Validating Dynamic Identification of Foundation Scour Based on Large-Scale Water Flumes

Recently, bridge collapse accidents have become increasingly frequent during the flooding season, and foundation scour is one of the main reasons. Tracking scour evolution accurately is a key premise for preventing and controlling hydrological damage. Scour identification according to the changing dynamic characteristics during the scouring process tends to be one of the top technical methodologies in scour monitoring. Although efforts have been made to investigate the dynamic identification of foundation scour, the investigations have mainly focused on the qualification of foundation scour utilizing numerical simulations. Quantitative analysis and validation through laboratory experiments with large-scale water flumes are still lacking. To bridge the gap, this study performed physical modeling experiments with a large-scale water flume for foundation scour to investigate the relationship between structural frequency and scour evolution. The research sought to validate the feasibility of using structural frequency in dynamic identification. First, scour experiments with a large-scale water flume for three piers were performed to collect the time history of acceleration signals. Then, the acceleration signals were processed to recognize the temporal evolution of structural frequency during the scouring process. Finally, the relationship between the temporal scour depth and frequency was assumed to be linear and nonlinear to fit the time history of structural frequency. The results indicated that the frequency and the square of frequency can be taken as the dynamic fingerprint in scour identification according to the frequency range. Based on the validation of large-scale flume experiments, the proposed nonlinear temporal models of frequency in the study demonstrated a good indicator for predicting scour depth. The methodology can greatly enhance the practicality and convenience of bridge scour dynamic identification.