基于混凝土收缩徐变和基础沉降理论的桥梁扩建方案研究

发布时间：2018-11-12 11:38

【摘要】：随着我国公路交通运输的发展,早期修建的公路通行能力日趋饱和,部分公路已不能满足交通量的增长需求,以前已有很多的桥梁结构已经不能满足现有的通行要求或者超过了原有桥梁的承载能力;在公路改扩建工程中,基于现有的桥梁通行能力和承载能力,为使其满足公路桥梁今后的通行需求,提高公路桥梁的通行能力和服务水平,要么进行改建、要么进行重建或者对原桥进行加固,当然在能满足今后通行和承载能力的基础上是可以继续沿用的,但是当进行桥梁拼宽扩大其通行能力时,新旧桥梁之间的变形和受力协调性问题是桥梁扩建拼宽中的主要问题,在桥梁扩建拼宽中,老桥沉降、收缩、徐变等变形已经基本或大都完成,而新桥刚建会产生较大的沉降、收缩、徐变等变形,导致新老桥之间产生变形差异,从而导致新桥对老桥和老桥对新桥的变形和附加内力的影响,有必要对新桥在产生沉降、收缩、徐变时老桥、新桥中产生的附加内力和变形进行研究,从而为桥梁扩建设计施工提出理论措施建议。本论文以云南小磨二级公路改建为高速公路的龙茵1号大桥改扩建工程中的预应力混凝土T梁桥为依托,使用混凝土收缩徐变计算理论,采用有限元计算软件Midas Civil,深入探讨桥梁在进行扩建以后,由于新旧桥混凝土的收缩徐变以及基础沉降的差异对桥梁上部结构产生的附加影响。本论文开展了以下工作:(1)通过对国内外相关文献资料进行收集分析,总结桥梁扩建过程中常用的设计施工方法及适用条件。(2)研究分析混凝土收缩、徐变的计算方法,总结在不同外界因素作用条件下计算混凝土收缩、徐变的方法、适用条件及存在的问题。(3)结合混凝土收缩、徐变的计算方法,使用有限元软件Midas Civil中的空间梁格法对云南省小磨二级公路改建为高速公路龙茵1号桥梁的扩建工程进行数值模拟计算,工程扩建后,旧桥主梁混凝土收缩、徐变已经大部分完成,新桥混凝土的收缩徐变刚刚开始或还未完成,新旧桥混凝土在收缩徐变上的差异必将产生对桥梁上部结构的附加内力和变形位移的影响,分析因此而产生的附加内力和变形位移的变化规律。(4)由于新桥基础的沉降还未完成,而旧桥的基础沉降已经基本完成,新旧桥的沉降差异必将导致新旧桥主梁之间产生附加内力,分析因此而产生相应的附加内力对新旧桥上部结构的影响以及变化规律。(5)综合分析新旧桥梁由于混凝土的收缩、徐变以及基础沉降的差异产生的附加内力对新旧桥梁本身的内力和变形位移稳定性影响。(6)根据以上模拟计算分析结果和相关桥梁的设计理论、施工方法。总结和提出减小混凝土土收缩徐变差异和基础沉降差异对桥梁结构影响的工程措施,采取科学合理的工程措施。
[Abstract]:With the development of highway transportation in our country, the capacity of the highway built in the early period is becoming more and more saturated, and some of the highways can no longer meet the increasing demand of traffic volume. In the past, many bridge structures have been unable to meet the existing traffic requirements or beyond the original bridge bearing capacity; In the highway reconstruction and expansion project, based on the existing bridge capacity and bearing capacity, in order to meet the future needs of highway bridges, improve the capacity and service level of highway bridges, or rebuild, Either rebuild or reinforce the original bridge. Of course, it can continue to be used on the basis of satisfying the traffic and carrying capacity in the future, but when the bridge is widened to expand its capacity, The problem of deformation and stress coordination between old and new bridges is the main problem in bridge expansion and widening. In the process of bridge expansion and widening, the deformation of old bridges, such as settlement, shrinkage and creep, has been basically or largely completed, but the new bridges will produce large settlement when they are just built. Shrinkage, creep and other deformation, resulting in the new bridge deformation difference between the old bridge and the old bridge on the new bridge deformation and additional internal force, it is necessary to the new bridge in the process of settlement, shrinkage, creep old bridge, The additional internal force and deformation produced in the new bridge are studied, so as to put forward some theoretical measures for the bridge expansion design and construction. This paper is based on the prestressed concrete T-beam bridge in the reconstruction and extension project of Longyin No. 1 Bridge in Yunnan Xiaomo second class highway. The theory of concrete shrinkage and creep calculation is used, and the finite element calculation software Midas Civil, is used. After the expansion of the bridge, the additional effects on the superstructure of the bridge caused by the shrinkage and creep of the new and old bridges and the difference of the foundation settlement are discussed. This paper has carried out the following work: (1) through the collection and analysis of the domestic and foreign related literature, the common design and construction methods and applicable conditions in the process of bridge expansion are summarized. (2) the concrete shrinkage is studied and analyzed. The calculation method of creep, the method of calculating concrete shrinkage and creep under different external factors, the applicable conditions and the existing problems are summarized. (3) combined with the calculation method of concrete shrinkage and creep, The spatial beam method of finite element software Midas Civil is used to simulate the extension of the second grade highway of Xiaomo in Yunnan province into the extension project of Longyin 1 bridge of expressway. After the expansion, the concrete of the main girder of the old bridge shrinks. The creep has been mostly completed, the shrinkage and creep of the new bridge concrete has just begun or not, the difference of the new and old bridge concrete in the shrinkage and creep will have the influence on the additional internal force and the deformation displacement of the superstructure of the bridge. The changes of additional internal force and deformation displacement are analyzed. (4) because the settlement of the new bridge foundation has not been completed, the settlement of the old bridge foundation has been basically completed. The settlement difference between the old and the new bridges will lead to additional internal forces between the main beams of the new and old bridges. The influence of the additional internal force on the superstructure of the new bridge and the old bridge is analyzed. (5) the shrinkage of the new and old bridges due to concrete is comprehensively analyzed. The creep and the additional internal force caused by the difference of foundation settlement affect the stability of internal force and deformation displacement of the new and old bridges. (6) according to the results of simulation calculation above and the design theory and construction method of the bridge concerned. The engineering measures to reduce the difference of shrinkage and creep of concrete soil and the difference of foundation settlement to bridge structure are summarized and put forward, and scientific and reasonable engineering measures are taken.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U445.6

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