寒冷地区特高拱坝混凝土最高温度控制研究:以东庄拱坝为例

Research on the concrete maximum temperature control of extra high arch dam in cold regions:A case study of Dongzhuang Arch Dan

【目的】东庄特高拱坝位于北方寒冷地区,与国内其他已建200 m以上特高拱坝主要位于西南气候温和地区存在明显差异,混凝土温度控制难度大。为保证工程建设安全的前提下满足进度和质量要求,【方法】针对东庄大坝建设期夏季和冬季不同季节的控制最高温度标准,基于现场环境气温特性,建立有限元仿真分析模型,采用施工过程仿真技术对东庄拱坝不同冷却龄期、不同基础温差条件下的混凝土温度应力进行研究,将现场监测分析结果与仿真分析规律进行对比分析,提出了相应的最高温度控制建议。【结果】结果显示:为保障拱坝混凝土应力安全,最高温度不应高于26℃;为保障拱坝横缝可灌性,最高温度不应低于20℃。缝开度和温控防裂是一个需要协调的关系,基础温差增大,相应地,温度应力增大、开缝宽度变大、温控措施压力增大;基础温差降低,相应地,应力减小、开缝宽度降低、温控措施压力变小,但是存在缝开度不满足要求的风险,尤其在寒冷地区冬季施工最高温度较低,最终导致缝开度较小无法实现接缝灌浆工作。【结论】综合考虑以上两方面影响因素,给出了大坝混凝土最高温度控制的上限值和下限值,区间范围内最高温度的控制即可以满足接缝灌浆和防裂目的。计算成果可为拱坝施工过程的接缝灌浆温控方案调整提供技术支撑。

The Dongzhuang Extra High Arch Dam is located in the cold regions of the northern China,and there is a significant difference between it and other existing ultra high arch dams over 200 meters in China,which are mainly located in the mild climate areas of the southwest,making concrete temperature control difficult.In order to ensure the safety of engineering construction and meet the requirements of progress and quality,[Methods]a finite element simulation analysis model is established based on the temperature characteristics of the on-site environment during the construction period of Dongzhuang Dam in different seasons of summer and winter.The Construction process simulation technology is used to study the temperature stress of concrete in Dongzhuang Arch Dam under different cooling ages and foundation temperature differences,Compare and analyze the on-site monitoring analysis result with the simulation analysis rules,and propose corresponding suggestions for maximum temperature control.[Results]The result show that in order to ensure the stress safety of the arch dam,the maximum temperature should not exceed 26℃.To ensure the groutability of the transverse joints of the arch dam,the maximum temperature should not be lower than 20℃.The relationship between joint opening and temperature control crack prevention needs to be coordinated.As the temperature difference increases,the temperature stress increases,and the width of the joint increases.The pressure of the temperature control measures increases,while the temperature difference decreases.The stress decreases,and the width of the joint decreases.However,there is a risk that the joint opening does not meet the requirements,especially in cold regions where the highest temperature during winter construction is low,which ultimately leads to a smaller joint opening and the inability to achieve joint grouting work.[Conclusion]Taking into account two factors comprehensively,the upper and lower limit values for the maximum temperature control of the dam are given.The control of the highest temperature within the interval can meet the requirements of joint grouting and crack prevention.The calculation result in this article can provide technical support for adjusting the temperature control scheme of joint grouting during the construction process of arch dams.