盾构泡沫系统优化改造及现场试验研究

在地铁隧道施工中,泡沫系统是影响土压平衡盾构掘进安全、质量和效率的重要因素。文章以杭州地铁一号线盾构隧道工程为依托,针对盾构自带泡沫系统自身不易控制、维修不便、系统复杂且不独立等缺陷,提出了优化改造措施,意在使泡沫系统完全国产化和独立化;通过改造前后泡沫系统操作性、精度控制、系统故障率及经济效益四方面的比较,证明了优化改造后泡沫系统的优异性能;同时,基于优化改造后的泡沫系统,针对杭州粉砂性土的地层条件下进行的盾构推进时泡沫系统施工参数的现场试验,分析了不同泡沫量对刀盘扭矩、推进速度的影响,结果表明泡沫参数适用于粉砂性土层中的盾构掘进。     

超大直径土压平衡盾构施工土体改良试验研究

盾构推进时开挖面的稳定对控制沉降起着决定性作用,因此要求作为开挖面支撑介质的土砂具有良好的塑性变形、软稠度、内摩擦角小及渗透率小等特点,但是一般土壤不能完全满足这些特性,为此需要对开挖面土体进行改良。目前土体改良技术主要是在土体内加入膨润土、泡沫等添加剂来改善土体的性能,但是该技术对于超大直径、工程环境敏感的上海外滩通道工程是否适应值得探讨。为此,以上海外滩通道工程为背景,通过室内试验、模拟试验和现场试验研究了土体改良技术对超大直径土压平衡盾构隧道的适应性问题;通过室内试验验证了泡沫和膨润土对上海典型土体的改良效果;根据模拟推进试验结果确定了添加剂加量、发泡率等参数;最后通过现场试验探讨了改良效果。通过在超大直径土压平衡盾构施工中对土体进行改良,有效地保持了开挖面的稳定,减少了盾构推力与扭矩,刀盘磨损和机械负荷也都得到了很好的改善,盾构在土体改良后出土流畅、推进匀速,从而验证了土体改良技术对超大直径盾构隧道的适用性。     

大型泥水平衡式盾构施工技术初探

本文以延安东路复线隧道２００ｍ构试推进试验为工程背景，着重介绍了大型泥水平衡式盾构在软弱地中层中掘进隧道的施工技术，并就该类盾构的开挖面稳定机理展开讨论。文章根据试推进试验结果，提出了泥水平衡式盾的最佳参数匹配方法，同时浅论了盾构推进系统、泥水处理系统和同步注浆系统的管理技术。     

盾构隧道防水技术应用及工艺改进

地下工程防水技术应在工程实践中不断予以改进,由此提高防水质量,使之得到持续地完善。结合湛江湾跨海盾构隧道接缝防水材料工艺设计优化,从设计和施工的角度对盾构隧道结构自防水、接缝防水及防水材料的技术现状和工艺优化进行阐述。以期通过不断优化改进,使防水技术在盾构隧道施工应用中得到进一步的发展。     

上海崇明越江通道长江隧道工程综述（一）——长江隧道工程设计

介绍了上海长江隧桥（崇明越江通道）工程的建设背景、规模和上海长江隧道建设的自然条件;阐述了工程总体设计方案,以及超大直径盾构隧道管片结构、大深度高水压管片防水、长距离隧道通风系统和防灾体系等关键技术方案;描述了两台Ф15430泥水加压复合盾构机的性能特点;叙述了隧道总体施工方案和盾构隧道施工正面稳定、大直径隧道抗浮、长距离施工测量、内部结构同步施工、成淡交替土层环境条件下连接通道施工等长大越江隧道关键施工技术方案和风险预案措施。     

盾构隧道施工风险知识管理系统的设计开发

介绍适用于盾构隧道施工期风险的管理流程,并构建出一套盾构隧道施工风险评价体系和盾构隧道施工风险知识管理系统的新概念。该系统可促进施工企业知识资源的优化配置,同时通过对工程施工期风险进行有效管理,有利于施工企业对施工成本、工程进度、工程质量和环境安全的全面控制。     

超大直径隧道管片纵向螺栓施工期间断裂原因分析

超大直径盾构隧道施工期间螺栓断裂是复杂的力学过程。它受到盾构施工过程中诸多因素的影响。通过对螺栓受力状况的试验,并结合盾构推进过程中相关参数、盾尾同步注浆量及注浆压力、隧道沉降监测数据,详细分析了管片纵向螺栓断裂的原因,可供类似工程参考和借鉴。     

大直径泥水平衡盾构在冻结加固土体中的进出洞施工技术

地铁隧道采用大直径泥水平衡盾构进行施工,一次推进完成上、下行区间隧道,这在国内尚属首次。本文以上海轨道交通某标段工程为例,详细叙述了大直径泥水平衡盾构于冻结法加固的土体中进行风井进出洞的施工技术和措施,并取得了良好的施工效果,保证了工程安全和工期要求。     

北京地铁十号线土压平衡盾构土体改良技术应用研究

结合北京地铁十号线一期盾构隧道工程,对土压平衡盾构土体改良技术的应用进行了系统的研究、总结,提出了土压平衡盾构施工的主要问题和施工中采取的主要措施和关键技术,分析了新型泥浆土体改良技术、气泡土体改良技术、泡沫和膨胀土泥浆相结合的土体改良技术等的作用机理和特点,指出了土压平衡盾构土体改良的重要性和目前的研究现状.     

地铁隧道施工过古城墙的地表变形及控制措施

西安地铁二号线区间隧道施工对城墙等国家级文物的影响是隧道安全施工中需要解决的关键问题之一。文章针对该地铁工程介绍了上行线隧道盾构下穿护城河及城墙时的地表变形控制措施和施工变形监测方案,并对监测结果进行分析。分析结果表明,隧道盾构施工中,造成地表沉降是多种因素共同作用的结果;盾构施工过程中,注浆必须同步、足量且补浆及时;随着盾构的推进,需要不断调整土压力以适应地层的变化。隧道已经安全通过城墙,表明所采用的地表沉降控制措施和监测方案是合理可行的。     

Survey of R&D in PRT systems

A survey of research and development in advanced transit has been made by Chalmers University of Technology in Gothenburg in cooperation with Trans21 in Boston. Summary findings are reported for fourteen academic research programs and ten development programs for PRT. An earlier version of this paper was presented at the International Conference of PRT and other Emerging Systems held in Minneapolis in 1996.     

The Impact of Container Type Diversification on Regional British Port Development Strategies

Abstract

Despite a concentration of container traffic in the southeast of the UK over the last few decades, regional ports are attempting new development strategies to capture or retain specific traffic segments. These include intra-European short-sea traffic and a potentially increasing feeder market. These trends are reflected in the movement of different container types, which result in a number of planning challenges related to changing infrastructural and operational requirements. This paper uses highly disaggregated data on container type movements to address three issues that can inform these planning challenges. First, the imbalance of trade resulting in empty container repositioning; second, the requirement for gauge-cleared rail routes to cater for the increasing proportion of high-cube containers; and third, the specialisation of European short-sea traffic at secondary UK ports. The results reveal the disproportionate repositioning of empty containers at Scottish ports and the importance of 45?ft, high-cube and pallet-wide containers at regional ports, highlighting their focus on intra-European short-sea traffic and raising difficulties relating to their lower quality of landside infrastructure (particularly rail) in comparison to the large south-eastern ports. The potential repercussions on hinterland infrastructure development raise questions about both public and private sector responses to regional port development.     

Modular route bus design – A method of meeting transport operation and vehicle manufacturing requirements

This research examines the problem of route bus specification and vehicle manufacturability. In order for bus operators to provide transport services, a range of vehicle configurations must be available from bus manufacturers, generating variety which has a negative impact on the manufacturing process. Larger part inventories, uncontrolled labour tasks and more troublesome maintenance are known impacts of this variety. This research identifies the functional necessities in route bus interior design and reduces the problems in bus manufacture and operation caused by specification diversity by proposing a modularised system of bus design. In particular, it makes recommendations as to how bus configuration should be carried out, ensuring an optimum mix of operational and manufacturing needs:

• 1.Determine user needs before the bus specification process.
• 2.Designs to be developed by the manufacturer in response to user needs.
• 3.This design should be standardised where possible, as suggested by the user needs.
• 4.Where user needs dictate product variations, apply a mass customisation approach to accommodate these needs.

The recommendations are communicated in design proposals for a modular bus interior, demonstrated by four cases designed to meet the present status quo of bus interior design and predictions for the future of the field.     

管道风险分析指数评分法中分值调整初探

管道风险分析指数评分法中重要步骤之一就是确定影响管道事故因素的权重,各个管道风险因素在整个管道事故中所占的权重是不相同的。针对目前管道风险分析指数评分法基本假设之一（各因素的分值范围都是0～100分）,为了更加客观、准确、合理地反映各个风险因素对于管道事故的影响程度,提出并论述了依据层次分析法的数学逻辑性进行综合计算得出管道风险因素的权重,然后对评分法中各个因素的最高分值,根据其权重不同进行相应调整,从而增强评价者对风险因素的认识和评判能力,提高管道风险评价结果的准确性。     

Determinants of modal choice in freight transport

In the next few years, exciting developments in the field of freight transport are likely to occur. The Channel Tunnel will be perceived as giving railways much greater distance of operation, compared to the current train ferry to/from Great Britain. The further development of swap-body technology will allow easier modal transfer and the creation, in 1992, of a single market in Europe will transform the pattern of trade. All of these are likely to have significant impacts on modal choice, and hence modal split, in freight transport. Reappraisal by many firms of the modes of transport used is likely but will it result in a net transfer of freight from road to rail and, if so, to what extent? To answer such questions, an accurate and reliable method of predicting modal split is required. Research in the past has concentrated on the development of modal split models based on generalised costs. These fail to explain adequately the prevalence of road freight in the UK. From surveys of freight managers within industry, it is clear that models to date rely too heavily on the economic cost factor and too little on behavioural factors (Jeffs 1985). This paper derives from a recent study of freight transport modal choice from the standpoint of the transport decision-maker within the firm. It attempts to shed light on the actual parameters which should be incorporated into a modal split model. Many variables appear to exert an influence on modal choice decision-making process. However, it is possible to categorise them into six main groups, namely: customer-requirements; product-characteristics; company structure/organisation; government interventions; available transport facilities; and perceptions of the decision-maker him/herself. It is the interactions and inter-relationships between these which ultimately determine freight modal split. This study has shown that the relationship between the outcome of the transport decision process and the values of particular determinants of modal split is not straight-forward, due to the complexity and variety of interactions involved. Perhaps one of the main reasons for researchers' failure hitherto to develop a successful modal-split model has been the preoccupation with techniques that rely on the development of common metric (e.g. generalised cost), which has led to the exclusion of some important explanatory variables along quite different dimensions. Another important issue concerns the appropriate level of aggregation. In order not to reduce the explanatory power of the key variables, it is important to work at a disaggregate level, although this does make substantial demands on data. The use of factor analysis enables both the aggregation of information without loss of behavioural reality and the specification of variables in terms of a common metric. In conclusion, freight transport has usually been examined within too narrow a framework. It must be placed firmly within the context of the total industrial process. The demand for freight transport is directly influenced by the level, composition and geographical distribution of production and consumption activities. Freight flows are complex and so it is highly unlikely that a universal mode-choice model can ever be developed. Future research should, therefore, be directed towards developing partial models in response to specific needs of those involved in decision-taking in the freight sector.     

A century of evolution of the accessibility concept

The concept of accessibility has acquired numerous meanings along multiple dimensions during the century of its evolution. This essay argues for the salience of two dimensions: application-based and definition-based. In its application, accessibility has incorporated positive and normative dimensions which have varied in prominence over time. In its definition, accessibility has varied between a mode of evaluation incorporating measured mobility and proximity, on the one hand, and a predefined market basket of urbanist improvements to transportation and land use systems, on the other. Advocates of the accessibility shift should emphasize both the measured approach to accessibility and accessibility’s normative side.     

Optimization of bus stop locations for improving transit accessibility

A mathematical model is developed in this paper to improve the accessibility of a bus service. To formulate the optimization model, a segment of a bus route is given, on which a number of demand entry points are distributed realistically. The objective total cost function (i.e. the sum of supplier and user costs) is minimized by optimizing the number and locations of stops, subject to non‐additive users' value of time. A numerical example is designed to demonstrate the effectiveness of the method thus developed to optimize the bus stop location problem. The sensitivity of the total cost to various parameters (e.g. value of users' time, access speed, and demand density) and the effect of the parameters on the optimal stop locations are analyzed and discussed.     

Productive efficiency and ownership of urban bus services

The established ownership mix of urban bus operations in Australia provides a unique opportunity to investigate the productivity differences between public and private bus service supply. Using duality theory in economics which links economic indices of factor productivity to the cost structure of a firm, we develop empirical measures of total and partial productivity of inputs, and adjust the differences for the effects of ownership status and operating environment. The evidence supports the notion that private supply of public passenger transport in general has performed more efficiently in the past than public supply, although the differences in productivity need not continue in the future.