Optimization scheme of water irrigation and electric heating method for multi-crack detection in wading-concrete structures

Abstract

Underwater concrete structures face significant challenges due to their complex living environment, among which cracks are a critical factor. According to the fundamental principles of water irrigation and electric heating method, we introduced a novel approach that leveraged the cooling law of the point heat source in the monitoring tube to estimate the flow velocity along the irrigation pipe, to further detect cracks based on the variations in axial flow velocity. Numerical simulations were initially conducted to investigate the effects of factors such as the size effect, flow velocity along the irrigation pipe, combination scheme of the monitoring tube and irrigation pipe, and heating power on the cooling law of the heat source, to further determined an optimized monitoring scheme. A series of model tests was then conducted based on this optimized scheme. First, the relationship between cooling discrimination index and axial flow velocity was calibrated. Then, by adjusting the water pressure, the leakage rates under different crack widths could be obtained, allowing for the derivation of a fitting formula to estimate the crack width using the water pressure and leakage rate. Finally, in double crack specimen, the proposed multi-crack identification method, along with the calibration relationship and fitting formula, was used to perform the crack inversion. The inverted crack widths showed good agreement with the actual crack widths, with an RMSE value of 0.0212 mm.