Study On The Nondestructive Testing Method Of The Rock Bolt Based On The Theory Of Spectral Kurtosis

With the development of anchorage technology, it has been widely used in construction of slope, bridge and tunnel, etc. But sumequently, quality detection of anchorage engineering is extensively concerned. As the traditional detection method, pull-out test is destructive and has many limits. Nondestructive test technology on bolt is still in the stage of continuous development and improvement. Optimization and improvement for test results still need further study in the aspects of theory and practice. Based on the analysis and summary of development of detection technology for anchor, the theory of spectral kurtosis is applied to non-destructive testing for bolt. This paper focuses on the following:(1) According to the inherent characteristics of anchors, spectral kurtosis is applied to identification of anchor. By defining the range of minimum and maximum of kurtosis spectral, different types of anchors can be classified. According to the limits of this method, K-means clustering algorithm is used for spectral kurtosis automatic clustering to realize identification of different bolt model and improve the accuracy of classification.(2) Using AGI-MG anchor quality detector to test the existing models of anchor, providing large amounts of data for research on nondestructive test. Since spectral kurtosis can reflect the noise to signal ratio, a filter is constructed according to the distribution of spectral kurtosis of measured signal of anchor. The spectral kurtosis theory and EMD decomposition algorithm are combined to reconstruct the signal. Then, the two methods are used to deal with the measured signal and to optimize geometric parameters of anchor.(3) D-S data fusion is adopted based on results of spectral kurtosis filter, EMD and spectral kurtosis and results of wavelet threshold. The accuracy of calculation of bolt geometric parameters has been greatly improved.(4) The cast anchor model is designed and experimental data are collected. According to the experimental data processed by spectral kurtosis filter, effects of different intensity and different pouring length on velocity of anchor are analyzed to measure the anchorage quality and status.