为农村公路在涵洞建设中减少其台背下沉现象提供参考。     

浅议公路桥头及涵台背跳车的防治

在分析公路桥头及涵台背"跳车"成因基础上,提出了桥头及涵台背"跳车"的防治措施.     

道路桥梁台背沉降问题的解析

随着近年来经济的发展,全社会对于出行路面的要求也在逐渐提升,加强道路桥梁台背填筑施工技术控制、减少台背沉降量是相关人员需要关注的问题。在台背填筑施工的过程中,关键技术发挥了基础性的作用,对施工而言具有不可取代的现实意义。施工单位务必要强化台背填筑的关键技术控制,为桥梁整体质量、后期使用安全、行车舒适性提供保障。本论述针对道路桥梁台背沉降现象的客观原因进行了分析,对台背填筑施工技术的关键点进行了思考总结。     

流态粉煤灰在公路建设中的运用

简要介绍了流态粉煤灰在高速公路中的运用,采用液态粉煤灰回填桥头台背技术,解决台背施工的难题,减轻建成通车后桥头跳车问题的出现。     

泡沫轻质土台背回填工程应用研究

以泡沫轻质土在台背回填中的应用展开讨论,介绍泡沫轻质土的物理性质和力学性能,并以省道S540工程为例进行深入分析,从应用部位、方案背景、泡沫轻质土桥台台背分析等方面,详细阐述泡沫轻质土在该工程中的具体应用。实践证明,泡沫轻质土替代桥梁减跨技术可降低工程造价,台背回填还解决了桥头跳车问题,具有重要的研究意义。     

液压高速夯实机处理桥涵台背地基及效果探讨

高填方路段地基承载力的不足和自然沉降过大是造成桥涵台背填土沉降,产生桥头跳车的主要原因之一。在保证填料质量的前提下,对部分软弱地基进行处理显得尤为重要。主要介绍液压高速夯实机处理台背地基的主要性能及作业特点,并通过对比试验,对中营高速公路台背地基处理的夯实工艺及效果进行探讨。     

Substantial Changes and Their Impact on Mobility: A Typology and an Overview of the Literature

During the past 40 years, mobility patterns have enduringly changed several times as a result of the occurrence of a number “substantial changes”. Examples of such substantial changes are the rapid emergence of affordable air travel, the oil crises, and profound ICT developments. To most researchers and policy-makers in transportation, it seems more than likely that the next 40 years will also witness a number of substantial changes, some of which might even have larger impacts on mobility than the ones described above. However, literature on substantial changes and their impact on mobility are difficult to access as it is spread across different research fields and suffers from ambiguous use of terminology. As a result, overview of the literature on substantial changes and their findings is missing and discussions on the impacts on future mobility of potential substantial changes are hampered. To overcome these problems, this paper (1) proposes a typology of substantial changes and (2) ties together and reviews the scholarly literature that has focused on identifying the impacts of past substantial changes on mobility patterns. In this paper, we show how the proposed typology on substantial changes can be applied to contemplate on substantial changes and on their impacts.     

Learning aircraft operational factors to improve aircraft climb prediction: A large scale multi-airport study

Ground-based aircraft trajectory prediction is a major concern in air traffic control and management. A safe and efficient prediction is a prerequisite to the implementation of new automated tools.In current operations, trajectory prediction is computed using a physical model. It models the forces acting on the aircraft to predict the successive points of the future trajectory. Using such a model requires knowledge of the aircraft state (mass) and aircraft intent (thrust law, speed intent). Most of this information is not available to ground-based systems.This paper focuses on the climb phase. We improve the trajectory prediction accuracy by predicting some of the unknown point-mass model parameters. These unknown parameters are the mass and the speed intent. This study relies on ADS-B data coming from The OpenSky Network. It contains the climbing segments of the year 2017 detected by this sensor network. The 11 most frequent aircraft types are studied. The obtained data set contains millions of climbing segments from all over the world. The climbing segments are not filtered according to their altitude. Predictive models returning the missing parameters are learned from this data set, using a Machine Learning method. The trained models are tested on the two last months of the year and compared with a baseline method (BADA used with the mean parameters computed on the first ten months). Compared with this baseline, the Machine Learning approach reduce the RMSE on the altitude by 48% on average on a 10 min horizon prediction. The RMSE on the speed is reduced by 25% on average. The trajectory prediction is also improved for small climbing segments. Using only information available before the considered aircraft take-off, the Machine Learning method can predict the unknown parameters, reducing the RMSE on the altitude by 25% on average.The data set and the Machine Learning code are publicly available.     

地质顺层偏压隧道围岩压力及其分布特点的试验研究

结合渝怀铁路渔塘湾隧道所处的地质顺层偏压特点,按照相似理论,对地质顺层岩体作用于隧道衬砌结构上的偏压载荷进行了模型试验,初步得出了地质顺层偏压隧道围岩压力的分布特点及其与不同顺层倾角之间的变化关系,并就顺层岩体隧道结构的形式和支护措施进行了探讨。     

Physical environments influencing bicyclists’ perception of comfort on separated and on-street bicycle facilities

This study investigates the impacts of physical environments on bicyclists’ perceptions of comfort on separated and on-street bicycle facilities. Based on a field investigation conducted in Nanjing, China, we find that physical environmental factors significantly influencing bicyclists’ perception of comfort on the two types of facility. Cyclists’ comfort is mainly influenced by the road geometry and surrounding conditions on physically separated paths while they pay attention to the effective riding space and traffic situations on on-street bicycle lanes.     

Passenger conveyor economics

Operating and capital costs for a high speed conveyor are estimated from cost data for low speed conveyors and from estimates for high speed designs. Unit costs are developed with reference to theoretical and practical conveyor capacities, and to the effect of traffic peaking on average utilization. User benefits are modelled as the change in consumers surplus arising from the introduction of a conveyor on a linear street as an alternative to walking. Cost and benefits vary widely depending on system design and location and on characteristics of travellers. Benefit measurements should reflect the effects on travel demand of a proposed installation, changes in value of time with changes in mode, and the effects of benefit “dilution” associated with limitations on access to the conveyor.     

Impacts of fuel quality on indoor environment onboard a ship: From policy to practice

Environmental considerations, concerning the negative impacts of ship exhaust gases and particles on ambient air quality, are behind the requirements of cleaner marine fuels currently applied in designated emission control areas (ECAs). We investigated the impact of a ship operating on two types of fuel on the indoor air quality onboard. Gaseous and particulate air pollutants were measured in the engine room and the accommodation sections on-board an icebreaker operating first on Heavy Fuel Oil (HFO, 1%-S), and later Marine Diesel Oil (MDO, 0.1%-S). Statistically significant decrease of SO₂, NOx, PM_2.5 and particle number concentration were observed when the ship was operating on MDO. Due to the higher content of alkylated PAHs in MDO compared to HFO, the concentration of PAHs increased during operation on MDO. The particulate PAHs classified as carcinogens, were similar to or lower in the MDO campaign. Chemical analysis of PM_2.5 revealed that the particles consisted mainly of organic carbon and sulfate, although the fraction of metals was quite large in particles from the engine room. Principal Component Analysis of all measured parameters showed a clear difference between HFO and MDO fuel on the indoor environmental quality on-board the ship. This empirical study poses a first example on how environmental policy-making impacts not only the primary target at a global level, but also brings unexpected localized benefits at workplace level. The study emphasizes the need of further investigations on the impact of new marine fuels and technologies on the indoor air environments on board.     

Estimating percent-time-spent-following on two-lane rural highways

This study concentrated on estimating the percent-time-spent-following (PTSF) on two-lane highways. This measure is a key estimate of level-of-service in traffic engineering applications. Its evaluation to date has been based on simulations that yielded over-estimated values. The present study shows how to estimate this variable from easily obtained field data based on queuing theory. The estimates accord with opinions on yielding significantly lower values of PTSF that are expressed in the relevant traffic literature. An improved relationship between PTSF and two-way flow is provided by fitting the new estimates by means of the least-squares method.     

桥墩全生命周期抗震性能基于NSGA-Ⅱ的优化设计分析探究

本研究依托工程算例,借助基于NSGA-Ⅱ规则的优化设计成果功效分析的方式,对桥墩全生命周期抗震性能基于NSGA-II的优化设计功效开展专题分析探究,以为同类桥墩工程设计应用提供研究和技术参考,助力建设全生命周期抗震性能优良的桥梁桥墩工程。     

山区公路岩质边坡柔性防护与生态防护初探

西部大开发战略的实现,是以加快交通基础设施建设为前提的,而在西部多山区修建公路,难免会遇到公路岩质边坡。文章遵循边坡柔性防护与生态防护相结合的思路,以"油小线"工程为例,介绍了公路岩质边坡治理与防护的新技术,为类似工程提出借鉴。     

Individual freight effects,capacity utilization,and Amtrak service quality

This paper offers a new perspective on the post-deregulation rail industry. We hypothesize that a link exists between individual freight effects and Amtrak service quality. Specifically, we investigate the relationship between freight control of the infrastructure on which Amtrak trains operate and Amtrak train delays. Our sample consists of 1117 directional station-pairs for fiscal years 2002 through 2007 on 28 Amtrak non-Northeast Corridor passenger routes. We found that freight effects have a significant impact on Amtrak train delays after controlling for other important delay determinants such as the capacity utilization rate. The impact is higher on long-distance routes. We also observed significant differences between the effects of different freight railroads. For example, Amtrak operations on infrastructure controlled by several Class I railroads experienced significantly larger delays than baseline operations, while Amtrak train delays on Burlington Northern and Santa Fe’s tracks actually fell below baseline levels.