南水北调箱涵混凝土裂缝的成因及预防

摘要

Tianjin route of south-water-north project uses pressurized box culvert (15m long in single culvert)of cast-in-place reinforced concrete structure, which is poured by two stages. Cracks are found on culvert side roof con-crete during the early stage of construction. The project engineers presented remedial and preventive measures timely after analyzing the main reasons for cracks, including temperature stress, quality of raw materials, uneven settlement of foundation, upper load, plastic shrinkage, instable template support, vibration of concrete and sub-standard curing etc., which reduced the cracks and obtained the desired effect.%南水北调中线一期工程天津干线采用现浇钢筋混凝土有压输水箱涵的结构形式，单节箱涵长15 m，分两期浇筑。施工前期，箱涵边顶板混凝土出现部分裂缝。分析其原因，主要影响因素有：温度应力、原材料质量、地基不均匀沉降、上部荷载、塑性收缩、模板支撑不稳、混凝土振捣及养护达不到要求等，为此项目工程技术人员认真分析裂缝产生的原因，并及时采取补救与预防措施，有效地减少了裂缝的产生，达到预期效果。