隧道衬砌冻胀压力问题初探

冻胀压力的量值和分布不仅取决于围岩的性态和气象条件 ,而且同衬砌结构的材料、刚度以及施工质量密切相关 ,是一个十分复杂的问题。本文从岩石和土层两种围岩中衬砌承受冻胀压力的机理出发 ,探讨计算方法。通过计算分析 ,对寒冷地区隧道衬砌的设计和施工提出了若干建议。     

大断面平顶直墙地下方厅浅埋暗挖法施工技术

本文以北京市城铁东直门车站地下方厅为工程背景,详细介绍了浅埋暗挖法多导洞施工技术在大型地下方厅建设中的应用,以及工程中对新材料、新工艺的使用,丰富了浅埋暗挖法的内容。     

Transport models, philosophy and language

The aim of this paper is to encourage debate about the nature of transport modelling. It does so firstly by considering the underlying philosophies of science (apparently) adopted by transport modellers, over a period of more than 50 years, from the 1950s until the present day. The conclusion is that a new philosophy of science needs to be developed, which is more in tune with how transport modelling is actually carried out (as opposed to how early transport modellers thought it ought to be carried out). It is recommended that such a new philosophy perceives transport modelling as a linguistic activity within the overall context of transport planning, which is in turn considered as a communication process. The paper outlines three main approaches that could be taken in this respect, analysing transport models from metaphorical, narrative and aesthetic perspectives. Conclusions are drawn upon the possible future research directions that might follow from the analysis provided in the paper, emphasising the importance of bringing formal philosophical thinking into transport modelling research and practice.

Combining technology development and behaviour change to meet CO2 cumulative emission budgets for road transport: Case studies for the USA and Europe

Global temperature rise over the long term will be proportional to the total amount of CO₂ emitted. Any given probability of exceeding a targeted maximum temperature rise implies a maximum limit on the cumulative total of CO₂ that can be emitted: a CO₂ “budget”. This paper describes an approach to modelling cumulative emissions from light and heavy duty road transport from the present to 2050, focussing on the USA and Europe, and comparing the potential impacts of a range of technological and behaviourally-based abatement measures with such cumulative emissions budgets.The model shows that abatement measures would have a lower effect on cumulative emissions from 2000 to 2050 than on annual emissions in 2050, so that focussing only on annual emissions could be misleading. It shows that technological developments would be insufficient on their own to enable Europe and the USA to meet CO₂ budgets for road transport. Behavioural changes, which potentially can be implemented much sooner, would be essential too. There is potential to keep European light duty emissions very close to CO₂ budgets, and US light duty emissions not far above the least restrictive budget, but the model predicts that heavy duty emissions in both regions are likely to exceed their CO₂ budgets. Deeper emissions reductions in other regions and sectors will be needed to compensate for this. Timing would be critical: for the greatest impact, behaviour change policies and interventions would need to be applied early and deeply.     

American Samoa: Establishing a coastal area management model for developing countries

Abstract

Debate over the appropriateness of U.S. approaches to coastal management procedures for developing countries has increased over the past few years. The coastal management program which was developed for American Samoa offers the opportunity to test the utility of the U.S. approach to CZM for developing nations.

American Samoa represents a blend of traditional and new cultures and thus may be a microcosm of developing countries. American Samoa's development of a CZM plan is examined with emphasis on similarities and differences with U.S. experience. A culture‐oriented framework is presented which can shape programs appropriate to developing countries. Finally, a process and a set of guidelines provide an outline for those attempting the difficult task of applying U.S. environmental planning and management to other countries.     

Evaluating Boating Safety Risk in Intracoastal Waterways

Growth in the number of recreational vessels that use inland and coastal waterways, coupled with the diversity of boating activities, results in increased boating-related conflicts, accidents, and fatalities. This situation has led to numerous requests from boaters, shorefront property owners, waterfront businesses, and local governments for the imposition and enforcement of boating safety speed zones within Florida's Intracoastal Waterways. A decision-support framework that incorporates Geographic Information Systems (GIS)–based risk assessment was developed to assist the Florida Fish and Wildlife Conservation Commission's Division of Law Enforcement evaluate requests and applications for the establishment of boating safety zones, pursuant to the Florida Administrative Code Rule 68-D-23.105 “Criteria for Approval of Regulatory Markers.” The risk assessment uses geospatial data compiled from multiple government agencies, survey data from subject matter experts, and public input from participatory workshops. Relevant spatial data includes waterway features and marine infrastructure from field surveys, vessel traffic patterns observed and mapped from aerial reconnaissance, and indicators of boater behaviors extracted from accident and citation reports. The outcome is a characterization of waterway segments according to perceived risk to boating safety. The application was tested in two Florida counties and it helped guide the establishment of new, and the revision of existing, boating regulatory zones within their Intracoastal Waterways. The application design is such that it is adaptable to waterways beyond those in Florida.     

重载组合列车纵向动力学的实验研究及理论分析

本文介绍了1988年6月28日至7月6日在山海关一锦州间利角育有遥 控功能的便携式测试装置进行的6400t组合列车纵向动力学试验,并 根据实测的数据对本次试验的各种工况用列车动力学软件进行了对比计 算。在此基础上对锦州机务段提出的组合列车平稳操纵方法作了评价。 本文所作工作为重载组合列车的安全和合理操纵提供了理论依据。      

建立完整的铁路重载运输技术体系 ——由大秦铁路万吨列车试验得到的启示

本文介绍了作者由夭秦铁路万吨列车试验中浙得到的一系列启示,强调, 铁路重载运输是一有庞大的系统工程,提出应建立有别于常规运输方式 的重载运输技术体系。文中并甘重载运输技术装备的发展、运用及其状 态控制,对提高重载运输组织及管理水平;甘于加强统一规划、组织与 领导,努力改善重载列车的工作环境、加强中间试验环节及做好新一代 重载列车技术发展的前期准备工作等方面提出了建议。      

"天梭"号交流传动电力机车转向架的研制

介绍了“天梭”号交流传动电力机车转向架的结构特点,并对其进行了动力学性能分析。环行线试验表明,该转向架结构设计合理、性能可靠。