The Study On Propagation Laws Of Rock Rupture Microseismic Signal Through The Goaf

The characteristics and regularity of microseismic signal are essential in microseismic monitoring.The existence of mined out area nevitably influences microseismic signals.Therefore,the study on regularity of microseismic signal propagation in goaf should be cause for concern.A considerable amount of theoretical and experimental research on microseismic signal propagation was done by the domestic and foreign experts.However,there were few researches on microseismic signal propagation after passing through the goaf.Based on the different locations,the rockburst source was classified in this paper.Then the position of microseismic sensor was expounded and the goaf was classified in detail.It's lay a foundation for the numerical simulation and experimental study by indicating the relative relationship among the goaf,the rockburst source and seismic sensor.During the study of seismic wave propagation in coal and rock,the edge of the mined out area was considered as a free surface,and the propagation of the seismic wave propagation to the goaf was analyzed theoretically.Finally,the characteristics of microseismic signal through the goaf were studied by numerical simulation and experimental study.These conclusions were obtained: when the microseismic signal through the weak rock zone,energy,amplitude and speed of transmission would be reduced,but the degree of reduction was disproportional to the strength of weak rocks;The energy,amplitude and velocity of the signal were greatly attenuated while microseismic signal through the goaf,and the larger the mined out area,the greater the degree of attenuation;The influence of the width of the goaf on the signal propagation was greater than the height of the goaf;Microseismic signal show low frequency propagation characteristics,and spectrum shift to lower frequency obviously while microseismic signal go through the weak rock and the goaf;During the period of roof breaking the main shock was more obvious than foreshock,and lasted for a longer time;In terms of the spectrum,the main shock spectrum was more abundant than the foreshock.In addition,no matter foreshock or main shock,compared the spectrum of the signal on the plate with the spectrum of the signal on the roof,the extremum value of frequency was reduced and the spectrum of signal was shifted to lower frequency.