Temperature control and crack prevention scheme of low heat cement concrete arch dam in high cold area
- Article
- Figures
- Metrics
- Preview PDF
- Reference
- Related
- Cited by
- Materials
Abstract:
The frigid regions were characterized by low annual average temperatures and significant diurnal temperature variations, which made it prone for dams to develop temperature cracks. The conventional high concrete arch dams at that time utilized a mix of "moderate heat Portland cement with 35% Class I fly ash". Despite achieving the then-current advanced level of temperature control measures, the safety factor for concrete crack resistance remained at approximately 1.8. Consequently, it was imperative to conduct research on temperature control and crack prevention, starting from the very source of the materials. With the concrete double-curvature arch dam of a hydropower station in Xizang as its research backdrop, low-heat cement concrete was chosen as the dam-building material. By reducing the temperature rise from the source of the material, it aimed to further mitigate the risk of cracking. Drawing upon the theories of unstable temperature and stress field calculations, a comparative analysis of the temperature and stress fields between moderate-heat and low-heat cement concrete arch dams was conducted, highlighting the advantages of using low-heat cement concrete for dam construction. Following this, it optimized and compared various temperature control measures for low-heat cement concrete arch dams, ultimately formulating a tailored temperature control and crack prevention strategy suitable for frigid regions. The results indicated that the maximum temperature of the low-heat cement concrete arch dam was approximately 4.0℃ lower than that of the medium-heat cement concrete dam, and the maximum stress was reduced by about 0.7 MPa. Moreover, the safety factor was elevated from 2.48 to 3.65. For low-heat cement concrete arch dams, the spacing of water cooling pipes in the constrained zone could be relaxed to 1.5 m×1.5 m, and the thickness of the pouring layer in the strongly constrained zone could be increased from 1.5 m to 3.0 m. The water flow measures on the dam surface could be eliminated, and the pouring temperature in summer could be relaxed to 16.0 ℃, allowing for normal temperature pouring in winter. Outside the constrained zone, during the high-temperature season from May to September, the pouring temperature could be appropriately increased to 18.0 ℃. The thickness of the layer had a minor impact on the maximum temperature and stress of the dam, permitting an extension to 6 m. The dam adopted permanent thermal insulation throughout the year, with a equivalent heat release coefficient of β≤ 3.05 kJ/(m2?h?℃). These research outcomes validated the superiority of low-heat cement concrete arch dams in crack resistance and provided optimized temperature control measures for frigid regions. They facilitated rapid dam construction while further reducing temperature control and construction costs, offering technical guidance for the application of low-heat cement in frigid regions.
Keywords:
Project Supported:
Clc Number:
Mobile website
® 2024 All Rights Reserved
冀公网安备13010502002656号
冀公网安备13010502002656号