In the frosty expanses of Qinghai, China, a cutting-edge dam project is pushing the boundaries of engineering, revealing crucial insights that could reshape the future of hydropower in cold regions. The NG reservoir, an asphalt concrete core rockfill dam, has become an unexpected classroom for engineers, offering lessons that could enhance the safety and efficiency of similar projects worldwide.
Asphalt concrete core rockfill dams are celebrated for their superior impermeability and adaptability, making them an attractive option for hydropower projects. However, the harsh realities of high-altitude construction have presented unique challenges. During the construction of the NG reservoir, engineers observed something peculiar: the vertical strain in the core wall shifted from compressive to tensile, raising alarms about potential seepage and safety issues.
Min Yuan, a researcher at the Changjiang River Scientific Research Institute, led a study to unravel this mystery. The findings, published in a recent issue of Advances in Civil Engineering, shed light on the complex interplay between temperature and tensile strain in these structures.
The team developed a sophisticated temperature-dependent finite element model, calibrating it to keep deviations between simulated and observed data within roughly 5%. Their simulations revealed that when the ambient temperature hovers around 0.56°C and the asphalt’s initial temperature is 147°C, constrained cooling can produce tensile strains exceeding 500 με (microstrain). Over prolonged intervals, these strains may even reach 900 με near the surface, risking cracks and compromising the dam’s integrity.
“When the annual mean temperature is below 7.6°C and no additional insulation measures are adopted, the asphalt core wall becomes prone to tensile failure,” Yuan explained. This finding underscores the need for real-time strain and temperature monitoring, alongside computational modeling, to mitigate excessive tensile deformation.
The implications for the energy sector are significant. As countries strive to expand their renewable energy portfolios, hydropower remains a critical component. However, many potential sites are located in cold regions, where the challenges observed at the NG reservoir are likely to recur. This research provides a roadmap for navigating these challenges, ensuring the safe and efficient operation of future dams.
The study’s findings could also influence the design and construction of other infrastructure projects in cold regions, from bridges to buildings. By understanding and mitigating the risks of tensile strain, engineers can create more resilient structures, reducing maintenance costs and enhancing public safety.
As the global push for renewable energy intensifies, the lessons learned at the NG reservoir could prove invaluable. By embracing real-time monitoring and advanced computational modeling, the energy sector can overcome the challenges of cold-region construction, paving the way for a more sustainable and secure energy future.
