高墩三维日照温度场数值模拟及试验研究

Numerical Simulation and Test Analysis of Three-dimensional Solar Temperature Field of Hollow Tall-piers with Rounded Rectangular Cross Section

研究目的:山区高速铁路圆端形空心高墩在日照作用下会存在温差,当截面温差及桥墩高度较大时,就会引起桥墩温度应力及墩顶位移,从而影响高速铁路运行的安全性及舒适性。为获取高墩三维日照温度场及温度变形规律,本文建立高墩三维温度场有限元模型,对高墩日照温度变化开展现场试验及模型验证,以68 m圆端形空心高墩为例,分析高墩径向、竖向温度场,以及高墩在日照作用下的变形和受力特征。研究结论:(1)高墩在日照作用下,径向温度沿壁厚方向变化符合负指数函数T_x=Ae^(-ax)+B变化规律,日照温度影响深度约为0.60 m;(2)桥墩表面竖向温度符合T_z=Ae^(-ax)+kz+B函数变化规律;(3)墩顶最大水平位移发生在18:00左右,因此可取18:00的温度场作为控制荷载,对桥墩结构的变形进行检算;(4)桥墩内、外壁均会受到拉应力的影响,在设计时应同时考虑内、外表面的配筋加强,以保证桥墩的抗裂和安全性;(5)该研究成果可为高速铁路圆端形空心高墩的设计和施工提供参考。

Research purposes： The hollow tall - piers with rounded rectangular cross section of high - speed railways have temperature gradient under the influence of solar radiation. When the temperature gradient and the height of pier exceed the limit, it will influence the safety and comfort of high - speed railways in operation because of the temperature stress and displacement at piers. To determine the changing law of the temperature field and deformations for tall - piers, the three - dimensional finite element model of tall - piers was constructed, and field test of tall - piers temperature field was completed. Taking 68 m tall - piers as an example, the characteristic of the temperature gradients in the longitudinal and transverse bridge directions and the deformation effect under the solar radiation was investigated. Research conclusions：（ 1 ） The temperatures along the direction of wall thickness are in negative exponential Tx =Ae^-ax ＋ B function distribution, the influence depth of temperature is about 0.60 m. （2） The temperatures on the vertical surface of the tall - piers accorded with Tz = Ae^-az ＋ kz ＋ B function distribution. （3） The maximum displacements of a tall - pier at the pier top result from the temperature gradients occur at 18：00. It is hopeful that the findings from this study provide the temperature field of 18：00 as the control loads to calculation the deformation of a bridge. （4） The internal and external surface of tall - piers exist tensile stress, it is hopeful to remind the designer of enhancing the rebar of tall- piers to ensure crack resistance and safety. （5）The research results can provide a reference for design and construction of tall - piers.