160000 m^3大型LNG储罐混凝土外罐施工全过程温度作用分析

Influence factors of thermal stress in the construction period of the concrete outer tank for 160000 m^3 LNG storage

为了解160 000 m3大型液化天然气(LNG)储罐混凝土外罐在施工期间的抗裂性能,避免由于水泥水化放热、混凝土收缩、外界气温变化而造成的外罐墙壁竖向开裂及扶壁柱局部环向裂缝现象,运用有限元数值模拟技术,采用增量法,分别探讨了施工模板材料、施工质量、施工季节及混凝土入模温度对混凝土外罐温度应力分布的影响及其规律.结果显示:模板对温度应力的影响作用较小,混凝土收缩导致混凝土拉应力持续增长,温度应力随着施工季节温度的变化而产生相应波动,施工质量及施工季节对温度应力的影响较大;在上述结论基础上,视温度应力结果为水化热、混凝土收缩、外界气温及入模温度各自单一影响作用下温度应力的叠加,进而总结出各因素对混凝土施工阶段温度应力的影响规律,并提出可供实际工程参考的防裂措施建议.

To investigate the cracking resistance and avoid the vertical and local circumferential cracks at the bottom of the concrete outer tank during the construction period due to hydration heat, concrete shrinkage and temperature changes for 160 000 m^3 liquefied natural gas （LNG） tanks, using the finite element numerical simulation technology, the influence of shuttering material, construction quality, construction season and pouring temperature on cracks was figured out with an incremental method. The results show that concrete shrinkage leads to a sustaind growth of concrete tensile stress, the thermal stress fluctuates according to the changing of construction temperature and construction quality and construction season have a strong inference on cracks. Based on this basis, the thermal tress is dismantled according to the effect of each influencing factor, and the whole thermal stress is the superposition of the thermal stress under single influence of hydration heat, concrete shrinkage, construction season and pouring temperature. Some suggestions on anti-cracking measures are proposed, mainly by regulating the construction season, complementally by improving the quality of construction.