【摘要】 现有大体积混凝土温控研究主要强调对内部最高温度以及温差的控制,而对降温阶段的起始时间以及容许降温速率的研究较少,导致严寒地区某些工程在完善的温控措施下仍然存在不同程度的开裂。以丰满水电站工程为例,采用容许降温速率评价大体积混凝土的开裂风险,利用有限元仿真分析软件对不同龄期混凝土的容许降温速率进行研究,分析降温速率对温度应力的影响作用,研究不同阶段的降温速率控制指标。研究结果表明,容许降温速率与混凝土相应龄期的抗力关系密切。针对丰满水电站大坝混凝土,建议早期降温速率在0.65℃～1.20℃,中期降温速率在0.40℃～0.60℃,后期降温速率要低于每天0.30℃,以降低开裂风险。更多还原

【Abstract】 The existing studies on temperature control of massive concrete mainly emphasize on controlling of internal peak temperature and temperature difference, but the studies on the start time of cooling stage and the cooling rate are insufficient, resulting in that several projects in severe cold region cracked in different degrees even under perfect temperature control. Taking Fengman hdyroproject as an example, the cracking risk of massive concrete is evaluated through allowable cooling rate. The allowable cooling rates of the massive concrete at different ages are studied by finite element simulation software and the effect of cooling rate on the temperature stress is analyzed. With the analysis results, the controlling indexes of cooling rate at different stages are put forward. The results show that the allowable cooling rate is closely related with the resistance capacity of concrete. For the Fengman Hydropower Project, to reduce cracking risk, it is suggested that the cooling rate at early age should be between 0.65℃～1.2℃/d, and 0.4℃～0.6℃/d in middle stage, and less than 0.3℃/d in the later stage.更多还原