Research on rust expansion cracking analysis and time prediction of the protective layer of cantilever anti-slip piles based on the optimized thick-walled cylinder model

Based on the theory of elastic mechanics and the mechanism of steel bar rust expansion, an analysis model of the initial rust cracking at the rebar- concrete interface of the pile body and the partial cracking of the protective layer was established. The synergistic mechanism of rust, load,and stirrup restraint was analyzed, and a prediction model for the rust expansion and cracking time of the protective layer surface was established. The accuracy of the established prediction model was verified by comparing it with the results of examples and other models. The analysis results show that in terms of the influence degree on the critical corrosion depth, the effect of the external load is greater than the filling effect of the corrosion products and greater than the binding effect of the stirrups. The closer to the reinforcing bars of the pile body, the more severe the damage. ● The thick-walled cylinder model was optimized by introducing factors such as rust products, load action parameters, and hoop constraint effects. ● The analysis models for the initial cracking of the reinforced concrete interface corrosion of the pile body and the local cracking of the protective layer, as well as the prediction model for the time of rust expansion cracking on the surface of the protective layer were established. ● The depth of rust and the distribution law of damage were obtained, and the model was reasonably verified.