考虑施工过程的大直径圆形地下连续墙计算研究

文章以平南三桥北岸地下连续墙为工程背景,研究施工过程对地下连续墙设计的影响。结果表明,是否考虑施工过程这一因素对地下连续墙的受力和变形有显著影响。为确保结构安全,建议采用增量法考虑施工过程对地下连续墙进行设计计算。     

天平线关山隧道涌水量预测技术研究

在富水位地区建设特长隧道中通常会发生涌水灾害,因此准确预测隧道涌水量能科学指导隧道的设计和施工.新建关山隧道处于关山褶皱带,地下水循环强烈,岩体节理发育,对工程施工的安全影响较大.基于此,文章对关山隧道水文地质情况进行分析,采用不同涌水量计算方法对隧道各研究区段涌水量进行预测.通过对比分析,发现地下径流模数法预测结果较...     

特大型地下洞室群施工期通风技术研究及应用

地下洞室常采用新奥法或矿山法施工,掌子面爆破产生的污染物影响施工人员的人身安全和职业健康,同时也制约着洞室的开挖进度。文章依托白鹤滩水电站工程,提出了"三结合"、"分期设计"的地下洞室群施工期通风系统规划和设计理念,构建了三维非稳态湍流场模型,研究了复杂地下洞室群开挖期通风散烟特点和规律,提前规划并实施了与各主要洞室贯通的专用排风洞,形成了一套高效节能的"进+排"通风系统,使用变频风机在最大程度利用自然通风的基础上实现机械通风的最优效果。数值计算和现场污染物浓度测试结果表明:白鹤滩水电站地下洞室群施工期气流组织顺畅,专用排风竖井区域空气流速远大于洞室周边区域,污染物逸散路径为掌子面—排风竖井—专用排风平洞;通风15 min后,爆破产生的污染物即可全部排出洞外,效果良好。     

山西省高速公路水环境污染及其防治措施探讨

文章分析了高速公路在建设和运营过程中对地表或地下水环境的影响,并相应的提出了高速公路建设期和运营期水环境污染防治措施,为山西省高速公路水环境安全相关研究的进一步发展和完善提供参考和借鉴。     

上海市轨道交通9号线宜山路站基坑施工技术

上海市轨道交通9号线宜山路站为地下4层岛式车站,是在缺失⑥层土的地质情况下施工的。叙述了在超深地下连续墙施工和Z1区基坑开挖施工过程中采用的多种创新技术和必要的技术措施,以确保车站施工顺利进行;通过对基坑变形和降承压水等方面的有效控制,确保了基坑和周边环境的安全。     

城市道路交通安全预测与评价方法研究

为提高城市道路交通安全性,确保车辆通畅、安全运行,对城市道路交通安全预测与评价方法进行研究。首先,分析影响道路交通安全的相关因素;其次,解读研究过程中所涉及的理论,通过构建安全预测模型、实施指标评价方法,提高城市道路交通安全预测与评价结果的准确性;最后,分析车辆行驶轨迹获取方式,以及车速离散度、紧急加速或减速行为对交通安全造成的实际影响。研究取得预期成果,可实现对交通安全的有效预测与评价,能为城市道路交通安全管控提供可靠参考。     

浅析煤矿采矿工程中巷道掘进支护技术的应用

在煤矿采矿工程中,巷道掘进支护技术的应用对于确保采矿工作安全和提高生产效率至关重要。本文对煤矿巷道掘进支护技术的具体应用进行论述,探讨永久性、锚杆以及棚式等不同类型支护技术的应用,并在此基础上,结合巷道掘进支护工作的特点,进一步分析巷道掘进支护技术的应用要点,旨在为煤矿采矿工程的巷道掘进支护提供一定的参考,进而为开采工作的安全进行提供可靠保障。     

平南三桥地下连续墙钢筋笼吊装安全管理研究

钢筋笼吊装工程作为危险性较大的工程,是地下连续墙顺利施工的关键,更是项目安全管理的重点和难点。文章主要研究了广西荔浦-玉林公路平南三桥地下连续墙钢筋笼吊装过程中的重点和难点问题,用LEC法则对危险源进行了分析,提出了相应的安全管控措施和方法,并阐述了实际应用情况,以期为其他类似工程提供参考借鉴。     

地铁隧道暗挖施工对既有管线的变形影响规律及其控制技术

城市地铁隧道施工中,有效保证邻近管线的安全是工程的难点之一。文章以西安地铁三号线通-胡区间为研究背景,采用FLAC数值模拟,得出了地铁隧道暗挖施工对邻近平行及垂直于隧道轴线的地下管线变形影响的规律;通过分析,预测了地铁穿越地裂缝施工后管线的变形趋势,并提出了地铁隧道下穿f4地裂缝的技术措施,以及地铁暗挖施工中对邻近管线的保护措施。工程实践表明,文章提出的控制措施合理有效。     

大型地下互通式立交型式选择和路线标准研究

文章通过对地下和地面立交对比分析,给出了三路和四路地下立体交叉的几种立交型式建议;并从造价和行车安全的角度,给出了地下立交分岔隧道的部分路线标准确定方法。在地下隧道立交的选型中,应尽量选取少交叉口、少叠交层次和行车视距较好的型式。在路线标准的选择中,尤其要注意满足运营速度下的停车视距,以保障行车安全。在考虑安全因素的同时,经济性和工程造价也是决定隧道型式和路线标准的重要因素。     

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.     

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.     

Real-world gaseous and particle emissions of a Bi-fuel gasoline/CNG Euro 6 passenger car

The objective of the present study is the assessment of the environmental impact of a bivalent (bi-fuel) vehicle, running either on gasoline or compressed natural gas (CNG). To that aim, a Euro 6 passenger car was tested under various real-world driving conditions. In order to cover the full range of conventional powertrains currently in the market, the tests were also repeated on a Euro 6 diesel passenger car. Both cars were driven in two routes, the first complying with the regulation limits and the second going beyond them. Carbon monoxide (CO), nitrogen oxides (NO_x) and particle number (PN) emissions were recorded using a Portable Emissions Measurement System (PEMS). Apart from the aggregated emission levels, in g/km, the exact emission location along the route was also assessed. Natural gas proved beneficial for CO and PN emissions, the level of which always remained below the respective legislation limits. On the other hand, under the dynamic driving conditions with gasoline, the relevant limits were exceeded. Cold start, occurring at the beginning of the urban part, and motorway driving were identified as major contributors to total emissions, especially in gasoline mode. However, the application of natural gas was associated with a penalty in NO_x emissions, which were significantly increased as compared to gasoline. Local peaks within the urban part were identified in CNG mode. In any case, the diesel vehicle was by far the highest NO_x emitter.     

Seaport performance analysis using robust non-parametric efficiency estimators

Abstract

Seaport services have been developing year on year, playing an increasingly important role in the economy and the transportation markets of each country. This increases interest in measuring their performance. This paper evaluates the performance of a set of European seaports by means of robust non-parametric approaches. Using order-m and bootstrap procedures, the major problems of traditional data envelopment analysis and free disposal hull methods – concerning noise, presence of outliers and the ‘curse of dimensionality’ – are overcome. With this study considerable levels of inefficiency were found in the European seaports sector.     

Bicycle parking: a systematic review of scientific literature on parking behaviour,parking preferences,and their influence on cycling and travel behaviour

ABSTRACT

Cycling is experiencing a revival in many cities. Research has focused on the determinants of cycling – in particular the role of the built environment and road infrastructure. Bicycle parking has received little attention – even though bicycles are parked most of the time. This article reviews the scientific literature on bicycle parking and identifies existing gaps in research and knowledge. The review analyses 94 peer-reviewed papers identified through a search in Scopus and Web of Science, in December 2017. The annual number of papers increased 15-fold between 1995 and 2017. Overall, the level of evidence on the importance of bicycle parking is limited. The majority of studies are based on cross-sectional data with the presence of parking as a binary independent variable. Most studies focus on bicycle parking at public transport stops and at work places. Few studies report on bicycle parking throughout cities, and hardly any on parking at residential locations. Bicycle parking supply and quality appears to be a determinant of cycling for current and potential cyclists. Our findings can serve as input for an evidence-based debate on the role of bicycle parking. For practitioners, our research supports investment in bicycle parking, but acknowledges that a proper evaluation of such initiatives needs to be conducted to increase the level of evidence.     

Multilevel analysis of daily time use and time allocation to activity types accounting for complex covariance structures using correlated random effects

In this paper multilevel analysis is used to study individual choices of time allocation to maintenance, subsistence, leisure, and travel time exploiting the nested data hierarchy of households, persons, and occasions of measurement. The multilevel models in this paper examine the joint and multivariate correlation structure of four dependent variables in a cross-sectional and longitudinal way. In this way, observed and unobserved heterogeneity are estimated using random effects at the household, person, and temporal levels. In addition, random coefficients associated with explanatory variables are also estimated and correlated with these random effects. Using the wide spectrum of options offered by multilevel models to account for individual and group heterogeneity, complex interdependencies among individuals within their households, within themselves over time, and within themselves but across different indicators of behavior, are analyzed. Findings in this analysis include large variance contribution by each level considered, clear evidence of non-linear dynamic behavior in time-allocation, different trajectories of change in time allocation for each of the four dependent variables used, and lack of symmetry in change over time characterized by different trajectories in the longitudinal evolution of each dependent variable. In addition, the multivariate correlation structure among the four dependent variables is different at each of the three levels of analysis.     

从"神经末梢"到"国际枢纽"——十六大以来广西交通发展综述

文章总结了党的十六大以来广西交通发展取得的成绩,指出广西交通正在从"神经末梢"发展为"国际枢纽",为广西经济社会发展提供了重要支撑。     

Increasing urban tram system efficiency,with battery storage and electric vehicle charging

This paper examines the possible placement of Energy Storage Systems (ESS) on an urban tram system for the purpose of exploring potential increases in operating efficiency through the examination of different locations for battery energy storage. Further, the paper suggests the utilisation of Electric Vehicle (EV) batteries at existing Park and Ride (P&R) sites as a means of achieving additional energy storage at these locations. The study achieves this through MATLAB modelling utilising captured GPS data and publically available information. This study examines the scenario of uni-directional substations with no interconnection between the overhead catenary for both directions of travel, and discusses the trade-offs between ESS size and required current limits.The results show the savings in both energy and basic CO₂ emissions alongside the discussion of Return on Investment (RoI) that can be achieved through the potential installation of ESS at identified ideal locations along the tram network. Moreover, this may be extended to the use of EVs as stationary ESS sited at the existing P&R facilities. Further, the model may also be used to inform future infrastructure upgrades and potential improvements to air quality within urban environments.