Research on multiparameter monitoring of microseismic signals of coal and rock rupture in tunnel excavation
In order to reveal the law of mine earthquake occurrence"pre-middle-post"the dynamic phenomenon of coal rock in the process of roadway excavation in deep mine.The microseismic monitoring technology is used to conduct real-time monitoring of microseismic events caused by operation disturbance and ground stress changes in the background of the excavation process of Wuyang Coal Mine in Lu'an.And through Fast Fourier Transform(FFT),Wavelet Packet Transform,and S-transform,to analyze the time series,spectrum,and energy of microseismic signals during the operation process,and a multi parameter monitoring model for microseismic signals is constructed.The following conclusion is drawn:(1)During the monitoring period,the daily cumulative frequency and rate of change of microseismic events have a trend of first increasing and then decreasing.The maximum daily cumulative frequency and rate of change occur on the day of the main earthquake;(2)The amplitude and energy of microseismic signals for general events,precursor events and aftershock events are lower than those of the main shock event,but their duration is 2～4 times that of the main shock signal.When the main shock event occurs,the amplitude of microseismic events reaches its peak,and the frequency domain of the signal moves towards the low-frequency band;(3)The overall energy of wavelet packets for 4 types of microseismic events shows a decreasing trend,with the 1st and 16th frequency bands corresponding to maximum and minimum points,respectively.The frequency band energy of wavelet packets is mainly in the 1～3 frequency bands,and the percentage of energy in the 16 frequency band of the main seismic signal is still at a high point,indicating that there is still residual microseismic energy in the later stage of the main seismic event,and the working face will not immediately enter the safety period;(4)A micro seismic multi parameter analysis method was proposed,and a 4 × 4 micro seismic multi parameter monitoring model was constructed with time series S,time domain T,frequency domain F,and wavelet packet frequency band energy E as parameters.It can improve the accuracy and reliability of microseismic monitoring.The research results can provide technical support for the prediction and early warning of coal and rock dynamic disasters in mines,and provide theoretical basis for early sensing of microseismic activity and timely response to preventive measures in this type of mine.
Coal rock powerSpectrumWavelet packet transformS transformMulti parameter monitoring
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