Analysis of impact of sensor installation method on quality of microseismic signals in roadways
Microseismic monitoring technology is a new monitoring technology developed on the basis of acoustic emission and seismolo-gy.It mainly studies the impact on production activities through observation and analysis of microseismic events.At present,there are many installation methods for microseismic sensors,but each has its own advantages and disadvantages,and suitable installation methods need to be proposed for different roadway environments.Two methods were used to install microseismic sensors in the No.230108 work-ing face of Xinji No.2 Coal Mine,namely the rigid connection installation of fully anchored anchor rods and the installation of drilling grouting adhesive rock walls.A week long microseismic test was conducted,and a total of 553 microseismic events were collected.By analyzing the frequency domain characteristics of microseismic events,it was found that the frequency components below 400 Hz in channel 1(installation of fully anchored anchor rods)signal mostly accounted for 45％to 75％of the total frequency domain compo-nents,with an average proportion of 60％.The low-frequency and high-frequency components of channel 1 signal were relatively rich.The frequency components below 400 Hz in channel 2(installation of drilling)signal accounted for over 80％of the total frequency do-main components,indicating a loss of high-frequency components.The signal energy collected by channel 1 was greater than that of channel 2,with an average true energy value of approximately 7.24 times that of channel 2.The signal-to-noise ratio value of the signal collected by the sensor installed with anchor rods ranged from 20 to 50 dB,with an average value of 27 dB.The signal-to-noise ratio val-ue of the signal received by the sensor installed with drilling method was mostly between 5 to 35 dB,and some even negative,with an average value of 17 dB.The signal-to-noise ratio of channel 1 was 1.6 times that of channel 2.The signals obtained from sensors in-stalled with anchor rods had the characteristics of rich frequency domain and high signal-to-noise ratio.The signal quality was higher compared to drilling installation.
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