基于车辆制动激励和小波包能量分析的连续梁桥基础冲刷识别方法

In recent years, bridges have frequently failed as a result of scour. Scour will cause the soil around the bridge substructure to be washed away, decreasing the bearing capacity of the bridge foundation. However, the scouring position is concealed, which increases the difficulty of diagnosis. In order to accurately identify the foundation scour of a bridge substructure, the fact that vehicle braking can induce a significant longitudinal dynamic response in a bridge substructure was used to develop a foundation scour identification method for continuous beam bridges based on a wavelet packet energy analysis of the dynamic response under vehicle braking. In this study, the braking force of a typical three-axle vehicle was used as the excitation, the wavelet packet method was used to decompose the response of the acceleration before and after scour in the longitudinal direction of each bridge pier top caused by vehicle braking, and the wavelet packet energy variance variation rate was used as the scour identification index to locate the scour position. Then, a sample database containing various scour degrees and corresponding scour index values was established using numerical simulations. The functional relationship between the scour identification index and scour degree was determined using a fitting analysis, and then the scour degree was quantified and identified by the pattern inversion method. The analysis results of a concrete continuous beam bridge project showed that the method could be used to determine the location and quantitative identification of the foundation scour of a beam bridge with strong anti-noise ability, and the identification results were less affected by factors such as the vehicle weight at a braking position with bridge deck unevenness and the initial speed. The method only requires the installation of an acceleration sensor on the top of the bridge pier during the test process, which can be realized with the help of a conventional bridge load test project. It has the characteristics of a simple and easy test, good accuracy, and so on, and is suitable for the rapid detection of the scour of a highway beam bridge foundation.