Non-destructive test method of rock bolt based on improved spectral kurtosis

The length of the rock bolt is an important factors to evaluate the quality of anchor. According to the fact that the calculated value of anchor length is far different from the actual situation due to a lot of noises, a de-noising method based on Empirical Mode Decomposition (EMD) and Spectral Kurtosis (SK) is proposed in this paper, to filter noise, increase SNR and improve accuracy of calculating anchor length. First, measured signal is decomposed by EMD to contain a finite number of stationary intrinsic mode functions (IMFs). Then, average spectral kurtosis for each component is calculated. Finally, using the filtering function of the spectrum kurtosis, the IMF components with larger spectrum kurtosis are chosen to reconstruct signal. The analysis results demonstrated that the method can filter out the noise and the error of calculated anchor length is less.