为了能够提前获知一期控温阶段混凝土短期内温度变化趋势,及时采取相应温控措施,防止温度裂缝产生,以高拱坝施工期浇筑仓混凝土为研究对象,分析初始温度、通水冷却、绝热温升、环境气温及层面散热等因素对浇筑仓混凝土温度的综合影响,建立适时动态更新初温的高拱坝混凝土一期控温阶段温度变化动态预测模型。同时,考虑不同浇筑仓混凝土的差异性,运用非线性优化法对模型的重要参数进行优化求解,并运用最大绝对误差、平均绝对误差、相对误差等评价指标检验预测模型的精度。最后结合工程实例,以2 d为步长更新初始温度并优化参数,以12 d为龄期,对浇筑仓混凝土温度进行预测,结果表明模型预测值与实测值的最大绝对误差在0.6 ℃以内,平均绝对误差在0.2 ℃以内,相对误差在0.9%以内,预测精度满足施工现场需求。

The aim of this research is to obtain in advance the short-term temperature change trend of concrete in the first stage of temperature control, and take corresponding temperature control measures in time to prevent from temperature cracks. With high arch dam concrete in construction period as the research object, we examined the comprehensive influences of initial temperature, water cooling, adiabatic temperature rise, environmental temperature and layer heat dissipation on the concrete temperature of pouring warehouse, and then established a dynamic prediction model of temperature change in the first stage temperature control stage of high arch dam concrete by timely updating the initial temperature. Furthermore, in view of the difference of concrete in different pouring warehouses, we adopted the nonlinear optimization method to optimize the important parameters of the model, and verified the accuracy of the model using such indicators as maximum absolute error (MAE), average absolute error (AAE) and relative error (RE). With engineering practice as case study, we updated the initial temperature with 2 days as the step and optimized the model parameters, and predicted the concrete temperature of the pouring warehouse with 12 days as the age of concrete. The maximum absolute error (MAE) between predicted value and measured value is within 0.6 ℃, the average absolute error (AAE) within 0.2 ℃, and the relative error (RE) within 0.9%. The prediction accuracy of the model meets the requirements of the construction site.