Abrasion Damage Estimation of Sediment Bypass Tunnels: Validation and Comparison of two Prediction Models

Abstract

Two abrasion prediction models developed for hydraulic structures prone to supercritical flows are compared herein: The models by Ishibashi (1983) and Auel et al. (2015). Both models are compared and validated using prototype data from the Asahi sediment bypass tunnel in Japan. The prediction model by Ishibashi (1983) con-tains some inconsistences in its grinding stress term being much higher than its particle impact term which contra-dicts statements by other researchers. However, it is shown herein that the model leads to good results if only the particle impact term is considered. The prediction model by Auel et al. (2015) shows good performance if the abrasion coefficient kv is adjusted to prototype measurements. The analysis presented herein leads to the conclu-sion that kv for concrete is lower than 106 being a widely accepted value for bedrock abrasion. Independent of the prediction model, utmost interest has to be laid on the estimation of the sediment transport. The theoretical transport capacity may be much higher than the real transport and should be calibrated using prototype field da-ta such as reservoir bed topography surveys.