Bayesian-optimization-based inversion analysis for residual hydration heat of a high arch dam

After closure, high arch dams often exhibit a noticeable temperature rise that significantly affects their stress state. This rise is driven by both environmental heat transfer and residual hydration heat of concrete, yet the dominant cause remains under debate. Using temperature monitoring data from the Baihetan arch dam, this study examines the evolution, causes, and structural effects of this process. By October 2024, the Baihetan dam shows a temperature rise of 4.5–9 °C. A detailed analysis reveals a 3–4 °C temperature gradient across the dam thickness at closure within the placement blocks. Previous studies assumed a uniform closure temperature field, which results in a systematic overestimation of residual hydration heat. On this basis, a Bayesian-optimization-based inversion framework is employed to refine the estimation of residual hydration heat, yielding a value of approximately 2.5–3.0 °C. Using a factor-separation approach, the relative contributions of the influencing factors are quantified, showing that environmental effects contribute approximately 60% of the temperature rise, whereas residual hydration heat contributes around 40%. The temperature rise causes upstream deformation and induces local tensile stresses of 0.1–0.4 MPa. These findings offer quantitative insights into the temperature-rise mechanism and support the structural safety assessment of high arch dams.