公路路桥过渡段刚性楔形搭板应用研究及参数优化

发布时间：2018-04-24 17:47

  本文选题：公路路桥过渡段 + 刚性楔形搭板　； 参考：《北京交通大学》2017年硕士论文

【摘要】：由于路基和桥台的不均匀沉降和刚度差异,在路桥过渡段常发生桥头跳车现象,将对舒适性、安全性、结构和车辆的耐久性造成不利影响。设置搭板是一种比较常见的改善方法,而普通桥头搭板易出现搭板折断和二次跳车等多种病害,刚性楔形搭板则能体现搭板的优势且能克服以上的病害。本文以刚性楔形搭板为研究对象,采用了数值模拟方法,建立了车辆-过渡段三维耦合动力学模型,选取了车体竖向振动加速度、动荷载系数、前后车轮竖向位移差和搭板两端错台高度作为评价指标,分析了刚性楔形搭板不同上表面坡度、最大厚度、弹性模量和长度取值对车辆行驶平顺性的影响,研究了以不同车速经过过渡段时平顺性的差异,探究了车速较快时刚性楔形搭板对桥头跳车的改善作用,构造不同路面随机不平顺,提出了随机不平顺条件下搭板对车辆行驶平顺性的改善效果。通过以上内容研究,得到了如下结论:(1)设置楔形搭板可以明显地减小车体竖向加速度;楔形搭板上表面坡度、长度的增加,可以减小搭板远离桥台一端的错台高度;楔形搭板弹性模量和最大厚度的增加,可以减小搭板靠近桥台一端的错台高度;楔形搭板最大厚度的增加,有利于减小前后轮竖向最大位移差和车轮最大动荷载系数;同时搭板长度不宜小于车辆长度。在本文工程条件下,建议选择上表面坡度10～20‰;搭板长度不小于7m;最大厚度0.30～0.40m;弹性模量选取C80混凝土。(2)在过渡段条件一定的情况下,车速越快,车辆的动力响应增长得越快;速度在10m/s(36km/h)以内时,速度对车辆动力响应的影响不大,而速度由20m/s(72km/h)增加到30m/s(108km/h)时,车辆的最大竖向加速度增加了 104.6%,前轮最大动荷载系数增加了 55.9%,后轮最大动荷载系数增加了 57.3%,前后轮最大竖向位移差增加了 25%。因此当各种措施无法明显减小车辆动力学响应时建议限制车速在10m/s(36km/h)以内,;随着速度的增大,搭板对加速度的改善效果减弱。(3)在假设设置搭板不能缓解路面不平顺程度的条件下,传统搭板和刚性楔形搭板在改善随机不平顺影响下车辆的动力响应的效果非常微弱,搭板的设置对前后轮竖向位移差没有任何改善作用。
[Abstract]:Due to the uneven settlement and stiffness difference between subgrade and abutment, bridge-head jump often occurs in the transition section of road and bridge, which will adversely affect the comfort, safety, structure and durability of the vehicle. Setting slabs is a common improvement method, but common bridgehead abutments are prone to many kinds of diseases, such as lap slab breakage and secondary jump. Rigid wedge-shaped slab can reflect the advantages of lapping slab and overcome the above diseases. In this paper, a three-dimensional coupling dynamic model of vehicle-transition section is established by using the numerical simulation method, and the vertical vibration acceleration and dynamic load coefficient of the vehicle body are selected. The vertical displacement difference of the front and rear wheels and the height of the staggered platform at both ends of the slabs are used as the evaluation indexes. The effects of different upper surface slope, maximum thickness, modulus of elasticity and length on the ride comfort of the rigid wedge-shaped slab are analyzed. This paper studies the difference of ride comfort when passing through the transition section with different speed, probes into the improvement effect of rigid wedge-shaped slab on bridgehead jumping when the speed is fast, and constructs different road surface random irregularity. The improvement effect of slabs on vehicle ride comfort under the condition of random irregularity is put forward. Through the above research, the following conclusions are obtained: (1) the vertical acceleration of the car body can be obviously reduced by setting the wedge-shaped lap plate, and the height of the staggered platform at the end of the bridge abutment can be reduced with the increase of the slope and length of the upper surface of the wedge lap plate; The increase of elastic modulus and maximum thickness of wedge-shaped slab can reduce the height of staggered platform near one end of abutment, and the increase of maximum thickness of wedge-shaped slab is helpful to reduce the maximum vertical displacement difference of front and rear wheel and the maximum dynamic load coefficient of wheel. At the same time, the length of the slab should not be less than the length of the vehicle Under the engineering condition of this paper, it is suggested to choose the upper surface slope of 10 ~ 20 鈥，

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