高速铁路大跨度节段拼装梁桥施工过程中的力学行为分析

发布时间：2018-10-11 06:58

【摘要】：高速铁路中的桥梁主要采用简支箱梁结构,对于40m以上大跨度简支箱梁桥,目前采用节段预制拼装法施工,由于施工工艺的复杂性和对设备要求的特殊性,该技术在我国起步较晚,而且发展十分缓慢。如今我国高铁正处于黄金发展时期,对该工艺相关技术进行研究和总结具有很重要的现实意义。本文以西成客运专线汉江特大桥为背景,结合国内外最新研究成果,对施工过程中的关键技术进行力学仿真分析,并提出相应的改进措施。节段预制拼装施工过程中拼装线形控制非常重要,直接影响梁体的成桥线形。文中对施工过程中影响梁体线形的主要因素进行分析,将线形控制分为三个阶段:节段预制阶段、拼装阶段以及预应力张拉阶段。通过进行三阶段线形控制,以保证梁体拼装线形满足设计要求。移动支架造桥机在整个拼装施工过程中是主要承重结构,其受力和变形性能直接影响梁体的施工质量以及拼装线形。在施工之前对造桥机进行预压试验,通过实时测量各控制截面挠曲变形和主要受力杆件的应力,分析在施工过程中其强度与刚度是否满足最大施工荷载的要求。通过在预应力张拉完毕后对桥面线形进行测量,得出线形控制效果良好,满足要求。预应力张拉之前,整个梁体重量通过吊杆多点支撑在移动支架造桥机上。随着预应力的张拉,梁体开始逐渐承受自重,同时吊杆力减小,造桥机发生反弹。由于梁体与造桥机刚度不协调,为了防止梁体在自重、预应力和吊杆力作用下上缘产生过大拉应力造成梁顶接缝处开裂,在张拉过程中要对梁体进行受力分析,以确定是否需要在张拉过程中对悬吊系统进行卸载,以减少造桥机对梁体的上托力。最后利用MIDAS Civil软件对64m节段预制拼装梁的收缩徐变效应进行分析。分析对比节段拼装和整孔预制梁后期徐变效应,分析表明节段拼装梁前期收缩徐变效应较整体预制梁的小,而其后期变形较大;其次还对影响混凝土时效变形的因素分别进行参数敏感性分析,随着湿接缝混凝土养护龄期的增大或二期铺装过早,结构前期徐变变形较小,后期相对较大。此外环境湿度对于结构收缩徐变也是一个敏感的控制因素。
[Abstract]:The bridge in high-speed railway mainly adopts simply supported box girder structure. For the large span simple box girder bridge above 40 m, the section precast assembling method is used at present, because of the complexity of construction technology and the particularity of equipment requirement. This technology starts late in our country, and the development is very slow. At present, high-speed rail is in the golden development period in China. It is of great practical significance to study and summarize the related technology of this process. Based on the latest research results at home and abroad, this paper analyzes the key technologies in the construction process and puts forward the corresponding improvement measures against the background of the Hanjiang Bridge in the west of Chengcheng passenger dedicated Line. The control of assembly alignment is very important in the construction of segmental prefabricated assembly, which directly affects the bridge alignment of beam body. In this paper, the main factors affecting the beam alignment in the construction process are analyzed, and the linear control is divided into three stages: segment prefabrication stage, assembling stage and prestressing tensioning stage. The three-stage alignment control is carried out to ensure that the beam assembly meets the design requirements. The moving support bridge construction machine is the main load-bearing structure in the whole assembly construction process, and its stress and deformation performance directly affect the construction quality of the beam body and the assembly line shape. The preloading test was carried out on the bridge builder before construction. The flexural deformation of each control section and the stress of the main members were measured in real time, and the strength and stiffness of the bridge construction were analyzed whether the strength and stiffness of the bridge could meet the requirements of the maximum construction load. By measuring the line shape of the bridge deck after the prestressing tension is finished, it is concluded that the linear control effect is good and meets the requirements. Before the prestressing tension, the whole beam weight is supported on the mobile support bridge machine through the suspension pole. With the tensioning of prestress, the beam begins to bear the weight gradually, and the suspender force decreases and the bridge maker rebounds. Because the stiffness of beam body and bridge machine is not in harmony, in order to prevent the excessive tensile stress in the upper edge of beam body under the action of self-weight, prestress and suspender force, the crack at the top joint of the beam should be analyzed in the process of tensioning. To determine whether it is necessary to unload the suspension system during tensioning, so as to reduce the support force of the bridge maker to the beam. Finally, the shrinkage and creep effect of 64m precast assembly beam is analyzed by MIDAS Civil software. The results show that the early shrinkage and creep effect of segmental prefabricated beam is smaller than that of the whole prefabricated beam, but the later deformation is larger. Secondly, the parameter sensitivity analysis of the factors affecting aging deformation of concrete is carried out. With the increase of curing age of wet jointed concrete or the premature paving of the second stage, the creep deformation in the early stage of the structure is small and the later stage is relatively large. In addition, environmental humidity is also a sensitive control factor for structural shrinkage and creep.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.4

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