The wear of cutter is an important factor affecting the efficiency of shield tunneling

which is also a basis for determining the time and frequency of cutter replacement. As it is difficult to evaluate the overall wear state of the cutters in the process of shield tunneling

three wear degrees (light

moderate

and severe) were proposed based on the relationship between the wear amount of each cutter and the limited wear at the cutters change site. The theoretical relationship between three main tunneling parameters (thrust

torque

and tunneling speed) and the cutting force component of a single cutter was derived

and a method for recognizing the overall wear state of cutters was proposed by using the wavelet packet algorithm to decompose the tunneling parameter signals. In this method

the eigenvectors composed by the standard deviation of the wavelet packet coefficient of decomposed signal nodes were used as the wear recognition index. Sensitivity analysis was performed to find out the most sensitive node eigenvector of the cutter wear. Then the functional relationship between the wear state and the wear recognition index was determined by fitting. The analysis of the section from Dayun station to Baohe station of Shenzhen Metro Line 14 showed that the method could accurately recognize the overall wear state of the shield cutters. Among the three tunneling parameters

the recognition accuracy was the highest when using the tunneling speed signal

followed by the thrust signal

and the torque signal was the lowest. The proposed method is easy to use and cost-effective

since it only needs to analyze the automatically collected tunneling signals without installing any sensors

which provides reference for cutter replacement.