南宁外环公路膨胀土堑坡土质特性及防护措施

文章以南宁外环高速公路的膨胀土(岩)路堑边坡为对象,基于边坡破坏的原因及特点,开展了膨胀土(岩)边坡的土性试验,并针对边坡的不同特点,提出了坡脚矮挡土墙+浆砌片石骨架+铺两布一膜、土工格栅柔性支护、土工格室柔性支护等多种不同土工材料的边坡支护处治方案。工程实施表明所采取的方案措施能经济有效地解决南宁外环高速公路的膨胀土路堑边坡问题。     

分析风化砂改良膨胀土路基施工关键问题

文章针对风化砂改良膨胀土路基,结合实例,在系统介绍分析施工方案、基底处理措施与施工工艺的基础上,对施工控制关键点进行深入研究,并得出风化砂改良膨胀土效果显著,具有良好推广价值的结论,旨在为类似工程提供可靠的依据和借鉴。     

膨胀土路堑边坡病害处治技术

根据青临高速膨胀土路堑边坡的实际特点,分析了开挖边坡破坏的特点和原因,提出公路膨胀土路堑边坡设计支护方案和措施,有效地解决膨胀土路堑边坡病害问题。     

柔性支护技术在百色大道（一期）工程滑坡处治中的应用

文章以百色大道(一期)工程K18+720～K18+820段滑坡为工程背景,通过采用GeoStudio SEEP软件进行数值模拟分析,分析膨胀土在非正常工况下持续降雨入渗时边坡土体含水量变化和膨胀力的影响,提出了一种改进的滑坡处治柔性支护方案。结果表明,改进的柔性支护方案在膨胀土滑坡处治中效果良好,可供类似工程参考。     

膨胀土路堑边坡柔性支护处治技术研究

＂柔性支护＂处治技术是一种较刚性支护更为合理的膨胀土路堑边坡的处治方式。文章从＂柔性支护＂处治机理出发,提出了土工格栅柔性支护的处治方案,并采用有限元强度折减法对该处治方案进行了模拟计算分析。     

浅淡钦州至崇左高速公路膨胀土地基的病害处理

文章以钦州至崇左高速公路工程为例,分析了膨胀土的特性与膨胀土路基的破坏原理,提出了路基防护处治技术方案及施工要点,对类似问题有一定的借鉴意义。     

抗滑桩板式挡墙结合柔性支护在膨胀土中的应用与思考

文章以G80广昆高速公路南宁至百色路段膨胀土处治方案为例,在分析滑坡成因和计算滑坡土体物理力学参数的基础上,提出以抗滑桩板式挡墙结合柔性支护的边坡加固方案,并验算优化方案中钢板桩、抗滑桩、柔性支护的关键尺寸,同时对边坡加固施工的关键技术进行介绍,评价了加固效果。     

石油套管膨胀仿真及膨胀体锥角设计

利用ANSYS软件中的弹塑性分析模块以及接触分析模块,建立了可膨胀管膨胀过程的有限元模型.通过对多种材料在不同接触条件下所需膨胀驱动力的大小与膨胀体锥角的关系研究,确定了不同工况下膨胀体锥角的设计,并通过了试验的验证,对现场应用有指导意义.     

高速公路膨胀路基施工技术的研究

膨胀土路基是高速公路建设中的一个重要问题。本文在分析膨胀土的特性、判别方法和膨胀土路基处理不当造成的公路病害的基础上,提出了膨胀土路基的处理方法,并针对改良膨胀土处理方法和换填法的路基施工技术进行了研究,对工程实践具有一定的指导意义。     

膨胀岩土地层盾构隧道结构力学行为研究

文章在提出膨胀接触压力概念的基础上,采用接触单元对膨胀接触压力和膨胀力的关系进行了研究,得出了膨胀接触压力与膨胀岩土分布、厚度、结构及地层刚度等的关系;同时对膨胀岩土地层中盾构隧道"荷载-结构"模式外荷载及"梁-弹簧"模型的特点进行了分析;并将其分析结果直接应用到成都地铁2号线膨胀岩土地层盾构隧道的结构分析中,得出了盾构隧道在不同膨胀岩土层、膨胀力、埋深和拼装方式条件下的结构内力值,对隧道结构设计起到了指导作用。     

The Concept and Practice of Treatment for Damage in Railway Tunnel Linings Caused by High-pressure Karst Water北大核心CSCD

In recent years, railway tunnels in karst areas have frequently suffered flooding after high-intensity rainfall, which seriously affects the safety of tunnel operation and the order of transportation, and even interrupts the traffic. Based on the water hazard case in the Yuanbaoshan Tunnel on the Zhijin-Bijie Railway Line, this paper explores the causes of lining damage in terms of geology, rainfall, and the design and construction of water hazard sections, and puts forward the treatment technology for tunnel water hazards with the core concept of "making full use of existing structures and employing open drainage methods in key sections". Besides, this paper simulates and analyzes the formation of hazards and the treatment effect through numerical simulation. The results show that the subjective causes for the damage in tunnel linings include an insufficient understanding of the water-bearing formations at the geological investigation stage, the underestimation of water hazard risks posed by high-intensity rainfall during construction, and the unimproved waterproof and drainage system in the design alteration, while the objective reasons include the development of karst near the tunnel section that passes through the stratum, the strong connectivity of water conduits, and the high-intensity rainfall in a certain period of time on the tunnel site. As for the simulation results, they show that the increase of external water pressure caused by the sudden rise in groundwater level after rainstorm significantly increases the internal force of linings, and eventually leads to a much lower safety factor of sidewall linings and large scale damage, which is in consistency with the characteristics of the actual on-site damage. After on-site emergency treatment, the tunnel structure has become stable and even encountering unprecedentedly heavy rainfall twice, the tunnel has still remained in a good condition. Since then, no water hazards and other disasters have occurred, which proves that the treatment plan is valid. © 2022, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Port Economics,Policy and Management: Content Classification and Survey

This paper presents a taxonomy and analysis of the content of published research in port economics, policy and management (port studies). The recent increase of these publications suggests a growing interest in the study of ports. However, the research characteristics and directions of this research field are unidentified. This paper provides a systematic analysis of port studies published during the period 1997–2008. A comprehensive cross-citation and analysis of the themes, approaches and findings of all 395 relevant journal papers identifies the extent to which the research field is maturing, and the leading papers. This paper also presents an extensive analysis of the content, based on the classification of all port studies into seven research themes. For each theme, research topics, widely used research questions, concepts and research methods and the most important research findings are discussed. Finally, we identify emerging research challenges and research questions that still need to be answered.     

Assessing systematic sources of variation in public transport elasticities: Some comparative warnings

There is an extensive and continually growing body of empirical evidence on the sensitivity of potential and actual users of public transport to fare and service levels. The sources of the evidence are disparate in terms of methods, data collection strategy, data paradigms, trip purpose, location, time period, and attribute definition. In this paper, we draw on a data set we have been compiling since 2003 that contains over 1100 elasticity items associated with prices and services of public transport, and car modes. The focus herein is on direct elasticities associated with public transport choice and demand, and the systematic sources of influence on the variations in the mean estimates for fares, in-vehicle time, and headway obtained from 319 studies. The major influences on variations in mean estimates of public transport elasticities are the time of day (peak, all day vs. off-peak), the data paradigm (especially combined SP/RP vs. revealed preference (RP)), whether an average fare or class of tickets is included, the unit of analysis (trips vs. vkm), specific trip purposes, country, and specific-mode (i.e., bus and train) in contrast to the generic class of public transport.     

隧道粉尘颗粒物的危害及控制措施分析

目前我国隧道大规模快速的发展,而钻爆法以其高效、经济的特点在隧道建设过程中起着至关重要的作用。然而,施工期隧道钻孔、爆破、喷射混凝土、出渣等施工工艺都会扬起大量粉尘颗粒物,严重危害现场人员的身体健康,降低施工现场的能见度影响施工效率和安全,同时大量颗粒物加剧机械设备磨损,在一定程度上影响了设备的使用寿命。结合隧道开挖过程,根据粉尘在隧道内分布规律,粉尘产生因素及运移机理,通过比较隧道减尘、降尘、排尘、除尘、阻尘五种控制措施的特点,提出与现场相适应的粉尘颗粒物综合防治措施,从而减小粉尘的危害,提高现场施工环境质量。     

基于LEAP模型的城市客运交通能耗和污染物排放预测

我国交通运输业能源消耗量与污染物排放量日益增多,交通部门的节能减排措施研究迫在眉睫。本论文基于LEAP模型构建了某城市客运交通能耗与污染物排放模型,并预测了基准情景、政策情景、技术情景及综合情景下该城市客运交通2014-2030年之间的能耗及污染物排放情况。研究表明,三种发展情景下该城市能源需求量及污染物排放较基准情景均有减少,其中综合情景效果最佳,综合情景在2030年的能源消耗与CO2排放可分别减少56.98%和54.55%,CO、HC、NOx与PM2.5可分别减排67.39%、67.27%、51.43%与75.38%。因此应大力发展公共交通,尤其是轨道交通,同时限制私家车的无节制发展,并推广节能环保技术以改善终端利用层次能源结构。     

Modelling the resilience,friability and costs of an air transport network affected by a large-scale disruptive event

This paper deals with developing a methodology for estimating the resilience, friability, and costs of an air transport network affected by a large-scale disruptive event. The network consists of airports and airspace/air routes between them where airlines operate their flights. Resilience is considered as the ability of the network to neutralize the impacts of disruptive event(s). Friability implies reducing the network’s existing resilience due to removing particular nodes/airports and/or links/air routes, and consequently cancelling the affected airline flights. The costs imply additional expenses imposed on airports, airlines, and air passengers as the potentially most affected actors/stakeholders due to mitigating actions such as delaying, cancelling and rerouting particular affected flights. These actions aim at maintaining both the network’s resilience and safety at the acceptable level under given conditions.Large scale disruptive events, which can compromise the resilience and friability of a given air transport network, include bad weather, failures of particular (crucial) network components, the industrial actions of the air transport staff, natural disasters, terrorist threats/attacks and traffic incidents/accidents.The methodology is applied to the selected real-life case under given conditions. In addition, this methodology could be used for pre-selecting the location of airline hub airport(s), assessing the resilience of planned airline schedules and the prospective consequences, and designing mitigating measures before, during, and in the aftermath of a disruptive event. As such, it could, with slight modifications, be applied to transport networks operated by other transport modes.     

Reprint of “Modelling the resilience,friability and costs of an air transport network affected by a large-scale disruptive event”

This paper deals with developing a methodology for estimating the resilience, friability, and costs of an air transport network affected by a large-scale disruptive event. The network consists of airports and airspace/air routes between them where airlines operate their flights. Resilience is considered as the ability of the network to neutralize the impacts of disruptive event(s). Friability implies reducing the network’s existing resilience due to removing particular nodes/airports and/or links/air routes, and consequently cancelling the affected airline flights. The costs imply additional expenses imposed on airports, airlines, and air passengers as the potentially most affected actors/stakeholders due to mitigating actions such as delaying, cancelling and rerouting particular affected flights. These actions aim at maintaining both the network’s resilience and safety at the acceptable level under given conditions.Large scale disruptive events, which can compromise the resilience and friability of a given air transport network, include bad weather, failures of particular (crucial) network components, the industrial actions of the air transport staff, natural disasters, terrorist threats/attacks and traffic incidents/accidents.The methodology is applied to the selected real-life case under given conditions. In addition, this methodology could be used for pre-selecting the location of airline hub airport(s), assessing the resilience of planned airline schedules and the prospective consequences, and designing mitigating measures before, during, and in the aftermath of a disruptive event. As such, it could, with slight modifications, be applied to transport networks operated by other transport modes.     

Rural mobility and mode choice: Evidence from the 2001 National Household Travel Survey

This article uses data from the 2001 National Household Travel Survey (NHTS) to compare travel behavior in rural and urban areas of the U.S. As expected, the car is the overwhelmingly dominant mode of travel. Over 97% of rural households own at least one car vs. 92% of urban households; 91% of trips are made by car in rural areas vs. 86% in urban areas. Regardless of age, income, and race, almost everyone in rural areas relies on the private car for most travel needs. Mobility levels in rural areas are generally higher than in urban areas. That results from the more dispersed residences and activity sites in rural areas, which increase trip distances and force reliance on the car. Somewhat surprisingly, the rural elderly and poor are considerably more mobile than their urban counterparts, and their mobility deficit compared to the rural population average is strikingly less than for the urban elderly and poor compared to the urban average. Data limitations prevented a measurement of accessibility, however, and it seems likely that rural areas, by their very nature, are less accessible than urban areas, especially for the small percentage of car-less poor and elderly households.     

绿色公路理念在漳武高速公路设计中的思考与实践

随着我国高速公路网基本形成,目前新增高速公路建设项目多位于山区腹地及偏远地区,这些地方往往基本农田资源稀缺、陆域、水域生态、自然保护地分布多、范围广,生态环境保护要求高,因此对于绿色公路理念的贯彻和落实显得尤为重要。本文从集约通道资源、保护土地资源、生态选线、多元化服务区设计等方面详细阐述了绿色公路理念在漳武高速项目勘察设计中的应用情况,实践表明绿色公路设计对于控制资源占用、减少能源消耗、降低污染排放、保护生态环境、拓展公路功能、提升服务水平方面起到了极大的提升作用。     

International private and public reinforcing dependencies for the innovation of automotive emission control systems in Japan and USA

In the beginning of the 1970s, the economies of USA and Japan were growing fast and environmental pollution was increasing to alarming levels. As passenger car emissions were found to be significant and rapidly increasing, their reduction was specially targeted. Following a bill passed by US Congress in 1968, requirements were set in 1970 for the vehicle manufacturers to reduce the emissions of carbon monoxide (CO) and hydrocarbons (HC) with 90% by 1975, and nitrogen oxides (NO_x) with 90% by 1976. These requirements were soon adapted to the Japanese regulatory framework, and were known in both countries as the “Muskie Act” or “Muskie Law” after the senator who developed the original bill.The new requirements spurred tremendous research and development efforts. Car manufacturers and research institutions in USA, Japan and Europe investigated and developed alternative solutions, including gas turbine and steam engine vehicles. California, the USA state with the most severe air quality problems and the only state at the time allowed to establish more strict requirements than federal regulation, established requirements implying the use of oxidation catalysts in 1975 and three-way catalysts (TWC’s) in 1977. Japan as a nation adopted similar requirements 1976 and 1978. Export of cars from Japan to USA increased rapidly. The rest of USA adopted emission standards similar to California’s only in 1981, timing USA vehicle sales rebound after the energy crisis and grave economic downturn. Strict requirements were thus established only after more than a decade of civic and legal processes between federal authorities, the car manufacturers and NGO’s.The history of vehicle development is one of cooperation and competition. This paper argues that the international cooperation on different levels of society (government, industry and science) together with commercial competition between the two countries was strong, continuous and instrumental in enabling the development of technology, appropriate regulation and infrastructural changes and thus created a market for cleaner cars and effectively reduced emissions from the growing vehicle fleet. In other words, the introduction of TWCs was reinforced by the simultaneous development of mitigating technology in two car producing countries competing for market space.