高寒区堆石混凝土一体化厚层浇筑坝体温度研究

Study on temperature of rock-filled concrete dams under integrated thick-layer placement in high-altitude cold regions

摘要

【目的】低水化热温升和施工速度快的堆石混凝土(Rock-Filled Concrete, RFC)筑坝技术契合了高寒区的筑坝需求，针对其在高寒区建设过程中的仓内温度变化情况进行现场监测可为其在高寒区的设计建设提供基础资料与参考依据。【方法】为研究高寒区RFC坝在一体化厚层浇筑下的坝体温度变化与分布规律，对叶巴滩二道坝(坝顶高程2 730.0 m)的坝体温度展开了现场跟踪监测，累计在13个施工仓面内布设了83个温度测点。【结果】结果显示：抗冲耐磨层自密实混凝土(Self-Compacting Concrete, SCC)的水化热温升均值为24.77℃,显著高于坝体RFC的10.94℃;当浇筑层厚增加0.5 m时，C25-RFC的水化热温升均值的变化幅度仅为0.02℃,而C30-SCC则从24.33℃增加到27.24℃,上升了近3.0℃;堆石内部测点(30 cm深)与堆石外部测点(5~15 cm)的入仓温度与水化热温升度数相差不大，且会随时间推移逐渐趋于一致。【结论】结果表明：(1)在高寒区抗冲耐磨一体化通仓厚层浇筑的情况下，坝体局部高温、高温度梯度区一般会分布在上下游抗冲耐磨层表面；(2)浇筑层厚的适当增加，对坝体RFC水化热温升幅度影响较小，但对抗冲耐磨层SCC的影响较大；(3)当混凝土标号和浇筑层厚一定时，抗冲耐磨层的水化热温升度数相对稳定，可通过调整入仓温度来使其峰值温度满足设计要求。

Abstract

[Objective] Rock-filled concrete(RFC), characterized by low hydration heat temperature rise and rapid construction speed, meets the dam construction requirements in high-altitude cold regions. On-site monitoring of temperature variations inside the lifts during the construction in high-altitude cold regions can provide basic data and references for its design and construction in such environments. [Methods] To investigate the temperature variations and distribution patterns of RFC dam regions under integrated thick-layer placement in high-altitude cold regions, on-site tracking and monitoring were conducted on the Yebatan secondary dam(crest elevation: 2 730.0 m), with a total of 83 temperature measurement points deployed across 13 construction lifts. [Results] The results showed that the average hydration heat temperature rise of the self-compacting concrete(SCC) in the erosion-resistant layer was 24.77 ℃, significantly higher than the 10.94 ℃ of the RFC in the dam body. When the placement layer thickness increased by 0.5 m, the average hydration heat temperature rise of C25-RFC changed by only 0.02 ℃, while that of C30-SCC increased from 24.33 ℃ to 27.24 ℃, a rise of nearly 3.0 ℃. The placement temperature and hydration heat temperature rise showed minimal differences between internal(30 cm deep) and external(5~15 cm) measurement points in rock-filled concrete, with values gradually converging over time. [Conclusion] The findings reveal that:(1) under integrated thick-layer placement of erosion-resistant layers in high-altitude cold regions, local high-temperature zones and steep temperature gradients are typically distributed on the upstream and downstream surfaces of these layers.(2) A moderate increase in placement layer thickness has little effect on the hydration heat temperature rise of the RFC dam body but has a significant effect on the SCC in the erosion-resistant layers.(3) When the concrete grade and placement layer thickness remain constant, the hydration heat temperature rise of the erosion-resistant layers is relatively stable, and the peak temperature can be controlled by adjusting the placement temperature to meet design requirements.

关键词

高寒区 / 堆石混凝土 / 一体化厚层浇筑 / 坝体温度 / 抗冲耐磨层 / 影响因素

Key words

high-altitude cold region / rock-filled concrete / integrated thick-layer placement / dam body temperature / erosion-resistant layer / iufluencing factors

基金资助

国家自然科学基金重点项目(52039005)