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特高拱坝普遍存在封拱后温度回升现象。为清楚认识温度回升的原因、幅度、过程及影响,总结了特高拱坝内部封拱后温度变化情况,采用以后期水冷停水时刻作为起点的混凝土龄期,通过拟合及仿真反馈建立了大坝混凝土后期温升模型。以小湾拱坝为例,采用建立的后期温升模型进行仿真分析,结果显示:(1)后期温度回升主因是混凝土自身发热;(2)小湾拱坝后期温升明显,普遍有6~12℃,上升至最高温度约4~7年,回落至稳定温度约需40年;(3)考虑温度回升时大坝温度荷载与设计温度荷载存在差异,平均温度明显偏高,同时上下游温差减小;(4)后期温度回升使大坝存在整体向上游变形的增量,对坝体各向应力均有影响,坝趾产生拉应力增量,坝踵产生压应力增大,同时内外温差加大,在长期运行过程中可能会带来表面裂缝。
The phenomenon of temperature rise after arch closure is common in the UHV arch dam. In order to understand the reason, amplitude, process and influence of temperature rise, the temperature change after arch sealing in UHV arch dam was summarized. The concrete age was taken as the starting point after water-cooling stoppage time was established, and the fitting and simulation feedback Late stage concrete dam temperature rise model. Taking Xiaowan arch dam as an example, the late-stage temperature rise model was used to simulate and analyze the results. The results show that: (1) the main cause of temperature rise in late stage is concrete self-heating; (2) 12 ℃, up to the maximum temperature of about 4 to 7 years, down to a steady temperature of about 40 years; (3) When considering the temperature rise dam temperature load and design temperature load are different, the average temperature was significantly higher, while the upstream and downstream temperature difference Decrease; (4) Late temperature rise makes the whole increase of the dam to the upstream deformation, which affects the stress in all directions of the dam, the increase of tensile stress in the dam toe and the increase of compressive stress in the dam heel, Increase in the long run may cause surface cracks.