桥梁桩基施工技术应用研究

文章对桥梁桩基施工技术的应用进行研究,主要介绍桥梁桩基施工的重要性,阐述桥梁桩基施工流程,总结桥梁桩基施工技术优缺点及桥梁桩基施工技术优化策略。希望通过相关研究,为桥梁桩基施工技术的实际应用提供一定的参考。     

桥梁桩基施工常见质量问题及处治措施

文章根据桥梁桩基施工实践,分析了桥梁桩基施工中的常见质量问题,提出了针对性的处治措施,为施工企业的桩基施工工作提供经验借鉴。     

桥梁桩基施工中的常见问题及处理措施探讨

在桥梁工程施工的过程当中,桥梁桩基施工是相对比较重要的一个部位,桥梁桩基能够有效分散桥梁上方所承载的压力,并将其转移到桥梁的地基上,以此减少对桥梁的损害。因桩基的施工质量对桥梁工程的整个施工质量会产生最直接的影响,对桥梁的功能、结构、使用寿命等方面有着积极作用,基于此,我们一定要重视桥梁桩基施工的质量问题。但在实际桥梁桩基施工的过程中,在多种不利因素作用和影响之下,会出现很多问题,进而导致桥梁桩基出现质量问题,受到破坏。本文中,笔者对我国桥梁桩基施工过程中的一些关键技术进行了总结,对施工过程中出现的一些问题进行了研究,并对产生这些问题的主要原因进行了分析,最终根据这些原因提出了一些有效的处理对策,旨在提升桥梁桩基施工的整体质量和水平。     

桥梁桩基施工中存在的质量问题及解决策略

桥梁桩基施工质量的好坏直接决定了整个桥梁的稳定性和使用寿命,因此对桩基的施工质量控制成为重中之重。基于桥梁桩基施工中的重要性进行分析,探讨了桥梁桩基在施工中存在的问题,提出桩基施工质量控制优化及问题处理措施,指出在解决施工中存在的问题时,要根据实际施工现场情况来选取施工工艺和相关技术,对各个环节严格把关,从而提高施工质量。     

喀斯特地区桥梁桩基稳定性评价及施工决策优化设计

由于桥梁桩基工程属于地下隐蔽工程,工程质量除受岩土工程条件、基础与结构设计、桩土相互作用、施工工艺以及专业水平和经验等关联因素影响,另外喀斯特地区的地面塌陷,也会降低桥梁基础的稳定性,对桩基施工质量造成破坏。文章通过研究基于模糊算法的六冬水库大桥桩基施工项目实例,提出喀斯特地区桥梁桩基施工决策方法,构建喀斯特地区桥梁桩基稳定性模糊评价模型,优化了喀斯特地区桥梁桩基设计和施工过程,确保了决策的正确性,在提高桥梁基础稳定性和桩基施工质量方面发挥了积极作用。     

地铁隧道施工对附近桥梁桩基的影响及控制措施研究

地铁隧道施工过程中会对附近的桥梁桩基造成扰动等影响,对桥梁结构的稳定性带来一定冲击。文章介绍了桥梁桩基的作用机理,分析了桥梁桩基各部分载荷受力情况,并对引起桥梁桩基形变的主要因素以及桥梁桩基形变的主要模式进行了研究,提出了控制桥梁桩基形变的具体措施。     

山区斜坡桥梁桩基施工策略研究

文章对山区斜坡桥梁桩基的载荷原理进行了分析,并结合桩基附近地质的弱化特点,提出了山区斜坡桥梁桩基施工稳定性控制模型,通过特定试验结果对比、分析和验证了该模型的正确性与可行性。同时,对桩体的弹性阈量以及嵌固深度等进行了细致的讨论,研究其对山区斜坡桥梁桩基施工过程中的稳定性的影响,研究表明,桩基深度以及弹性阈量对山区斜坡桥梁桩基在施工过程中的稳定性均有较大影响。     

某大桥裸露斜坡岩层桩基施工

某桥梁部份桩基位于直接裸露的岩面上,且岩层的倾斜面度达到20度左右,本桩基的施工,为其它相似类型桥梁的桩基施工提供了参考和借鉴。     

岩溶强发育区桩基施工技术研究

针对柴河特大桥岩溶强发育区桩基施工特点,以12#主墩桥梁桩基施工为例,对岩溶强发育区桩基施工方法及特点进行阐述,重点对地质核查、施工准备、外钢护筒设置和冲击钻孔施工等流程进行系统说明。研究成果为岩溶地区桥梁桩基施工提供了参考。     

贺巴高速公路桥梁桩基钢筋笼定位施工技术分析

桩基工程属于高速公路桥梁施工过程中的重要组成部分,对提高桥梁的质量和承载力有着至关重要的作用。在针对桩基进行施工的过程中,一般多采用钻孔灌注桩的施工模式,虽然该模式可以大幅提高桥梁施工质量和施工效率,但是在实际的施工过程中可能会导致桥梁桩基的钢筋笼产生一定的位置偏移,钢筋笼位置的偏移会对后期的施工进度产生很多不良影响。鉴于此,文章结合施工实例,针对钢筋笼偏移情况制定相应的解决策略,以提高桥梁桩基施工效率和施工质量。     

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.     

Inland waterways—their role and significance in European transport

Summary

1) Western Europe has a navigable waterways‐network of about 19,000 kms. For the coming decades, however, about 40 percent of the length of these waterways has a very limited relevance, because of the small capacity of the barges that can pass along them.

2) Of the different types of barges the majority are the self‐propelled type. The importance of the pull‐towed barges is declining quickly, whereas the push‐towed barges are on the upswing.

3) The relative importance of inland shipping in comparison with rail transport is far from uniform. In The Netherlands inland shipping is dominant. On the other hand, in France, this mode of transport has only 30 percent of the total number of tons transported by inland shipping and railways together.

4) May the relative importance defer, there is a strong resemblance between the types of goods that are transported via the waterways with crude and manufactured minerals as well as building materials ranking high. In general, inland shipping is primarily involved in the transport of basic products and is of vital importance to the functioning of the West‐European economy.

5) The rather complicated legal regime of the waterways in Western Europe is certainly not the only reason why the integration in the transportation sector of the European Communities hardly moves on.

A fundamental discussion about the basic conceptions of the transport policy in the Common Market is unavoidable before real progress can be made. The entrance of the United Kingdom into the European Community may give an opening on this point.

6) Life goes on, with or without transport‐integration. Inland shipping moves forward too, paying for the use of infrastructure or not.

The general trends in transport support the expectation that the relative importance of inland shipping will increase in the coming decades. The increase in size of shipments and transport distances works in favour of this mode of transport. Besides this, inland shipping still has many possibilities to improve its productivity.

7) The future of inland shipping will be found in bulk transport and the transport of general cargo that has a volume per destination that goes far beyond the quantities for which the container or comparable types of transport units are better suited.     

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。     

Induced traffic: what do transportation models tell us?

Mathematical models of transportation systems have played a prominent role in transportation planning throughout the world since the 1960s. These models are hypotheses of how people use transport systems. They provide a means of extrapolating the necessarily limited empirical evidence of how road users respond to changes in the road system. However, it needs to be recognised that these extrapolations rely for their validity on the realism of the underlying theories; transportation models can only tell us about the relationships actually built into them.This paper reviews the limited number of studies undertaken mainly in the UK in which calibrated transportation models have been used in a systematic way to give some insight into the relative importance of the various components of induced traffic. These studies include analyses of the effects of road schemes using: a theoretical single link model; conventional four-stage transportation models of Cardiff and Belfast; elasticity models in Cardiff, Belfast, West London and Norwich; land-use interaction models in Leeds, Bilbao, Dortmund; and a model of land-use effects in Norwich. The results tell us two things: (a) the scale of the various elements of induced traffic, and (b) the implications for the economic benefits of road schemes.     

Transport emissions and travel behaviour: A critical review of recent European Union and UK policy initiatives

There are clear signs of a shift in the UK transport policy in response to concerns about the environmental impacts of road transport and anxieties about the implications of the projected future growth in demand.Much of the framework of UK transport policy is now determined at the overall European Union level. To date most European legislation and policy proposals have been concerned with reducing the specific externalities associated with the transport sector, with none of the measures involved likely to have more than a marginal impact on the growth in demand. The emerging research evidence suggests however that the private costs of car use in Europe may fall substantially short of its total social costs and there is an important emerging policy debate about how this gap might be closed.The UK has introduced a policy package designed to reduce the growth of car travel and its environmental impact, within which land-use planning measures feature prominently. The land-use policies, which to some extent represent a reassertion of many traditional UK planning policies, include: an emphasis on focussing new development in urban areas, increasing residential densities, strengthening the role of existing centres and improving provision for walking and cycling.A number of factors will constrain the effectiveness of the package in practice. There are also concerns about its impact on key environmental objectives, including air quality. There are important questions too about the welfare effects of increasing densities and about the wider impacts of the package on economic efficiency.     

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.     

The quality of survey data: Telephone versus face-to-face interviews

Those designing surveys and producing data have always been concerned about its quality. The increasing stringency of the financial constraints which affect public authorities and the increased scope of involvement in the regulation of urban travel has led us to pay even greater attention to the quality of data. This issue is frequently covered in the literature on survey methods. However, comparisons between different survey methods are more rarely conducted. The decision to conduct such an analysis is partly the result of the development of telephone use to the detriment of other survey modes in many countries and also the development of Computer-Aided Telephone Interviewing (CATI) which facilitates the running and monitoring of the survey.This paper examines several aspects of this question in order to compare the performance of telephone and face-to-face interviews. The first aspect is the representativeness of the sample, and therefore relates mainly to the issue of nonresponses and the choice of a sample base. The second concerns the accuracy of the information and involves the choice of a survey area and the recording of all trips, including short-distance travel. Finally, the quality of data is obviously determined by the quality of the responses given by those interviewed.The answers we give frequently depend on the objective of the surveys, which leads us to put forward a table which summarizes the performance of telephone and face-to-face interviews on the basis of the main objective of the survey. Broadly, the telephone seems to be the favoured tool for surveys in the area of transport planning and surveys which aim to provide data for forecasting models, mostly on the grounds of cost. However, face-to-face techniques are often preferred for surveys which aim to discover and analyze the factors which explain individual travel behaviour.     

A new approach for modeling of Fundamental Diagrams

According to the intra-vehicle interaction, a traffic flow can generally be divided into three homogeneous states (1) that of free driving, (2) that of bunched driving, and (3) that of standing. The parameter describing the state of free driving is the desired speed, for the state of bunching it is the intra-vehicle gaps (time headway) within the convoy and the mean speed of the convoy, and for the state of standing it is the maximum jam density. These are the most essential parameters which do not depend on the actual traffic situation.This paper introduces a new model which considers the Fundamental Diagram (equilibrium speed–flow–density relationship) as a function of the homogeneous states. All traffic situations in reality can be considered as combinations of the homogeneous states and therefore can be described by the essential parameters mentioned above. The non-congested (fluid) traffic is a combination (superposition) of the states of free driving and bunched driving, the congested (jam, stop, and go) traffic is a combination of the states of bunched driving (go) and standing (stop). The contribution of the traffic states within the differently congested traffic situations can then be easily obtained from the queuing and probability theory. As a result, Fundamental Diagram in all equilibrium traffic situations is derived as simple functions of the essential parameters.According to the new model the capacity of freeways and rural highways can be determined by measuring the essential parameters. This is much easier than measuring the capacity directly.Furthermore, the probabilities of the various traffic states can be obtained from the new model. This leads to new possibilities in real-time controlling and telematics.The new model is verified by comprehensive measurements carried out on freeways and rural highways in Germany.