Experimental Study On The Influence Of Faults And Mined-out Areas On Microseismic Signal Propagation And Source Location

Mine production is often accompanied by the occurrence of microseismic events.The precise location of the seismic source has important practical significance for the safety of mine production and disaster prevention and mitigation work.At present,most studies on the location of microseisms are based on the premise of a single rock formation.There are often faults in engineering geology.When microseismic signals propagate through the faults,their propagation laws will inevitably change.If the nature of the rock formation in the mining area is not uniform,using the velocity as a constant to locate the seismic source will usually produce large errors.The mining process is bound to accompany the emergence of goafs.The mined-out area will change the propagation speed of the microseismic signal in the medium,which will eventually lead to inaccurate source location results.In this paper,through a combination of theory and experiment,the influence of layered rock mass interruption and mined-out area on the propagation law of microseismic signals and the location of the source is studied,and the following main conclusions are drawn:(1)Through theoretical derivation and laboratory experiments,the influence of faults on the propagation of microseismic signals has been studied.The results show that it takes a long time for microseismic signals to pass through the fault.The propagation speed of the microseismic signal will not be attenuated;the fault has a stronger hindering effect on the high frequency part of the signal.The greater the incident angle of the microseismic signal when it passes through the fault,the longer it takes to propagate the same distance,and the more the signal's energy attenuates.(2)The influence of the layered rock mass on the source location results of the travel-time residual method and the double-difference method is studied through indoor experiments and numerical calculations,and the objective function is solved by the simulated annealing-pattern search algorithm,and the layered rock mass and sensors are obtained.The law of the influence of the network layout on the positioning results;combined with the derivation of the wave propagation formula in the inhomogeneous medium,it is concluded that the main reason for the positioning error is the difference between the actual propagation distance of the wave and the theoretical value in the homogeneous medium.The size of the positioning error is determined by The angle at which the wave passes through the medium and the actual propagation speed of the wave in the two media are jointly determined.(3)The mined-out area will have a certain degree of influence on the propagation law of the microseismic signal,which is mainly reflected in: the mined-out area will attenuate the propagation speed of the microseismic signal,and the closer the distance from the source to the monitoring point on the other side of the goaf is,the relative propagation The greater the influence of speed;the HHT principle is used to analyze the signal time-frequency energy,and the influence of the mined-out area on the signal frequency and energy is obtained;the influence of the mined-out area on the source location result is obtained by inversion of the seismic source location Regularity and the main cause of positioning error.This paper has 31 figure,30 table and 72 reference.