粉砂性土层中盾构施工措施的优化改进

文章以杭州地铁一号线隧道工程为依托,分析了土压平衡盾构在粉砂性土层中推进易碰到的问题,并进行了相应的改进;针对实际掘进中盾构刀盘和螺旋机叶轮的磨损规律,通过试验对比,提出了切实有效的耐磨加固措施,并取得了很好的效果;通过对原泡沫系统的不足进行优化改进,使泡沫系统简单化、成本节约化;针对不同大小的推进力进行试验,得到了该地层施工中的最优推进力。通过一系列优化改进措施,本工程得以安全、高效地完工,可为今后粉砂性土层盾构隧道施工提供借鉴。     

复合地层盾构刀具磨损控制技术研究

文章以杭州地铁2号线杭发厂站—人民路站盾构区间隧道工程为背景,首先对盾构穿越上软下硬复合地层段的刀具磨损情况进行了分析,揭示了刀具严重磨损所导致的一系列施工异常现象,包括盾构掘进参数异常、盾构出土异常、地表严重沉降等;其次,针对盾构刀具非预见性严重磨损的工况,提出了地基加固结合常压换刀的处理方法,以及后续盾构掘进过程中土体改良、设备配置优化、参数控制等措施。结果表明,通过对复合地层的盾构施工措施进行优化,刀具磨损量控制在允许范围内。     

盾构掘进参数对地表沉降的影响分析

盾构法作为地铁隧道施工的一种主要施工方法已在我国得到广泛的应用,由施工引起的地层移动和地表沉降是盾构隧道设计和施工中备受关注的问题.文章以深圳地铁5号线洪浪-兴东盾构区间下穿广深高速公路立交桥隧道施工为工程依托,通过数值模拟和现场监测,对影响地表沉降的掘进参数进行了模拟分析.计算结果表明,地表下沉与盾构掘进参数密切相关,适当加大注浆压力能有效控制地表沉降;同时,土舱压力与土体原始侧向压力接近时地表沉降量最少.实测地表沉降与掘进参数的关系表明,当注浆量一定时,地面沉降随土舱压力的增加而减小;地表沉降随着注浆量及注浆压力的增大而减小.     

杭州地铁盾构隧道掘进对建筑物影响的实测分析

文章基于杭州地铁1号线某区间盾构隧道下穿建筑物工程实例,对双线盾构隧道施工过程中引起的建筑物和地表沉降进行了现场监测,并结合盾构掘进系统的数据,对建筑物和地表的实测沉降数据进行了分析,研究了双线盾构隧道掘进施工引起不同位置、不同结构建筑物的沉降规律。结果表明:盾构施工过程中通过控制注浆量和排土量,能有效地控制建筑物的沉降;建筑物基础底面积越大,监测点的沉降曲线越复杂,越需要严格控制施工进程;建筑物离隧道轴线的水平距离越近,监测点的沉降规律和轴线上方地表的沉降规律也越接近。     

泡沫剂对土压平衡盾构主要掘进参数的影响研究

为实现土压平衡盾构快速高效掘进,文章依托厦门地铁2号线3标湿地公园站—五缘湾站区间盾构施工,进行盾构主要掘进参数的影响因素研究,分析了泡沫剂参数与盾构掘进参数的内在关系。通过4种泡沫剂的室内配比试验,并结合现场试验,研究泡沫剂浓度、气液比和泡沫注入比对改良土体的内摩擦角和容重的影响。结果表明,泡沫剂浓度增大1%,渣土内摩擦角减小约2.43°;泡沫剂各参数对刀盘扭矩影响程度是泡沫浓度泡沫流量膨胀率,对盾构推力影响程度是泡沫浓度膨胀率泡沫流量,泡沫浓度对两个掘进参数的影响都最大。当采用改变泡沫系统参数来改善掘进状况时,优先选择改变与掘进参数具有显著线性关系的泡沫浓度,来控制盾构推力和刀盘扭矩达到合理的数值范围,保证盾构安全、顺利掘进。在该工程施工中,泡沫浓度每提高1%,盾构推力平均减小约1 710 kN,刀盘扭矩平均减小约316 kN·m。     

复合式土压平衡盾构机在高强度硬岩中的掘进技术分析与研究

硬岩局部侵入地铁隧道开挖断面,往往对盾构顺利掘进提出较大挑战。盾构通过硬岩段时存在的主要问题是滚刀非正常磨损严重,开挖系统综合性能大大降低,造成推进参数异常、贯入度小、掘进速度极低等问题。文章依托深圳地铁9号线工程,对复合土压平衡式盾构掘进通过高强度花岗岩地层时遇到的主要问题和原因进行了分析,提出了应对措施,通过合理配置刀具、及时更换刀具以及合理确定掘进参数确保了盾构安全顺利通过硬岩段。     

深圳地铁11号线大直径盾构适应性设计

由于机车提速的需要,城市地铁隧道采用大直径盾构施工是未来的发展趋势,深圳地铁11号线在国内首次采用φ6.98 m大直径土压平衡盾构施工。文章针对深圳地铁11号线11301标段盾构施工过程中所遇到的球状风化体区间掘进难度大、软弱不均地层盾构掘进姿态难控制及软粘土地层易引起刀盘结泥饼等三大难题,从主驱动配置、刀盘刀具设计、盾体设计、螺旋输送机设计及碴土改良系统设计等方面对盾构进行了针对性的适应设计,并提出了大直径盾构设计优化建议,能够为大直径盾构设计及其应用起到指导作用。     

盾构隧道下穿既有线路施工参数控制及沉降分析

盾构隧道掘进施工是一项复杂的工程,适用于对已有线路的盾构隧道下穿施工,整个工程对施工环境的要求较高。本文主要讨论南宁地铁三号线中的金湖广场站至埌西站区间的盾构隧道下穿施工工程,其中,对盾构隧道掘进施工的参数问题做了基本的讨论,对具体参数的调整和修正进行了分析。此外,对盾构隧道掘进施工工程中的监测问题也进行了详细的论述和说明。工程满足运营要求,完工后对已有线路影响较小,希望本文能为类似工程提供借鉴和参考。     

富水砂卵石地层土压平衡盾构长距离快速施工技术

成都地层以地下水位高、卵石含量多及硬度大、漂石含量高且局部密集成群著称,是否适合盾构法施工或采用何种类型盾构施工.一直存在争论.文章以成都地铁一号线盾构4标左线隧道施工为例,从盾构选型、掘进参数选择、快速换刀、建筑物保护和监控量测等方面.对土压平衡盾构在富水砂卵石地层中的快速掘进技术进行了初步探讨,并结合地铁一号线施工中存在的问题,对地铁二号线盾构选型和施工提出了相应建议.     

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.     

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.     

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.     

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。     

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.