钢板桩围堰法承台大体积混凝土冬期施工技术
摘要：为提高承台大体积混凝土施工效率，改善钢板桩围堰复杂内支撑对承台施工影响，对龙潭长江大桥深大基坑结构支护体系进行了优化，采用精轧螺纹钢外拉体系替代了传统的型钢、钢管内支撑体系，并采用Midas进行仿真计算，计算结果表明各工况验算均满足施工要求。为加强冬期施工大体积混凝土表面保温效果，减小承台大体积混凝土开裂风险，龙潭长江大桥选用合理的保温材料对混凝土表面进行了保温养护，提高了混凝土表面温度，从而减小了内表温差。通过在混凝土内部埋设温度传感器，可实时监测混凝土内部温度变化情况，监测结果表明混凝土内表温差满足施工方案及规范要求，达到了控制大体积混凝土温度裂缝的目的。
关键词：桥梁工程大体积混凝土钢板桩围堰有限元分析冬期施工温度裂缝
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Winter Construction Technology of Large Volume Concrete of Steel Sheet Pile Cofferdam Cap
Abstract: In order to improve the construction efficiency of large-volume concrete caps and improve the influence of the complex internal support of the steel sheet pile cofferdam on the construction of the caps, the Longtan Yangtze River Bridge has optimized the support system of the deep and large foundation excavation structure and replaced the traditional external tension system with fine-rolled rebar. The internal support system of steel sections and steel pipes is simulated by Midas. The calculation results show that the check calculations of all working conditions meet the construction requirements. In order to strengthen the thermal insulation effect of the mass concrete surface in winter construction and reduce the risk of cracking of the mass concrete on the caps, Longtan Yangtze River Bridge selected reasonable thermal insulation materials to maintain the concrete surface, increase the concrete surface temperature, and reduce the internal surface temperature difference. By embedding a temperature sensor inside the concrete, the temperature change inside the concrete can be monitored in real time. The monitoring results show that the temperature difference between the inner surface of the concrete meets the requirements of the construction plan and specifications, and the purpose of controlling the temperature cracks of the mass concrete is achieved.
Keywords: bridges; mass concrete; steel sheet pile cofferdam; finite element analysis; winter construction; temperature cracks
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