考虑水化度对热学参数影响的早期混凝土温度场分析

Thermal field analysis of early-age concrete considering effects of degree of hydration on thermal conductivity

为了更加准确地模拟早期混凝土的温度场,通过试验研究了早期混凝土温度的变化规律,同时基于ABAQUS二次开发平台,考虑早期混凝土热学参数(导热系数和比热容)随水化度的变化规律,开发了温度场子程序UMATHT和用于模拟温度场第3类边界条件的FILM子程序.在此基础上,采用不同的温度场计算模型对试验进行数值模拟,通过实验结果与数值模拟结果的对比得出:考虑比热容及导热系数随水化度的变化过程,数值模拟结果与实测值基本一致,最大误差控制在1.5%以内,达到温度峰值的时间误差控制在0.5 h以内;当不考虑这2个参数随水化过程的变化,数值模拟与实测值存在较大误差,峰值温度误差均在4.6℃以上,达到峰值温度的时间均延长5 h以上.因此在对早期混凝土的温度场分析时有必要考虑导热系数和比热容随水化度的变化.

In order to more accurately simulate the temperature field of early-age concrete, the temper- ature changing rules of early-age concrete are studied through the laboratory experiment. Based on the ABAQUS secondary development platform, considering early-age concrete thermal parameters （ther- mal conductivity and specific heat） changing along with the degree of hydration, the thermal field sub- routine UMATHT and user subroutine FILM which is used to simulate the third boundary condition of thermal field are developed. On this basis, different temperature field computational models are used to simulate the test. By comparing the experimental results with the numerical simulation results, it is found that, considering the specific heat and thermal conductivity varying with the degree of hydration process, the numerical simulation results and the measured values are basically consistent, the maxi- mum error of the peak temperature is controlled within 1.5 % and the time error to reach peak tempera- ture is controlled within 0.5 h. Without considering the two parameters varying with the hydration process, there is a big difference between numerical simulation and the measured values, peak temper- ature error is up to more than 4.6 ℃, and the time delay reaching the peak temperature is more than 5 h. Therefore, it is necessary to consider the thermal conductivity and specific heat varying with the de- gree of hydration when the temperature field of early-age concrete is analyzed.