建筑垃圾再生材料在底基层的应用

本文以某二级公路改扩建为依托,研究在一定剂量的水泥粉煤灰作用下,将建筑垃圾再生材料与碎石进行掺配,设计5组配合比,分别进行原材料试验、击实试验与7d无侧限抗压强度试验,研究不同建筑垃圾再生材料掺量在底基层中的应用。研究结果表明:随着建筑垃圾再生材料掺量的逐渐增多,原材的压碎值达到34.7%,混合料最大干密度降低,最佳含水率升高,7d无侧限抗压强度低至2.3MPa,因此不推荐将建筑垃圾再生材料直接应用于底基层实际工程中。将建筑垃圾再生材料与碎石进行一定比例的掺配可以达到实际工程的应用指标,且可以大大降低施工原材料成本,对能源的可持续应用有重要意义。     

击实试验中最大干密度和最优含水率影响因素分析

击实试验模拟施工现场夯实原理,通过标准化击实仪和规范化操作对土料施加荷载使之压实,并在此过程中确定施工所需最大干密度和最优含水率,为实际施工提供重要的依据。鉴于此,对击实试验过程中最大干密度和最优含水率的影响因素进行了归纳分析,可为公路工程击实试验的实施提供参考。     

建筑垃圾再生砖混材料在路基中的应用研究

通过对建筑垃圾再生砖混材料的原材料和无机稳定混合料的性能试验,文章分析了再生材料的不均匀性、最大干密度、最佳含水率、CBR值等指标的变化规律,探究其作为路基填料的可行性。结果表明:建筑垃圾再生砖混材料的级配良好,同时吸水率较高,可以配合其他材料改善路基干湿状态;水泥和石灰均可有效提高再生砖混料的CBR值,且水泥稳定时对击实功变化较为敏感;再生转混料的整体性能完全满足规范对路基填料的技术指标要求,可以作为路基填料使用。     

抗疏力固化土的室内击实试验研究

文章通过分析抗疏力固化土室内击实试验和无侧限抗压强度试验,探讨抗疏力固化材料的不同掺量对抗疏力固化土最大干密度和最佳含水量的影响,及其对抗疏力固化土无侧限抗压强度的影响.     

石灰改良土在宁德宁武高速公路工程中的应用研究

结合宁德宁武高速公路A7合同段工程.通过击实、CBR试验和现场试验段施工方法,对石灰改良土的路用性能能及施工工艺进行研究,试验得出了合理石灰剂量、最佳含水率、最大干密度等室内控制指标,并提出合理机具组合、松铺厚度、碾压遍数、碾压速度等施工参数,结论可为工程实践提供有益借鉴.     

建筑废料对改良地基土物理特性试验研究

本文将建筑废料用于改良湿陷性黄土地基。为了研究改良地基土的相关力学分布规律。先进行压实特性试验,将一定天然含水量为12%的湿陷性黄土与建筑废弃物拌合,通过对比不同掺量不同击实次数的湿密度随击实次数的变化情况,确定最佳击实次数为45次。在最佳击实次数条件下,制备高为152mm、直径为116mm的标准试样,进行单轴压缩试验。综合对比无侧限抗压强度与弹性模量二个力学参数,最终确定最优配合比为15%。     

水泥土换填法在粉质砂土路基施工中的应用研究

文章依托某公路路基施工项目,以水泥土换填方案对原路基填土进行改良增强,针对水泥、施工项目现场素土以及掺配好的水泥土进行指标检测;对常规室内击实试验进行优化,通过击实试验对掺配完成0～4 h的水泥土进行对比试验分析,得出符合施工现场状态的水泥土最大干密度;对人工及机械水泥撒布方式的经济成本进行了对比与优选,确定了粉料机撒...     

全风化花岗岩石灰改良土室内试验分析

基于高速铁路对防止路基变形的严格要求,常常需要对用作路基填料的土质进行改良。文章通过对全风化花岗岩生石灰改良土的大量室内试验,研究了改良土在不同掺和比下液塑限的变化,在不同击实条件下最大干密度和最优含水率的确定及影响,以及无侧限抗压强度的影响因素,为花岗岩地段铁路客运专线路基的设计和施工提供参考。     

配比建筑垃圾再生材料大型固结试验分析

本文利用室内大型固结试验,分析了建筑垃圾再生材料三种配比、四种压实度在不同荷载条件下的压缩性质,通过研究不同配比材料的应变与荷载的关系、孔隙比与配比的关系、压缩系数与配比的关系、应变与配比的关系及应变与压实度的关系,得出:建筑垃圾再生材料的变形随着荷载的增大而增大,不同的压实度会使各配比的孔隙比的峰值有所不同,砖渣的含量对建筑垃圾再生材料压缩性能有较大影响,在进行现场施工时,应注意控制砖渣含量。     

隧道花岗岩弃渣水泥稳定基层路用性能研究

文章针对遵秦高速公路隧道花岗岩弃渣的资源化利用以及其在基层应用的可行性等问题,分析了隧道花岗岩弃渣碎石的级配组成、压碎值、针片状含量等物理性能,并通过重型击实试验确定隧道花岗岩弃渣水泥稳定基层(以下简称“水泥稳定弃渣”)的最大干密度和最佳含水率:通过测试强度、回弹模量、抗冻性能以及干、温缩特性等路用性能,并与水泥稳定片麻岩、石灰岩进行对比,优化水泥稳定弃渣的各项配合比。结果表明:隧道花岗岩弃渣碎石的级配良好,水泥稳定弃渣的劈裂强度和7 d无侧限抗压强度分别为0.45 MPa和5.13 Ma,集料种类对水泥稳定碎石的力学性能影响较小:28 d试件冻融循环后抗压强度损失为97%～98%,具有良好的抗冻性:隧道花岗岩弃渣的温缩性能优于水泥稳定片麻岩、石灰岩;当水泥稳定弃渣最佳水泥用量为4%、最大干密度为2.334 g/cm³、最佳含水量为4.8%时,满足基层材料的技术要求。     

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.     

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.     

天然气站往复式压缩机活塞失效分析

针对天然气站往复式压缩机活塞的断裂事故,运用失效分析方法,开展了活塞断口扫描电镜分析、能谱和金相分析。根据断口形貌的电镜和金相观察结果,结合理论知识,分析确定了该活塞发生断裂事故的主要原因,即在特定工况下该活塞的材料缺陷是造成断裂的主要因素。     

中国城市道路规划方位性问题研究

文章结合中国的传统建筑文化理念和现代科学原理,从历史文化、能源节约、环境保护、房地产定价、交通安全等多方面分析研究了城市道路在规划和设计时所应遵从的定向规则。     

Predicting queue variability to enable analysis of overload risk

ABSTRACT

Predicting the risk of traffic demands and delays exceeding critical limits at road junctions, airports, hospitals, etc., requires knowing how both mean and variance of queue size vary over time. Microscopic simulation can explore variability but is computationally demanding and gives only sample results. A computationally efficient approximation to the mean is used in many modelling tools, but only empirical extensions for variance in particular situations have been available. The paper derives theoretical formulae for time-dependent and equilibrium variance, believed to be novel and to apply generally to queues covered by the Pollaczek–Khinchin mean formula, and offering possible structural insights. These are applied in an extended approximation giving mutually consistent mean and variance estimates with improved accuracy. Tests on oversaturated peak demand cases are compared with Markov probabilistic simulation, demonstrating accuracy (R^2?>?0.99) for typical random, priority-like (M/M/1) and traffic-signal-like (M/D/1) queues. Implications for risk analysis, planning and policy are considered.     

Planning guidelines for metro–bus interchanges by means of a pedestrian microsimulation model

The big paradigm for cities nowadays is to study the movement of pedestrians at the interface between metro and bus systems – metro–bus interchanges. When these interchanges are not well designed, walking is inefficient and can be unsafe for pedestrians. This paper analyses, by means of a pedestrian microsimulation model, metro–bus interchange spaces in order to propose planning guidelines for the city of Santiago de Chile. Specific objectives are (1) to identify the variables that provide efficiency and safety in those spaces; (2) to simulate different scenarios using the pedestrian simulation model LEGION; (3) to propose planning and design guidelines for pedestrian spaces at metro–bus interchanges; and (4) to contrast the recommendations in the recently opened terminal station on Line 1 of Metro de Santiago: Los Dominicos Station.     

生命大过天

文章介绍了广西壮族自治区公路管理局开展专项行动,治理以桥梁为重点的交通基础设施安全隐患的情况,针对在役桥梁、在建桥梁和农村公路桥梁存在的安全隐患提出了相应的治理措施。