Stress Wave of Micro NPR Bolt under Shear State Based on Empirical Mode Decomposition method

When micro NPR bolt is supporting slope, different shear Angle has influence on the quality of bolt anchoring support. Based on the model, we studied the time-domain signal characteristics of the micro NPR bolt after shearing. Furthermore, we study the influence of shear Angle on the supporting effect of bolt. The results show that the transmission and velocity characteristics of L(0,1) mode increase with the decrease of shear Angle in the bending model. Overall, the potential of guided waves for bending rod detection and monitoring is positive. When the stress wave passes through the shear part of the anchor bolt, it will be reflected and refracted, and the mode transformation will occur, and bending echo F(1,1) will appear. When the bending position is fixed, the shear Angle linearly increases, the degree of bolt bending deformation also increases, and the relative amplitude of modal transformation at the elbow also increases. Moreover, the IMF2 component decomposed by EEMD has a certain relationship with the bending wave, which is helpful for our future intelligent method identification of micro-NPR bolt shear Angle.