大跨暗涵衬砌混凝土温度数值分析与裂缝控制

Numerical analysis of concrete temperature and crack controlling of large-span culvert lining

以南水北调中线石京段古运河枢纽工程暗涵段为工程背景,采用理论分析和数值计算,提出了南水北调暗涵衬砌结构施工过程中钢筋混凝土内部温降的控制标准,即按最不利部位考虑,30 d内混凝土内部温降不应超过26.7℃,为选取合理的温控措施提供了依据。以衬砌内部温度场数值分析为理论依据,结合下穿段暗涵的地形条件、结构特点,并考虑工程气候特点,优化混凝土配比、降低水泥用量、掺入适量粉煤灰以及采用遮阳棚和地垄等工程措施,有效控制了混凝土结构的内部温度变化,成功解决了大体积混凝土施工温度裂缝问题,保证了结构工程的施工质量。理论计算与现场量测相结合,结果表明,实测值与计算值规律基本一致,说明计算模型和计算参数选取的合理性和计算结果的正确性,可为后续类似工程提供参考。

Based on the geological conditions of culvert of the South to North Water Transfer Project, control criterion of concrete temperature drop is put forward during culvert construction using theoretical analysis and numerical calculation. Considering the worst position, internal temperature of concrete must be controlled below 26.7℃, which can bring good predict effects on selecting reasonable temperature drop measures. According to numerical analysis results of lining temperature field, considering terrain condition, structural characteristics and climate, some engineering measures such as optimizing concrete mixing ratio, reducing cement content, adding proper fly ash and establishing shading shed and furrow, are taken during construction. Internal temperature of concrete is controlled effectively; concrete cracking caused by temperature changes is solved successfully; and construction quality is assured. The difference between measuring data in-situ and calculating data is very small; so it is shown that the calculated model is correct and the parameters are reasonable. The results can act as reference for the design and construction of similar projects.