大跨径混合梁斜拉桥临时支墩的设置研究

发布时间：2018-04-01 04:38

本文选题：斜拉桥　切入点：施工监控　出处：《重庆交通大学》2016年硕士论文

【摘要】：为了降低大跨度斜拉桥在大悬臂状态下的施工风险、以及提高结构的整体稳定性,通常采用在边跨设置临时支墩的方法。临时墩一般设置在距离索塔中心约0.6L(L为边跨跨径)附近较为合理。由于地质条件的限制,西藏迫龙沟特大桥(跨径布置为156m+430m+156m的混合梁斜拉桥)边跨未设置辅助墩,边跨与主跨的比例较小,临时支墩设置在距索塔中心27.75m(约0.18L)的地方,不能充分发挥临时支墩的作用,因此,有必要开展该桥施工过程的模拟计算及施工监控。此外,还有必要对临时墩的设置位置以及设置与否进行计算分析,以探讨其他方案的可行性。本文通过计算分析和现场监控等工作,得到以下主要结论:1、本文依托工程为国内首座采用边跨悬浇+中跨悬拼非对称平衡体系的混合梁斜拉桥,采用中跨组合梁超边跨悬浇梁一个节段同步施工的方法,可以有效的控制主塔的不平衡力矩。2、通过对迫龙沟特大桥施工过程进行模拟计算、现场监测和反馈控制,主塔的变形和应力、主梁的变形和应力、斜拉索的内力等主要监测参数的实测值与预测值之间的误差满足要求。3、临时支墩反力的计算值与实测值都反映出了临时支墩未充分发挥其作用,即临时支墩在多数施工工况下没有反力,其为整体结构提供的作用十分有限,且临时支墩的最大反力值为173.3T,远小于其设计使用值(800T),处于安全状态。4、通过对本桥临时支墩设置方案的比较分析得出:当临时支墩设置在3L/4、2L/3、3L/5、L/2时,可以有效减小主塔的水平位移、主塔的根部应力、主梁的成桥位移等,但临时支墩的设置位置对斜拉索成桥索力和主梁应力影响较小;当临时支墩设置在27.75m、L/3、2L/5处时,其在后期大多数施工过程中并无反力,而设置在3L/4处时又无法在前期为整体结构提供作用。5、静力计算结果表明:如果地质条件允许,本桥临时支墩设置在边跨2L/3处更为合理,且不设临时支墩并不会影响全桥结构的静力安全。
[Abstract]:In order to reduce the construction risk of long-span cable-stayed bridge under the condition of large cantilever, and to improve the overall stability of the structure, The method of setting temporary piers at side spans is usually adopted. The temporary piers are generally located near the center of the cable tower about 0.6L(L as the side span. There are no auxiliary piers on the side span of the Julonggou extra large Bridge (a cable-stayed bridge with a hybrid beam with a span of 156m 430m 156m), and the ratio of the side span to the main span is small, and the temporary pier is located 27.75m (about 0.18L) from the center of the cable tower. Therefore, it is necessary to carry out the simulation calculation and construction monitoring during the construction of the bridge. In addition, it is necessary to calculate and analyze the location of temporary pier and whether it is installed or not. In order to explore the feasibility of other schemes, this paper obtains the following main conclusions: 1 through calculation, analysis and field monitoring. This paper relies on the project to build the first hybrid girder cable-stayed bridge in China, which uses the asymmetric balance system of side span suspension casting and middle span suspension assembly. By adopting the method of synchronous construction of a section of overside-span cantilever cast-in-situ beam with mid-span composite beam, the unbalance moment of main tower can be effectively controlled. Through the simulation calculation, field monitoring and feedback control of the construction process of the oversized bridge of forced Longgou, The deformation and stress of the main tower, the deformation and stress of the main beam, The error between the measured and predicted values of the main monitoring parameters, such as the internal force of the stay cable, meets the requirement of .3.The calculation value and the measured value of the reaction force of the temporary pier all reflect that the temporary pier has not fully played its role. That is, the temporary pier has no reaction force under most construction conditions, and its function for the whole structure is very limited. The maximum reaction force of temporary pier is 173.3T, which is much smaller than its designed use value of 800Tu, and is in a safe state. By comparing and analyzing the scheme of temporary pier arrangement, it is concluded that when the temporary pier is set at 3L / 4L / 3L / 3L / 5L / 2, the horizontal displacement of the main tower can be reduced effectively. The stress at the root of the main tower and the bridge displacement of the main girder have little effect on the cable force and the stress of the main beam of the cable-stayed cable-stayed bridge, and when the temporary pier is set at 27.75mL / 32L / 5, there is no reaction force in most of the later construction processes. The static calculation results show that, if geological conditions permit, it is more reasonable for the temporary pier of the bridge to be located at the side span 2L/3. And the static safety of the whole bridge structure will not be affected by the temporary pier.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U445.4;U448.27

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