无纵向风下环境压强对拱顶最高温度影响数值研究

为了给高海拔隧道火灾防灾救援设计提供参考依据，通过火灾动态模拟软件(FDS)建立全尺寸模型隧道，设置5种不同环境压强，研究环境压强对隧道火灾拱顶最高温度的影响。结果表明： 1)相同火源热释放速率(HRR)下，拱顶最高温度随着压强降低而增大； 2)环境压强降低引起的空气密度与卷吸强度变化是造成拱顶最高温度变化的主要原因。基于理论分析和数值计算结果，提出考虑环境压强的拱顶最高温度预测模型。预测模型拱顶最高温度与考虑环境压强的无量纲热释放速率的2/3次幂成正比，试验数据验证了预测模型的可靠性。     

Establishment of a Dredged Material Disposal Site in the Exclusive Economic Zone: New Zealand

Disposal options for muddy dredged material, especially if lightly contaminated, is an issue facing many countries, particularly if environmental protection and adherence to the Protocols of the London Dumping Convention is a regulatory requirement. For the case of the oceanic islands of New Zealand, disposal of muddy dredged material has become an issue for the prime city of Auckland. Accordingly, it has been necessary to investigate a suitable marine disposal site outside of the territorial seas in the exclusive economic zone (EEZ). Ideal properties for such a disposal site include a near flat surface on the continental shelf, with sediments of similar textural characteristics to the material being disposed, a site of non-critical benthic ecology, water depths sufficient to enable the disposal site to be monitored (as required under the London Dumping Convention), a site experiencing low shelf currents, not affected by significant wave agitation, and a site not of cultural significance. The approach for site establishment and gaining consent for disposal activities is reviewed. Preliminary investigations supporting a proposed site on the continental shelf in the EEZ are presented.     

高黎贡山隧道1#高地温斜井降温处理技术研究及比选

为解决高地温隧道工程中存在的作业环境差、机械设备故障多、劳动生产率低等高温热害问题,以大瑞铁路高黎贡山隧道1#长大斜井为背景，进行技术研究和降温方案比选。首先,分析热水源、监测隧道洞内外气象条件，通过加强通风措施改善人体的舒适度。其次，采用注浆封堵热水源，减少热水流量，控制施工环境的湿度和温度；采用冰块+射流风机+快热交换的处理措施，冰块吸收隧道内热量，降低局部环境温度；采用机械制冷设备进行强制降温，改善热害隧道施工环境；综合优化资源配置，采用增加作业人员和设备数量，倒班作业，缩短人员和设备作业时长等多种处理措施。最后，分析各种降温措施能够达到的施工效果。结果证明，针对以围岩、热水为主要热源的高地温隧道施工，采用“通风降温+注浆堵水+机械降温+合理施工组织”的处理方案，符合高地温隧道施工的技术要求。     

筑养路机械在低温条件下的使用 与 保养

鉴于我国筑养路机械在低温条件下的使用与保护存在诸多问题， 通过对筑养路机械在低温条件下的使用与保养分析，提出筑养过程中要根据低温条件与机械技术情况变化，合理、有效地进行筑养路机械的使用与养护，从而确保机械的正常使用，同时避免事故发生，保证施工质量。     

The Economics of Using Ocean Observing Systems to Improve Beach Closure Policy

Beach closure policies in the United States suffers from two shortcomings. Type I errors, in which clean beaches are closed, results when managers resort to extensive beach closures because they are unsure of the spatial extent of water contamination. Type II errors, in which contaminated beaches remain open, occur because the time from sampling to public notification can be between two and nine days. Coastal Ocean Observing Systems (COOS) could reduce the impact of both Type I and II errors. The COOS could reduce the spatial extent of beach closures by better predicting the fate of contaminants in coastal waters. An improved COOS also could reduce the time from sampling to public notification of contamination events. I estimate the lost recreational value associated with Type I errors (unnecessary closures) and the public health costs associated with Type II errors (unnecessary exposure to waterborne illnesses) for beaches in Southern California.     

Road pricing: some further comments

This paper extends the discussion of certain problems associated with road pricing raised in an earlier contribution to this journal. Firstly it is shown that where the value of time varies between different groups of traffic using the same congested road, optimal road pricing requires price discrimination between the groups such that those with the lowest value of time pay the highest charge and suffer the greatest losses. However, a uniform price based on an “equity” value of time would reduce the relative distributional effects. Secondly the paper takes up the suggestion that queueing (and by extension congestion) may be positively helpful in the allocation of resources and shows that this is not in general correct although there are situations in which the use of queueing alongside conventional pricing may have a role to play. Finally it is argued that governments’ apparent lack of enthusiasm for road pricing stems as much from political considerations as the more technical problems of applying it.     

盾构进出洞处地基水平杯型冻结加固的温度场研究

上海城市轨道交通某线在冻结法加固盾构进出洞工程在穿越一中间风井时采用水平杯型冻结技术。通过冻结温度场分析,验证了该风井处进出洞冻结工程设计中杯身冻结器比杯底冻结器长1.1 m的合理性,同时验证了水平杯型冻结壁设计在盾构机进出洞冻结工程设计中的科学性,为同类工程设计和施工提供借鉴。     

温度梯度作用对开裂后预应力混凝土箱梁桥性能影响

温度梯度作用是引发预应力混凝土箱梁桥开裂非常重要的一个原因。全国许多学者都积极参与此领域的研究,得出许多有价值的结论,但普遍的分析模型中并未考虑裂缝引起部分部位刚度降低的影响,而很多裂缝在施工过程就已经出现。研究温度梯度作用下箱梁桥不带裂缝工作状态与带裂缝工作状态的内力变化,分析裂缝对结构刚度的影响及其引起的内力变化。     

Exposure of Fauna to Off-Road Vehicle (ORV) Traffic on Sandy Beaches

Driving of off-road vehicles (ORVs) on sandy beaches is common and widespread, but is not universally embraced due to putative environmental impacts on beach biota. For ORVs to impact the beach fauna, traffic areas must overlap with faunal habitat: a fundamental pre-requisite for impact assessments but as yet un-quantified for sandy beaches. Thus, this study quantified the spatial and temporal patterns of ORV traffic on five Australian beaches, and measured the degree to which the distribution of intertidal macro-invertebrates overlaps with traffic zones. Traffic volumes on beaches can be considerable (up to 500 vehicles per day). The position of beach traffic across the beach-face is principally governed by tides and driver behavior. Despite driver education campaigns to the contrary, a considerable fraction of vehicles (16–67%) traverses the soft, upper shore near the foredunes. The majority (65%) of burrowing invertebrate species of the intertidal zone is directly exposed to traffic, save for species inhabiting the swash zone. Because beach traffic presents a formidable management challenge, a fundamental first step in identifying whether ecological impacts are indeed likely, is to assess the potential for spatial and temporal conflict between human pressures (e.g., ORVs) and biological resources (e.g., beach fauna). Although this potential is certainly substantial for sandy shores used by ORVs, the actual ecological impacts on the intertidal fauna can only be predicted in situations where the responses (e.g., direct mortality, behavioral changes) of individual species to beach traffic are known.     

关于城市道路建设工程交通影响评价的若干思考

目前在国内还鲜有类似"城市道路建设工程交通影响评价"的提法和应用。通过将其与《建设项目交通影响评价技术标准》中所涉及的相关内容进行比较分析并总结实践经验,探讨了该项工作开展的必要性,以及所应包含的内容。