严寒地区大坝混凝土降温速率研究

Study on cooling rate of dam concrete in severe cold region

针对严寒地区大坝混凝土的降温速率问题,以丰满水电站碾压混凝土重力坝为例,采用有限元法进行仿真分析计算,研究了降温速率的作用及其影响因素。研究结果表明:通水冷却、表面保护、体型及环境温度均会对降温速率造成较大的影响,继而影响混凝土温度应力的发展:增大早期降温速率可以减小后期温度应力,但存在早期开裂风险。然而,减小中后期降温速率可以充分利用徐变和强度,减小开裂风险。

Aiming at the cooling rate of dam concrete in severe cold region, the effect and its influencing factors of the cooling rate are studied herein with a simulation analysis made by the finite element method by taking the roller-compacted concrete gravity dam of Fengman Hydropower Station as the study case. The study result shows that all the factors of water cooling, surface protection, dam body shape and environmental temperature can largely impact the cooling rate, and then influence the development of the thermal stress of the concrete, i. e. increasing the early cooling rate can reduce the thermal stress in the later period, however, the risk of the early cracking is to be there. Nevertheless, reducing the cooling rate in the medium-later period can fully utilize the concrete creep behavior and strength development to reduce the cracking risk.