宜昌庙嘴长江大桥大体积混凝土温度控制

Temperature Control for Large Volume Concrete of Miaozui Changjiang River Bridge in Yichang

宜昌庙嘴长江大桥工程桥塔墩承台及锚碇均为大体积混凝土结构,为防止施工过程中结构出现危害性裂缝,对其进行温度控制。基于现行规范和设计要求,提出可行的温控控制标准,采用MIDAS水化热模块计算混凝土的温度场和应力场,根据计算结果及相关经验制定冷却水自循环控制系统及其它混凝土表面养护和内部降温等措施,温控过程中布置温度测点实时监测混凝土内、外部的温度,并与计算值进行对比。结果表明,混凝土浇筑体最高温度值、里表温差、降温速率等温度控制指标均满足设计和规范要求,该桥采用针对性强、科学合理的控制措施,有效地降低了大体积混凝土内外温差,在已完成的各桥塔墩承台及锚碇基础部分均未发现明显裂缝。

The pile caps of pylon piers and anchor blocks of Miaozui Changjiang River Bridge in Yichang are all large volume concrete structures .In order to avoid the occurrence of hazardous cracks in the structure during the construction process ,temperature control was conducted for the bridge .Based on the current codes and design requirements ,the applicable temperature control in-dexes were put forward .The MIDAS hydration heat modulus was used to calculate the tempera-ture and stress field of concrete .According to the calculated results and relevant experience ,the cold water self-circulating control system and the measures for concrete surface maintenance and internal cooling were determined .During the temperature control process ,the temperature testing points were laid out to do real time monitoring and control of the temperature inside and outside the concrete .The measured results were compared with the calculated ones .The results indicate that the temperature control indexes ,such as the maximum temperature value of concrete struc-tures ,inner and outer temperature difference and temperature decreasing rate can meet the design and code requirements .The temperature control measures for the bridge are proved targeted ,sci-entific and rational ,which effectively reduced the temperature difference inside and outside the large volume concrete structures .No obvious cracks were found on the pile caps and anchor block foundations of each pylon .