Abstract: In mining engineering geology, there are often faults and goafs. The law of the microseismic signal propagation through faults and goafs is bound to change, so it is important to study the propagation law of the microseismic signal in special geological structures. Based on the Huygens principle, the wave surface equation of microseismic waves in non-uniform medium conditions is established by considering the different propagation velocities of microseismic waves in different layered rock masses. Then the relationship between the wave surface radius and the incident angle is obtained. By combining with indoor similar material model experiment, the applicability of the wave surface equation is verified, and the influence characteristics of faults and goafs on the propagation of the microseismic signal are also summarized. The results show that the microseismic signal takes longer to cross the fault, and the presence of the fault causes a larger attenuation of the signal energy (maximum vibration velocity). The microseismic signal will continue to propagate at the original velocity after passing through the fault, and the attenuation of the signal energy does not lead to the attenuation of the propagation velocity of the microseismic signal. The larger the incident angle of the microseismic wave passing through the fault, the longer the time to pass through the fault, and the more the attenuation of the signal energy. The existence of the goaf gives rise to the attenuation of the propagation velocity of the microseismic signal, and the closer the distance between the seismic source and the monitoring point, the greater the influence of the goaf on the relative propagation velocity of the microseismic signal.

Key words: wave surface equation, fault, goaf, propagation law