关键词: 桥梁工程；大体积混凝土；水化热；冷却水管；热流管单元精细算法

Abstract: 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.

Key words: bridge engineering; mass concrete; the hydration heat; cooling water pipes; fine algorithm of heat flow tube unit