Numerical Study on Seismic Wave Field of Shaft Boring Machine in Rock Layer Interface with Different Dip Angles

Shaft boring machine is the development direction and trend of comprehensive mechanized shaft sinking. Advanced geological exploration based on the seismic wave field of the rock-breaking source of the shaft boring machine is an effective method to ensure the construction safety of the shaft boring machine. In order to study the seismic wave field characteristics of rock-breaking source of shaft boring machine, taking the rock stratum interface of common geological conditions as an example, the geological model of rock stratum interface with different dip angles is established by using the full wave field numerical simulation software Tesseral. The continuous random signal is used as the rock-breaking source for forward calculation, and the seismic wave field of the rock-breaking source of the shaft boring machine is obtained. Taking the strata without interface as the reference group, the direct wave in the seismic wave field is removed, and the reflected wave, diffraction wave, etc., are obtained in the seismic wave field. The time domain characteristics of the reflected wave are analyzed, and the frequency domain characteristics of the reflected wave at the interface of each rock layer are compared through wavelet packets. The results show that: The dominant frequency of the reflected wave in the seismic wave field at the interface of different dip strata is in the range of 50~200 Hz, and the component and dominant frequency of multiple waves are relatively complex, which are distributed within 600 Hz. With the increase of the dip angle of the rock stratum interface, the smaller the propagation distance of the wave, the earlier the arrival time of the reflected wave, and the greater the amplitude. The energy of each dip angle is concentrated between 70~125 Hz. As the dip angle of the rock stratum interface increases, the energy value of the reflected wave at each dip angle increases, while the energy proportion of the low-frequency component decreases. The main frequency of the seismic source has a relatively small impact on the time-domain and frequency-domain characteristics of the reflected waves at the interfaces of various rock layers. The geological conditions have a significant impact on the time-domain and frequency-domain characteristics of the reflected waves at the rock layer interface. The maximum amplitude and energy of the reflected waves in the upper soft and lower hard geological conditions are much greater than those in the upper hard and lower soft geological conditions. The energy proportion of the low frequency band of the reflected waves in the upper soft and lower hard geological conditions is relatively small. The research results provide a reference for the theoretical understanding of the seismic wave field of the rock-breaking source of the shaft boring machine.