基于车激动力响应互相关指标的桥梁基础冲刷诊断方法

To resolve the problems of existing techniques of bridge foundation erosion diagnosis and detection, such as complex detection procedures, high cost, and great environmental impact, a new method based on the cross-correlation index of vehicle excited response was proposed. This method established a scouring diagnosis system by analyzing the cross-correlation of the attenuation signals, which was a part of the longitudinal acceleration response, between observation points located on the bridge pier or mid-span of the girder under vehicle braking excitation. The aim was to determine the scour position and detect whether the scouring is uniform. First, an initial scouring diagnostic was performed for the entire bridge based on the cross-correlation function amplitude vector assurance criterion. Then, the scouring position was determined by the change rate vector of the cross-correlation function amplitude, and the evenness of foundation scouring was diagnosed through the change rate vector of the cross-correlation function amplitude in the transverse bridge direction. A statistical evaluation method to improve the diagnosis accuracy was used. Finally, a numerical simulation containing various scouring conditions was implemented to verify the reliability of this method based on a real continuous girder bridge. The results show that this method can effectively identify the scouring location and evenness. Diagnostic indices are sensitive to scouring damage. In addition, the influence of signal noise on diagnostic accuracy can be eliminated by using multi-index comprehensive evaluation. Compared with traditional diagnostic methods, it has the advantages of robustness and high accuracy of diagnosis results, simple and easy process, no necessity to perform complex modal recognition that may cause large errors, and allowing the variation of test parameters and conditions. Additionally, it can be embedded in conventional bridge load tests and carried out simultaneously with the load test, which has good engineering application potential and practical value.