Research On Non-destructive Testing Method Of Bolt Anchorage Quality Based On CEEMD Signal Processing Technology

The technology of bolt anchorage is widely used in engineering.It can prevent the deformation of structure and keep the stability of structure by using the anchor age force of bolt.The length of bolt and the compactness of anchoring agent directly determine the anchorage force of bolt.The anchor engineering of bolt is a concealed engineering.So it is particularly important to detect the anchoring quality of bolt.At present,nondestructive testing of the anchoring quality of bolt by stress wave method is the most commonly used method.Because the collected stress wave signal will be accompanied by a lot of noise interferenc e,which is very difficult to judge the length of bolt and the location of grouting d efects.Therefore,the research of a more reliable signal processing method for non-destructive testing of bolt anchorage quality has important engineering application value and theoretical significance.Firstly,in order to analyse the propagation law of stress wave in anchorage system,the propagation,reflection and attenuation law of stress wave in anchorage system were summarized through the study of wave theory and stress wave equation.At the same time,based on the finite element software ANSYS/DYNA,the anchorage models of different anchorage state were established and solved,and the corresponding reflection wave curve was obtained,from which the length of bolt and the location of defect were studied,and the reflection curve characteristics of different pulse widths and different receiving points were studied to guide the actual detection work.Secondly,through reviewing the traditional time-frequency analysis methods,the non-stationary signal processing methods EMD and its variants EE MD and CEEMD were introduced.And a synthetic signal was used to verify the superiority of CEEMD.Based on CEEMD,the traditional HHT method was improved.The improved method overcame the shortcomings of the original method and ha d higher time-frequency resolution.Then it was attempted to apply it to anchor quality information.The length of anchor bolt can be easily judged from the result.Then,based on CEEMD time-frequency analysis principle,the idea of improving the hardware of bolt tester was put forward.By using the new equipment to test the anchor bolt and soil medium bolt,the results showed that the new equipment based on CEEMD time-frequency analysis method had good reliability,and it was found that the supermagnetic source has better excitation effect than the small hammer.Through the test of different anchorage defect PVC pipe models,and using CEEMD time-frequency analysis method,the reflected waves of different models were obtained.The time-frequency analysis results of CEEMD had higher judgment,and the analysis results were in good agreement with the numerical simulation results and theoretical analysis.Finally,the reliability of the new type of anchor detection equipment based on CEEMD time-frequency analysis method in practi cal engineering was verified by sampling detection of the slope anchor of the Silan Expressway under construction in Yunnan Province.