Dams & Hydro
Geotech
Advanced Numerical Analysis
Validated Finite Element Modelling of the Thermodynamic Operating State of KATSE DAM
SANCOLD 2024 ANNUAL CONFERENCE 6-7 November 2024
By Ryan Cassells, ARQ Dams Pty Ltd
-co-author L Hattingh, Hatting Anderson Associates CC, Woodhill, South Africa
-co-author Prof P Moyo Department of Civil Engineering, University of Cape Town, South Africa.
The structural response of large concrete arch dams under operating conditions, are significantly influenced by the seasonal thermal loading conditions of the dam. Regression analysis of the deformation behaviour of Katse Dam has indicated that this is especially true for Katse Dam which is exposed to extreme ambient temperature conditions of -5˚C to 30˚C.
The Katse Dam is a 185 m high double-curvature arch dam located in Lesotho forming part of the Lesotho Highlands Water Project. Due to the high altitude of the dam, the surrounding mountainous topography and resulting continental climate conditions, the dam is exposed to extreme climate with hot Summers and very cold Winters. As a result of the thermal expansion coefficient of concrete, raised temperature conditions cause the arch dam to expand and tilt upstream, whilst cold conditions cause the dam to shrink and tilt downstream.
The dam safety evaluation of Katse Dam as conducted by the 2019 panel of experts (POE), proposed that a comprehensive three-dimensional finite element (FE) structural analysis be undertaken of the dam, using current state-of-the-art numerical modelling technology. To ensure the reliability of this complex analysis, the FE model created was first calibrated against the observed behaviour of the dam as reported by instrumentation installed in the dam body. One of the calibration objectives was to validate the heat transfer behaviour of the thermodynamic component of the FE model.
This paper looks at the thermodynamic calibration of the Katse Dam FE model. The process involves calibrating heat flow mechanisms and heat exchange boundary conditions of the FE model, so that the computed operating time-based temperature state closely represents the actual temperature state of the dam body.
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