盾构隧道穿越桥梁桩基群的桩基托换技术研究

为探析盾构隧道穿越桥梁桩基群中桩基托换过程的受力转换机理及盾构隧道掘进对群桩基础结构的影响,文章以深圳地铁10号线盾构隧道穿越广深高速桥梁桩基群为工程背景,采用FLAC~(3D)开展桩基托换与地铁隧道施工的数值模拟。研究结果表明:桩基托换后,桥梁荷载体系从桥面板→桩基→地基土转换为桥面板→既有桩基+托换桩→地基土,被托换桩的上覆荷载能够有效地转移到新建托换桩上;在桩基托换与盾构掘进过程中所产生的沉降变形能够提高桩端阻力与桩侧摩阻力,使得桩基结构的最大主应力有所降低;桥梁桩基沉降量以盾构隧道推进过程中由地层损失和掘进扰动产生的沉降变形为主,桩基托换所产生的沉降量占总沉降量的20%~30%;桩基沉降变形、侧向位移与主应力降低效应均主要表现在托换桩上,非托换桩变化不大;盾构隧道管片衬砌结构变形主要产生在桩基托换区域附近,且以沉降变形为主,水平位移较小。     

地铁隧道穿越护城河桥桩基托换施工技术

介绍北京地铁五号线隧道穿越护城河桥桩基托换施工技术措施。施工中采用了全断面帷幕注浆和植筋等工艺。     

大跨径桥梁体外预应力加固工程施工方法

对桥梁施加体外预应力的加固方法,从结构上可改善桥梁的受力性能,并恢复和提高桥梁的强度、刚度和耐久性,能防止和控制桥体的裂缝生成,避免或阻止钢筋受蚀,使桥体线形达到设计要求。文章结合洛维大桥加固工程实例,介绍了大跨径桥梁体外预应力加固施工方法,并阐述了该工程加固方法的优越性。     

上海体育场站换乘段托换桩、梁设计新思路

明珠线二期上海体育场站穿越毫无预留措施的地铁1号线车站，托换桩、托换梁的安全有效是保证这一目标实施的重要环节，从工程需要出发，对托换桩、托换梁的方案比选、结构计算、构造研究、施工控制进行了创造性探讨，其探索过程为正在进行和将要进行的类似项目提供了借鉴。     

桥盖梁体外预应力加固施工技术

装配式桥梁的盖梁在墩顶的竖向裂缝是该类型桥的常见病害。以某桥盖梁体外预应力加固工程为例,对该桥的病害情况及其原因进行分析,采用体外预应力束对盖梁进行加固处理。探讨了盖梁体外预应力钢束加固技术,介绍了使用的材料、施工流程,研究了混凝土表面凿毛、植筋及张拉预应力等相关工艺的关键问题,以供相关技术人员参考。     

津滨轻轨基础托换工程关键技术创新

天津滨海新区中央大道新港四号路地道需穿越运营中的津滨轻轨高架桥。该节点采用基础主动托换方式对津滨轻轨三跨连续高架桥的一个制动墩和一个连接墩进行整体托换,采用两跨连续格构大梁配三排九根桩基同时托换两个轻轨桥墩,构成复杂的超静定空间结构体系。归纳总结了该工程总体设计、结构计算、施工工艺和施工监控中的多项创新技术。     

某箱型拱桥病害调查及加固方案设计

文章以云南某箱型拱桥为工程实例,分析了该桥受重交通荷载影响而出现的裂缝、板块断裂、铺装层推移及桥梁拱轴线下挠等病害类型及其成因,提出了更换原上部结构T型梁、封闭环套加固技术等分布加固维修方案,并对加固后的桥梁结构进行力学验算,结果表明:加固后主拱圈各控制截面安全富裕量显著增加,桥梁承载能力得到大幅度提高。     

南友高速公路龙州左江大桥维修加固实践分析

文章结合龙州左江大桥维修加固工程实例,介绍了该桥总体维修加固方案,分别阐述了支座更换与粘贴钢板两种维修加固施工工艺要点,为类似桥梁维修加固提供参考。     

预应力混凝土空心板梁桥检测评定与加固策略研究

杭千高速公路大塘垄高架桥预应力混凝土空心板梁桥在运营过程中,发现了开裂等病害,预应力空心板梁桥的开裂问题在我国高速公路桥梁中是十分普遍的。本文以大塘垄高架桥20m跨预应力混凝土空心板梁桥的检测评定与加固实践论述该类桥梁的病害原因,病害对结构的影响,以及对病害桥梁的加固处理方法。本文研究内容可为同类桥梁的检测与加固提供借鉴。     

多孔双曲拱桥加固加宽典型案例研究

早期修建的双曲拱桥运行多年,大部分已不能满足道路交通的要求,需要拆除重建或加宽加固。文章结合福建省将乐县三华大桥桥梁实际情况,提出了一系列加固加宽措施及交通工程保障措施,提高了桥梁的结构安全和道路通行能力。     

拱形跨线天桥设计

介绍了上海某高架车站跨线天桥桥型可行性比选、总体结构布局设计、静力分析及稳定性分析的过程,并概述了天桥整体吊装安装工艺,提供了一些城市轨道交通配套天桥设计的思路,可供同类工程参考。     

城市轨道交通企业多元化发展对比研究

城市轨道交通投资周期长、成本高、收益见效慢,许多轨道交通企业负债累累,但随着城市轨道交通在我国的高速发展,越来越多的轨道交通企业开启多元化经营进而实现多元化发展。本文列举了四个我国典型大都市的轨道交通多元化发展情况,结合政府颁布的土地政策,可以看出轨道交通多元化发展的重要性,以及政府将土地交由轨道交通企业自行开发、使用,政府在其中主要充当监管者的角色。这样有助于实现其多元化经营,进而带动多元化发展与城市可持续发展。     

Choosing the wrong technology: Or how to spend billions and reduce transit use

In spite of a broad consensus among transportation analysts that bus rapid transit, whether operating on exclusive rights-of-way or on uncongested high occupancy vehicle lanes or general purpose limited access facilities, provides higher performance and has significantly lower costs per passenger trip than rail transit in medium and low density cities, nearly all Sunbelt cities are building or planning heavy or light rail systems. This paper reviews previous studies of the cost-effectiveness of heavy and light rail transit with bus-rapid transit and the growing experience with busways and transitways and concludes, once again, that some form of bus rapid transit would be a far more effective way of providing improved transit in these cities than heavy or light rail transit. Not only would bus rapid transit be substantially cheaper, but it would provide a higher quality of service than light or heavy rail transit for virtually all users. Finally, the paper speculates on the reasons for the continued, “blind” commitment to rail transit by policymakers in Sunbelt cities and on the refusal of policymakers in all but a few of these cities to even consider bus rapid transit.     

关于城市轨道交通工程水文地质勘察工作的探讨

结合轨道交通岩土工程勘察的特点,对当前水文地质勘察的外业与室内试验工作进行了分析与探讨,并对轨道交通工程中水文地质条件分析与评价进行了阐述,阐明了该项工作在轨道交通工程中的重要性与必要性,以供同行参考.     

Evaluating security of rail transit systems: A metric system approach

Crime and fear of crime is a major problem plaguing U.S. transit systems, particularly those serving large urban areas. This paper presents a normative framework for assessing rail transit security following a system-wide metric approach. The security metric can also be used to assess the marginal improvement in security as a result of improving or adopting alternative policing and monitoring strategies. The model consists of five tasks: surveying rail transit security systems, developing a rail transit security metric, assigning efficiency ratings to rail security functions, developing a composite index for the efficiency of the overall security system, and applying a probability matrix to temper the results. Efficiency ratings can be translated into probability of occurrence figures that can be used in a decision tree context to improve rail transit security.     

Modeling a rail transit alignment considering different objectives

An optimization model for station locations for an on-ground rail transit line is developed using different objective functions of demand and cost as both influence the planning of a rail transit alignment. A microscopic analysis is performed to develop a rail transit alignment in a given corridor considering a many-to-one travel demand pattern. A variable demand case is considered as it replicates a realistic scenario for planning a rail transit line. A Genetic Algorithm (GA) based on a Geographical Information System (GIS) database is developed to optimize the station locations for a rail transit alignment. The first objective is to minimize the total system cost per person, which is a function of user cost, operator cost, and location cost. The second objective is to maximize the ridership or the service coverage of the rail transit alignment. The user cost per person is minimized separately as the third objective because the user cost is one of the most important decision-making factors for planning a transit system from the users’ perspective. A transit planner can make an informed decision between various alternatives based on the results obtained using different objective functions. The model is applied in a case study in the Washington, DC area. The optimal locations and sequence of stations obtained using the three objective functions are presented and a comparative study between the results obtained is shown in the paper. In future works we will develop a combinatorial optimization problem using the aforementioned objectives for the rail transit alignment planning and design problem.     

轨道交通双腹板双线薄壁槽形梁设计优化分析

槽形梁是一种梁、板组合的下承式结构形式，具有建筑高度低、断面空间利用率高、外形美观等特点，特别适用于城市轨道交通跨线、跨河处净空受限制的工程。本文对城市轨道交通35m双线简支槽型梁的关键设计参数进行了对比分析研究，可为双线简支槽型梁的设计提供参考。     

城市轨道交通运营突发事件应急处置体系的思考

结合上海轨道交通网络化运营生产组织工作实际,针对轨道交通生产经营过程中的风险源,对其运营突发事件的应急处置工作进行分析和研究,从风险源分析、能力评估、组织架构及体系建设等方面着手,提出能够适应城市轨道交通网络化运营需求应急处置体系的一些设想。     

The federal rail transit policy: Rhetoric or reality?

Almost two years ago the U.S. Department of Transportation issued a formal statement of policy on rail transit. The aim of the policy was to articulate more clearly some of the basic principles and philosophy which would guide Federal participation in urban rail transit investment. The paper examines the principal tenets of the policy and assesses its influence on local rail transit development.     

模块化产业链视角的城市轨道交通设计行业知识整合体系探讨

首先从模块化产业链的视角分析了城市轨道交通设计行业总线模块化结构；描述了知识结构和知识分工的方式，进而对城市轨道交通设计行业的知识整合模式进行了剖析；探讨了知识整合模式运作的知识竞争、知识创新、组织结构等因素；形成了较为全面的城市轨道交通设计行业知识整合思路。