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

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.

Keywords

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