Computational optimisation and modelling of sacrificial anode placement and dimension for maximising the corrosion prevention of screw piles

Abstract

Cathodic protection (CP) is widely used to mitigate corrosion and protect the substrate. However, sacrificial anodes are often undersized or improperly positioned. This study systematically investigates how anode design factors affect the CP effectiveness through computational modelling and double-objective optimisation techniques around the optimum location and dimension of anodes. State-of-the-art algorithms including the Monte-Carlo, Nelder–Mead, co-ordinate search, constrained optimisation by linear approximation (COBYLA) and bound optimisation by quadratic approximation (BOBYQA) are employed to optimise anode locations and genetic algorithm is utilised for optimising anode dimension and the objective is maximising the current output and minimising the cost. In the current study, the BOBYQA technique proved efficient in reaching the optimal response at the appropriate time. The findings indicate that in double-objective (cost and potential) optimisation of 14.5 kg anode, minimising anode radius (from 6.5 cm to 5.4 cm) and optimising the position boosts the current output by up to 15.5%. Refined anode geometries increase the average structure potentials (806 → 822 mV) by over 15 mV, translating to extended service lifetimes. In the comparison of single (cost) and double (cost and potential)-objective optimisation, about 15% more current reaches the structure and causes about 2% less anode mass loss for the same anode dimensions. Also, the results show the 7.7 kg anode performs better than the 14.5 kg anode and so output current and the percentage of current that reaches the structure of the 7.7 kg and 14.5 kg are 0.66 A and 0.46 A and 66% and 60%, respectively.