Non-destructive test method of rock bolt based on D-S evidence and spectral kurtosis

The length of the rock bolt is an important factor 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, and improve accuracy of calculating anchor length. The fundamental idea is that calculating spectral kurtosis for each component after EMD, the larger spectral kurtosis are used to reconstruct signal to improve signal to noise ratio. The analysis results demonstrate that the method can improve spectral kurtosis of the reconstructed signal and decrease the error of anchor length. In addition, D-S evidence is introduced to realise high precision computation for anchor length by data fusion of wavelet threshold de-noising and spectral kurtosis filter.