嘉绍大桥主墩承台大体积混凝土裂缝控制

Cracks controlling for mass concrete of main pier pile caps of Jiashao bridge

嘉绍大桥主墩承台结构尺寸大,混凝土内部散热较慢,易导致内表温差较大,同时受封底混凝土及桩基强约束,施工过程中处理不当极易出现裂缝,且承台全部没于水下,混凝土一旦开裂难以修补。针对上述特点,在混凝土温度场及温度应力场仿真计算的基础上,制定了严格的温控标准,通过采取混凝土浇筑温度控制,内部埋设冷却水管并通水冷却、有效保温保湿养护、加强混凝土质量控制等措施,使各承台未出现有害裂缝,达到了预期的控制效果。

According to the case that mass concrete of the main pier pile caps of Jiashao bridge is easy to crack in construction,because of the enormous section size,slow heat dissipation,easily inducing high inner-outer temperature difference,strong constraint of bottom concrete and piles,and it is difficult to repair the cracks on the pile are,because that the pile caps are all underwater,we design the standard of temperature controlling on the basis of simulated result of temperature and thermal stresses distribution of mass concrete.By taking some temperature control measures,such as controlling pouring temperature of concrete,applying recycling cool water,insulated and humidity curing,and controlling the quality of concrete,harmful cracks don＇t appear in the main pier pile caps of Jiashao bridge and anticipated controlling effect is achieved.