桥梁施工浮式平台的静动力分析

发布时间：2018-06-25 00:30

本文选题：浮式平台 + 水弹簧　；参考：《湘潭大学》2014年硕士论文

【摘要】：在深水中建设桥梁时，一般采用大直径钻孔灌注桩作为桥梁的墩基础，在施工时，容易受到水深、洪水、通航等的限制，因此就必须设置临时的施工平台来排除施工干扰以及解决精确定位等问题。本文针对现有的桥梁深水桩基础施工平台，在大型起吊设备进场困难、水流速度较小等条件下，，采用固定式施工平台或采用船舶等组拼成的浮式施工平台，已无法满足施工需求的前提下，对采用小型浮箱组拼成的浮式施工平台进行研究。首先，回顾了国内外对深水桩基础施工平台的研究现状，通过对比固定式施工平台和浮式施工平台的优缺点，指出了对浮式施工平台进行深入研究的必要性。然后，以有限元理论为基础，建立整体浮式平台的三维梁板分析模型，并将零吃水假定和水弹簧的概念引入分析当中，以单箱在自重及偏载情况下采用理论计算、均布水弹簧刚度及不均匀水弹簧刚度的吃水深度进行对比，分析结果表明采用不均匀水弹簧刚度进行计算可获得较为精确的结果。第三，采用浮箱间刚接、铰接及半刚接分别计算浮式平台在各工况下的位移及应力分布。结果表明，采用刚接、铰接及半刚接时，其位移差别不大，其应力则相差较大。这主要是由于上部工作平台的纵梁将浮式平台连为整体，使得浮式平台纵向刚度较大。在各静态荷载工况下，浮式平台的各项指标均符合规范要求，浮式平台整体性能良好。最后，对浮式平台在移动及冲击荷载作用下的动力响应进行分析。由于浮式平台整体刚度较大及龙门吊移动速度较小，浮式平台在移动荷载作用下考虑与不考虑附加水质量和水动力阻尼时，其动力响应并不明显；而在冲击荷载作用下，浮式平台考虑与不考虑附加水质量和水动力阻尼时则有较大区别。不考虑时，浮式平台的动力响应出现明显的周期性增强现象，且其峰值也随着体系振动逐渐衰减；在考虑时，浮式平台的动力响应也有较微弱的周期性增强现象。
[Abstract]:In the construction of bridges in deep water, large diameter bored cast-in-place piles are generally used as the piers foundation of bridges. In construction, they are liable to be restricted by water depth, flood, navigation, etc. Therefore, it is necessary to set up temporary construction platform to eliminate construction interference and solve the problem of accurate positioning. This paper aims at the existing bridge deep water pile foundation construction platform, under the condition that the large lifting equipment is difficult to enter the field and the flow velocity is small, the fixed construction platform or the floating construction platform composed of ships and so on are adopted. On the premise that the construction demand can not be satisfied, the floating construction platform composed of small floating box group is studied. Firstly, this paper reviews the research status of deep water pile foundation construction platform at home and abroad, and points out the necessity of further research on floating construction platform by comparing the advantages and disadvantages of fixed construction platform and floating construction platform. Then, based on the finite element theory, the three-dimensional beam-plate analysis model of the whole floating platform is established, and the zero-draught assumption and the concept of water spring are introduced into the analysis. The stiffness of uniform spring is compared with that of non-uniform spring. The results show that the stiffness of non-uniform spring can be calculated accurately. Thirdly, the displacement and stress distribution of floating platform under different working conditions are calculated by rigid connection, hinge connection and semi-rigid connection. The results show that the displacement and stress of rigid, hinged and semi-rigid joints are not different. This is mainly because the longitudinal beam of the upper platform connects the floating platform as a whole, which makes the longitudinal stiffness of the floating platform larger. Under various static load conditions, all the indexes of the floating platform meet the requirements of the specification, and the overall performance of the floating platform is good. Finally, the dynamic response of floating platform under moving and impact loads is analyzed. Because the overall stiffness of the floating platform is large and the moving speed of the gantry crane is small, the dynamic response of the floating platform is not obvious when the additional water mass and hydrodynamic damping are considered and not considered under the moving load, but under the impact load, the dynamic response of the floating platform is not obvious. The floating platform is different from that without additional water mass and hydrodynamic damping. When the dynamic response of the floating platform is not considered, the dynamic response of the floating platform appears obvious periodic enhancement phenomenon, and its peak value gradually attenuates with the system vibration, and the dynamic response of the floating platform also has the weak periodic enhancement phenomenon when considering the dynamic response of the floating platform.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U445.3

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