高寒地区混凝土坝高温度峰值区域的温控防裂

Analysis on temperature control and crack prevention within high temperature peak area of concrete dam in alpine region

高寒地区由于年平均温度较低等原因,强约束区域混凝土温度峰值过高时容易开裂,因此高寒地区混凝土坝强约束区在低温季节或在高温季节浇筑需采取严格的浇筑温度控制措施以控制浇筑温度峰值。一些情况下混凝土浇筑过程中可能出现温度峰值没有得到较好控制的情况,这些坝体或坝块在运行期间的温控防裂问题需要深入研究。为此,以西部高寒地区某大型水电工程为例,采用有限元分析和监测数据进行坝体温度场重构和应力场分析,并对温度应力规律进行总结和分析,研究混凝土坝强约束区在浇筑温度难以得到控制情况下的温控防裂措施。结果表明,在浇筑温度明显超标的情况下,浇筑初期和越冬季节采取严格的保温措施和在蓄水前采取有效的裂缝修复措施,可以有效地防止运行期温度裂缝的产生和扩展。通过采用以上温控措施后,该坝顺利通过了蓄水验收并成功蓄水,没有出现温度裂缝的发生和进一步扩展和渗漏情况。研究成果可为高寒地区混凝土温控防裂提供指导。

Due to the low annual average temperature in alpine region,the concrete in strong constraint area of the dam body therein is prone to crack when the peak value of its temperature is too high,and then strict temperature control measures are necessary to be adopted for the concrete placement in the strong constraint area of the concrete dam in alpine region during low-temperature season or high-temperature season,so as to control the peak value of the placement temperature.In some cases,the situation that the temperature peak value is not better controlled is to occur during the concrete placement,for which the temperature controls and crack preventions of those dam bodies or dam blocks must be deeply studied.Therefore,by taking a large scale project in the alpine region in Western China as the study case,the reconstruction of the temperature field and the analysis of the stress field of the dam are carried out with finite element analysis and the relevant monitoring data,while the law of the temperature stress is summarized and analyzed for studying the relevant temperature control and crack prevention measures under the condition that the concrete placement temperature is difficult to be controlled within the strong constraint area of concrete dam.The results show that the occurrence and propagation of the temperature crack during the operation period can be effectively prevented through adopting both strict thermal insulation measures during the initial concrete placement and the over-winter season and the effective crack repairing measures before the impoundment of the reservoir under the condition of the obvious over-standard of the placement temperature.Through adopting the temperature control measures mentioned above,the dam is not only successfully passed through the reservoir impounding acceptance,but also is successfully impounded without occurrence and further propagation of temperature crack as well as the relevant leakage.The study results can provide some references for the temperature control and crack prevention of the concrete in alpine region.