含有冷管的混凝土承台瞬态温度场及精细化分析模型研究

Transient Temperature Field and Fine Analysis Model of Concrete Cap Containing Cold Pipe

设置冷却水管是降低大体积混凝土承台水化热的常用方法,计算分析中一般采用等效算法,忽略了冷却水的沿程升温作用,一定程度上夸大了冷却水管的降温效果。为精确分析冷却水管沿程温度变化对承台混凝土水化热的降温作用,提出了一种考虑冷管温度沿程变化的混凝土承台精细化分析模型。利用ANSYS中APDL程序语言,采用Gnielinski公式确定对流系数,建立了参数化模型,实现了矩形承台的自动化建模,分析了不同算法、水流流速、水管长度与水管材料对混凝土瞬态温度场的影响,研究了多因素影响下混凝土温度变化的规律,探讨了水管直径与水管间距的最优组合。研究表明:考虑冷管沿程温度变化后能更精确的模拟承台混凝土温度场分布,合理的流速、管长及管材可以取得更为理想的降温效果;此外,在水管材料用量不变的情况下,管径、管间距越小,混凝土最高温度越低。

Setting cooling water pipe is a common method to reduce hydration heat of mass concrete cap.In the calculation and analysis,the equivalent algorithm is generally adopted,ignoring the heating effect of cooling water along the way and exaggerating the cooling effect of cooling water pipe to some extent.In order to accurately analyze the cooling effect of temperature variation along cooling water pipe on the hydration heat of concrete caps,a fine analysis model of concrete caps was proposed,which took the temperature variation of cold pipe along the process into account.Making use of ANSYS APDL programming language,the convection coefficient was determined by Gnielinski formula.The parametric model was established,and the automatic modeling of rectangular pile cap was realized.The effects of different algorithms,flow velocity,pipe length and pipe material on the transient temperature field of concrete were analyzed,the rule of concrete temperature change under the influence of many factors was studied and the optimal combination of pipe diameter and pipe spacing was discussed.The research indicates that the temperature field distribution of bearing platform concrete can be simulated more accurately after considering the temperature change along the cold pipe,and the reasonable flow rate,pipe length and pipe material can achieve more ideal cooling effect.In addition,the smaller the pipe diameter and pipe spacing are,the lower the maximum temperature of concrete is under the condition that the amount of water pipe material remains unchanged.