西安城墙在地铁建设与运营中的保护措施分析

西安地铁已建和在建的地铁线路多次穿越西安城墙及护城河,如何保证古城墙在地铁建设和运营期间的安全成为较为突出的问题。结合城墙的自身结构问题与工程地质情况的特殊性,通过对比分析相关工程资料和文献,指出:施工阶段,双线分离规划线路是盾构安全下穿城墙的重要前提,合理的土仓压力和注浆参数加之连续施工是盾构安全下穿最主要的主动防范措施,城墙地基土层注浆加固加之门洞钢架支护是盾构安全下穿必要的被动防范措施;运营阶段,采用钢弹簧浮置板道床可以明显减小地铁列车穿越城墙时引起的振动,保证地铁运营期间古城墙的安全。     

富水半成岩砂岩地层地铁车站深基坑变形监测与数值模拟分析

以兰州市某地铁车站深基坑为例,研究第三系富水半成岩砂岩地层条件下桩撑支护结构深基坑的变形规律。通过对围护桩体水平位移、钢支撑轴力、地表沉降等实测结果进行分析,对基坑开挖过程进行数值模拟,将数值计算结果与实测结果进行对比研究基坑的变形规律。监测结果与数值分析表明:桩体变形呈现出两头小中间大的"弓型"变形特征,围护桩水平位移最大值发生在开挖面附近;正常施工下地表沉降形态为凹槽形,若围护桩间出现明显漏水、漏砂现象时为三角形;钢支撑轴力跳跃上升并在其下一道支撑架设后受力达到最大;深大基坑工程采用钻孔咬合灌注桩作为围护及止水结构时,必须确保桩体垂直度,保证桩体施工质量达到设计要求;数值计算结果与实测结果基本一致,数值模拟可为基坑的设计和施工提供依据。     

地铁隧道斜交穿越地裂缝带的纵向设防长度

以西安地铁1号线斜交穿越地裂缝带为工程背景,通过地裂缝活动的大型物理模型试验和有限元数值模拟,对西安地裂缝活动的影响范围和西安地铁1号线隧道穿越地裂缝带的纵向设防长度进行研究.结果表明:地裂缝活动时引起其上盘地层中出现应力降低和下盘地层中出现应力增强现象,且在垂直于地裂缝走向上其两侧地层中应力变化大致呈现出反对称分布特征.隧道设计埋深处地裂缝活动的影响区宽度为30 m,即上盘17.5 m,下盘12.5 m;考虑安全系数时地铁隧道穿越地裂缝带的设防宽度为55 m,即上盘35 m,下盘 20 m.根据地铁隧道与地裂缝带的斜交夹角,确定地铁区间隧道不同夹角斜交穿越地裂缝带的纵向设防长度.研究结果对西安地铁1号线区间隧道斜穿地裂缝带的结构处理及设计具有一定参考价值.     

深圳地铁5号线BT模式下的设计施工一体化实践与探索

研究目的:研究完善BT模式下的设计施工一体化,为BT模式的进一步推广应用奠定基础。研究结论:政府应加强政策引导,进一步落实和完善资质管理制度,通过资质申报同时授予企业勘察设计和施工一体化资质,大力推行工程总承包,提升中国建筑企业的市场竞争力;企业作为市场主体应苦练内功,建立企业设计施工一体化标准体系,培养和造就高素质项目管理人才,整合设计施工资源,实现设计施工零对接,提升企业建设管理能力,积极为BT项目的实施创造条件。     

基于价值工程的南京地铁全效修实施效果评估

南京地铁车辆系统全效修是一种全新的地铁维修模式,其实施效果除了主观的判断外,应用科学具体的理论方法进行客观的评价,从而为选择改善措施提供依据。简要介绍价值工程理论,利用AHP(层次分析法)从人、机、物、法、环五个功能层面分析全效修实施影响因素并构建基于价值工程的评估体系,建立评估模型;通过数据信息收集确定相应的功能系数及成本系数,完成对全效修的价值评估。评估结果表明,全效修实施过程中功能与成本之间匹配程度良好,同时也揭示出推行过程中的薄弱环节,并提出了改进建议。     

天津地铁网络化运营管理的探索和思考

目前天津地铁即将由单线运营转入网络化运营模式,如何充分结合天津地铁线网规划,确定合理的网络化运营模式,确保地铁网络运营的安全、高效,以及如何体现网络化运营模式的社会、经济价值,已成为地铁运营管理面临的新课题。结合天津地铁1号线的运营管理实践经验,分析网络化运营模式对管理体制、运营组织、维修模式、资源共享等方面的要求,为天津地铁网络化运营管理提供思路。     

城市轨道交通多方式组合出行与接驳设施优化

城市轨道交通出行是典型的多方式组合出行,其出行过程不连续、选择需求复杂、出行体验难以捕捉等特征,制约了轨道交通整体出行效率和满意度提升。以南京市为例,分析轨道交通通勤人群的"接入—轨道交通—接出"全过程出行模式特征。考虑接入与接出过程的关联性,构建轨道交通多方式组合出行行为模型,研究各类接驳设施服务对接入和接出方式选择的影响。从轨道交通的竞争方式——全程小汽车通勤出行角度,调查该人群对不同轨道交通接驳方式设施服务不便性指标的感知评价,提出轨道交通接驳设施优化措施。     

An exploration of the relationships between socioeconomics,land use and daily trip chain pattern among low-income residents

Daily trip chain complexity and type choices of low-income residents are examined based on activity travel diary survey data in Nanjing, China. Statistical tests reveal that non-work trip chain complexity is distinctly distinct between low-income residents and non-low-income residents. Low-income residents are inclined to make simple non-work chains. Two types of econometric models, a stereotype logit model and mixed logit model, are then developed to investigate the possible explanatory variables affecting their trip pattern. The number of stops within a chain and chain types are considered as dependent variables, while independent variables include household and personal characteristics as well as land use variables. Results show that once convenient and flexible conditions are supplied, low-income residents are more likely to make multiple activities in a trip chain. Areas with high population and employment densities are associated with complex work trip chains and more non-work activity involvement.     

Examining the relationship between built environment and metro ridership at station-to-station level

Very few studies have examined the impact of built environment on urban rail transit ridership at the station-to-station (origin-destination) level. Moreover, most direct ridership models (DRMs) tend to involve simple a prior assumed linear or log-linear relationship in which the estimated parameters are assumed to hold across the entire data space of the explanatory variables. These models cannot detect any changes in the linear (or non-linear) effects across different values of the features of built environment on urban rail transit ridership, which possibly induces biased results and hides some non-negligible and detailed information. Based on these research gaps, this study develops a time-of-day origin-destination DRM that uses smart card data pertaining to the Nanjing metro system, China. It applies a gradient boosting regression trees model to provide a more refined data mining approach to investigate the non-linear associations between features of the built environment and station-to-station ridership. Data related to the built environment, station type, demographics, and travel impedance including a less used variable – detour, were collected and used in the analysis. The empirical results show that most independent variables are associated with station-to-station ridership in a discontinuous non-linear way, regardless of the time period. The built environment on the origin side has a larger effect on station-to-station ridership than the built environment on the destination side for the morning peak hours, while the opposite holds for the afternoon peak hours and night. The results also indicate that transfer times is more important variables than detour and route distance.     

地铁智能运维平台的环网架构及其性能分析

为实现地铁运维平台的智能化,需要将分散在各个专业系统、各个站点的"数据孤岛"打通,实现数据共享和数据融合。本文针对智能运维平台的应用,提出了3种不同的基于ERPS协议的环网架构,分析并计算其可靠性水平;通过实验室测试,对比每种环网架构的收敛性能指标,给出3种环网架构在地铁建设中的适用场合。