支架法分段现浇预应力变截面连续箱梁的线形控制

市政桥梁的梁体外观线形控制是支架法现浇预应力变截面连续箱梁施工质量的重要控制措施之一。论文根据雄安站西侧干路项目新盖房特大桥支架法现浇预应力变截面连续箱梁线形控制的实际施工经验,重点论述了连续箱梁梁体横、竖桥向线形控制的主要影响因素。通过设计结构预拱度及横竖桥向梁体线形计算、支架预压及监测、施工过程中各参数要点的落实,在一系列计算和监测所得数据指导施工的前提下,使得梁体线形控制取得良好的效果,解决了施工过程中关键技术难题,达到箱梁设计所需要的精确外形曲线的目的,为今后同类工程提供参考。     

高墩大跨预应力混凝土连续梁桥线形控制研究

大跨连续梁工程质量评定的一个重要指标是线形控制准确与否,它不仅影响梁体的外观质量,而且影响梁体的受力状态和运营条件。为确保优质工程,对连续梁施工进行了严格的线形控制,收到良好效果。     

钢箱梁顶推法顶推力计算及梁体线形控制

钢箱梁的顶推施工是一种常用的桥梁施工方法,常用于连续钢箱梁桥施工项目中。以长沙盼盼路上跨京港澳高速公路立交桥为例,采用有限元软件Midas Civil进行顶推模拟,对钢箱梁顶推各工况下顶推力计算及梁体线形控制进行了研究。研究发现,顶推施工过程中,钢箱梁悬臂长度的不断变化,导致梁体应力、竖向变形和支反力时刻发生变化。获得钢箱梁各支点的顶推力及竖向变形值,采取对应措施,以保证顶升时梁体及支架受力安全,使桥梁线形满足设计要求。     

移动模架线形控制在杨家坳特大桥中的应用

移动模架连续梁施工中,影响梁体线形的因素很多,本文结合杨家坳特大桥移动模架的施工实践,分析了移动模架系统施工过程中线形控制的要点。     

预应力混凝土部分斜拉桥的施工控制

针对部分斜拉桥的结构特点,结合工程实例,介绍了部分斜拉桥施工控制的目标、方法以及监控计算的要点;监控时应以主梁的线形控制为主,同时兼顾拉索的索力及梁体的合理应力,确保桥梁施工中的安全和达到设计要求的状态。     

箱梁悬臂灌注线形控制技术

针对箱梁悬臂灌注施工中引起梁体线形变化的诸多因素，通过工程实例分析研究，阐述了施工最优控制方法，提出了使悬灌梁段的合拢精度和成桥后的线形满足设计要求的线形控制与量测的技术措施。     

连续梁线形控制

通过京沪铁路京杭运河特大桥连续梁的施工,总结了连续梁在悬臂施工过程中线形控制方法,分析了影响标高的因素,提出了简单易行的处理方法,从而使施工过程中各节段梁体的标高得到有效的控制。     

大跨度混凝土连续梁桥施工线形控制技术

结合具体工程实例,对大跨度混凝土连续梁桥的施工控制进行了分析,施工过程中对梁体线形进行了实时监测,并将实测值与理论值进行了对比,结果表明该桥施工监控保证了连续梁施工中结构处于稳定状态,最终线形控制结果较好。     

支架法施工大跨度现浇梁预拱度及线形控制技术研究

针对支架法施工大跨度现浇梁预拱度及线形控制施工标准高、难度大的特点,本文结合有关实际工程,主要介绍了支架法施工大跨度现浇梁预拱度及线形控制施工方法和工艺。支架法施工梁体的预拱度值包括弹性变形值和非弹性变形值,通过计算可以得到理论的预拱度值,在施工时通过预压的方法可以得到实测的弹性和非弹性变形值。通过实测和理论的相互验证,精确地得出施工预拱度。通过设置施工预拱度使梁箱的线形得到控制,合理的使用模版施工材料,精确的测量控制可以得到梁箱需要的外形。     

连续梁线形控制

通过温福铁路对务山特大桥连续梁的施工,总结了连续梁在悬臂施工过程中线形控制方法,分析了影响标高的因素,提出了简单易行的处理方法,从而使施工过程中各节段梁体的标高得到有效的控制。     

采场围岩宏观应力壳演化特征

 基于综放采场围岩宏观应力壳的发现及其力学特征的分析,采用现场实测、实验室相似材料模拟试验及计算机数值模拟(FLAC3D)综合方法开展留窄煤柱非对称综放开采采场围岩应力壳壳基、壳体应力演化特征、演化形态及演化参数间的关系分析。研究结果表明,应力壳演化是工作面推进过程中采动高应力在围岩空间的动态平衡过程,其演化形态随工作面推进根据采场结构发生变化,非对称开采条件应力壳演化分为旧壳扩展阶段、新壳形成–壳基上提阶段及新旧壳贯通趋于相对稳定3个阶段,应力壳在覆岩空间中的演化形态近似呈半空间椭球壳,揭示应力壳应力演化及其形态特征。研究为采场围岩控制、巷道布置及其围岩控制、瓦斯抽采、安全高效开采等提供理论依据。     

Application of a self-adaptive Kalman filter approach in alignment control for an extra long span rail transit cable-stayed bridge

Extra long span rail transit bridges are generally slender and sensitive to excitations, and alignment control of the bridges should be conducted during construction. In this paper, the self-adaptive Kalman Filter (SKF) method was applied to the alignment control of the second longest rail transit bridge in the world. Each influential factor of the bridge alignment was firstly introduced. Then, the finite-element analysis and field tests of the bridge were carried out to obtain the influential factors that induced bridge cambers quantitatively. Combining with the cambers, the SKF method was applied to the alignment control of the bridge. Comparisons of the SFK-predicted alignment with the target alignment or the field measured alignment were carried out. Results show the SKF for alignment control of bridges is feasible and reliable.     

移动模架造桥机的设计及在郑州黄河公铁两用桥上的应用

郑州黄河公铁两用桥运用梁模一体的新型移动模架进行铁路箱梁的施工,此种模架充分利用了该桥构件的承载能力,具有工序简单,机械化程度高,受力明确,安全系数大等特点。介绍了该模架的设计原理及设计过程。对设计和建造好的移动模架进行了现场拼装和预压,预压结果满足规范要求。同时还介绍了该桥的具体施工工艺。利用该移动模架成功进行了铁路箱梁的施工。     

Resuspension of coal and coal/municipal sewage sludge combustion generated fine particles for inhalation health effects studies

Airborne particulate matter (PM) is an important environmental issue because of its association with acute respiratory distress in humans, although the specific particle characteristics that cause lung damage have yet to be identified. Particle size, acid aerosols, water-soluble transition metals (e.g. Cu, Fe, V, Ni and Zn), polyaromatic hydrocarbons, and particle composition are the focus of several popular hypotheses addressing respiratory distress. All of the above mentioned characteristics are contained in PM generated from the combustion of both pulverized coal, and biomass, including dried municipal sewage sludge (MSS). In this investigation, we report results from collaborative interdisciplinary research on the inhalation health risks caused by particles emitted from the co-combustion of municipal sewage sludge (MSS) and coal. A solid particle resuspension system was implemented to resuspend ash particles. Mice were exposed to resuspended coal and MSS/coal ash particles. Mice exposed to MSS/coal ash particulate demonstrated significant increases in lung permeability, a marker of the early stages of pathological lung injury, while the mice exposed to coal-only ash did not. These results show that the composition of particles actually inhaled is important in determining lung damage. Zinc was significantly more concentrated in the MSS/coal ash than coal ash particles and the pH of these particles did not differ significantly. Specifically, an MSS/coal mixture, when burned, emits particles that may cause significantly more lung damage than coal alone, and that consequently, the use of MSS as a 'green', CO2-neutral replacement fuel should be carefully considered.     

石太客运专线全自动液压整体内模移动模架关键技术

石太客运专线创造性地采用了全自动液压整体内模,避免了内模分节段拆装,实现了内模就位和脱模自动化,可极大地提高功效;利用移动模架自身结构特点,不需要机械配合,解决了移动模架整体高位提升安装难题;通过移动模架分节模数设计,使其实现墩顶变跨,一套模架可满足不同跨度梁型的需要;利用移动模架现浇连续梁直线段,拓展了模架的使用范围,降低了工程成本.     

上行式移动模架制梁预压试验与线形控制

以某铁路桥梁施工为背景,介绍了DXZ32-900型上行式移动模架制梁预压试验与线形控制技术,同时对试验方法与控制点布置进行了阐述,以期为国内同类工程施工积累经验。     

完全自行式移动模架造桥机在苏通大桥连续梁中应用

介绍了苏通大桥北引桥完全自行式移动模架系统的构造特点及工作原理,分析了移动模架系统施工过程中箱梁底板线形控制要点,针对悬臂端箱梁底板横向应力水平过高的特点,研究裂缝预防措施及工程对策。     

The potential for recycling municipal sewage sludge as a substrate for wetland creation

Municipal sewage sludge (MSS) is proposed as a suitable substrate for wetland creation. Sludge disposal is currently limited to terrestrial conditions due to concern for the transmission of pollutants. Wetland structure and wetland biogeochemical cycles were compared with sludge disposal practices to identify strengths and weaknesses in wetland mechanisms for pollution control. Potential pollution from sludge use is proposed to be mitigated both by wetland function and by the substrate construction method. Because MSS requires specific handling techniques to prevent undesired release into the environment, to protect workers and to be practical for construction, designs responsive to the nature of the construction material were necessary. Three designs were developed, evaluated and compared in terms of aesthetics, educational opportunities, environmental safety, nutrient cycling, waste material utilization, substrate construction requirements and wetland establishment requirements.     

组成和温度对重构钢渣结构及早期水化活性的影响

在转炉钢渣中添加电炉渣和粉煤灰,通过重新加热来模拟炉外高温重构过程,运用岩相、XRD、强度试验及水化热测定等手段,研究了重构钢渣的组成、结构及其胶凝性能.结果显示:随着粉煤灰的增加,重构钢渣中硅酸盐矿物减少,而随着电炉渣的增多;其硅酸盐矿物增多;温度升高,低碱度重构钢渣硅酸盐矿物晶体尺寸增大,高碱度重构钢渣Alite矿增多,且矿物结构完整,游离氧化钙大幅减少.其中GB40-1350重构钢渣样品的3d水化热相比于原钢渣增加1.9倍,GBF15-1350重构钢渣样品替代30%水泥熟料后的水泥净浆28d抗压强度达到纯水泥净浆强度的99.9%.     

Mountain railway alignment optimization integrating layouts of large-scale auxiliary construction projects

Mountain railway alignment design is an important but complex civil engineering problem. To overcome the drastically undulating terrain, long tunnels and high bridges are major structures used along a mountain railway, which poses great challenges for railway design and construction. Unfortunately, despite being studied for many years, the crucial construction factors of complex structures have received slight attention in alignment optimization. In this paper, for the first time, the layout of large-scale auxiliary construction projects (LACPs), including tunnel shafts and access roads, is incorporated into the alignment design process in order to consider construction practicability and economy. Primarily, an alignment–LACPs concurrent optimization model is built. After defining the comprehensive design variables, the alignment–LACPs total construction cost is formulated as the objective function. Besides, the separate constraints for designing the alignment and LACPs are considered. Also, a construction duration computation is proposed for constraining the alignment–LACPs integration. To solve the model, a four-step hybrid solution method is developed. Specifically, the alignment is first generated with a particle swarm optimization (PSO). Afterward, a new divide and conquer approach is devised to search for shaft alternatives along the alignment. Then, a customized Dijkstra algorithm is developed to search for complex access roads. Finally, a novel polynomial mechanism for time-varying acceleration coefficients (TVAC) is designed for PSO to evolve the alignment–LACPs solutions. The above model and methods have been applied to two complex actual mountain railway examples. Their effectiveness is demonstrated through detailed analysis of resulting railway solutions and control experiments with contemporary TVAC-based methods.