Study on Nondestructive Testing of Source Factors of Tunnel Arch Quality

To obtain high-energy, high-frequency, and wide-band seismic signals in tunnel arch quality testing, the influence on seismic waves of the mass, velocity, and contact area of the hammer source was studied based on a finite element simulation. The results show that with the increase in mass of the hammer, the amplitude of the hammer signal increases linearly, the main frequency decreases, and the frequency band width increases significantly. With the increase in the instantaneous velocity of the hammering, the amplitude of the hammer signal increases linearly, the main frequency increases slightly, and the frequency bandwidth does not change significantly. With the increase in the contact area between the hammer and the ground, the amplitude of the hammer signal increases, and the main frequency and bandwidth remain basically unchanged, but the energy of the high-frequency component is attenuated and the bandwidth is narrowed. According to the above research, a small integrated round-head hammer was designed and non-destructive testing experiments were carried out, which showed that the hammer could obtain high-quality seismic signals and realize the detection and imaging of the tunnel inverted arch bottom interface, and the imaging results were basically consistent with the actual construction situation. In this work, the study of the seismic source is extended to the field of tunnel arches, and it can provide a reference for nondestructive testing of tunnel arches.