Predictive Model of Temperature Regimes of a Concrete Gravity Dam during Construction: Reducing Cracking Risks

Abstract

In consideration of the mild climatic conditions of North Vietnam with average monthly air temperatures ranging from 15 °C in winter to 26.5 °C, this study analyzes the regulation of the temperature regime and thermally stressed state of a concrete gravity dam made of rolled concrete. Despite the favorable weather conditions, there remains a risk of thermal cracking, necessitating the presentation of crack-formation models from different countries to assess and mitigate the risk of cracking through the adjustment of construction conditions. The study has developed a predictive model for the temperature regime and thermally stressed state of a layer-by-layer concrete mass under the given construction conditions using the factor-analysis method. Regression equations were then derived from the factorial experiment to quantify the responses of the maximum temperature and maximum stress in the concrete mass. The numerical finite-element method using the Midas Civil software package was employed to calculate the temperature regime and thermally stressed state of the concrete mass. To validate the mathematical predictive model, it was tested on the Ban Lai gravity dam in North Vietnam. The dam, which was constructed from rolled concrete and stands 56 m tall, was selected as the object in this practical example. The results obtained from applying the predictive model were compared to the results obtained from numerical calculations of the dam under construction, as well as the findings from field observations. These results were found to be in good agreement, indicating the effectiveness of the predictive model. Furthermore, an evaluation of the potential for temperature cracking of the concrete during the construction period was conducted.

Study on Temperature Control and Cracking Risk of Mass Concrete Sidewalls with a Cooling-Pipe System

“…Notably, as the temperature increases, the aging rate of the concrete accelerates, resulting in a gradual reduction in the creep rate. Accounting for the influence of temperature on the viscoelastic strain, the equivalent time t e is substituted for the actual time t in Equation (18). The flow strain ε f represents the fully irrecoverable creep strain, and the rate of viscous flow strain is as follows:…”

“…This approach ensured that the concrete humidity and temperature were meticulously regulated to prevent the formation of cracks due to inappropriate artificial maintenance practices. In addition, many prediction models were proposed to guide mass concrete construction to reduce the crack risk, which can predict the temperature and stress state of mass concrete structures [18][19][20].…”