Abstract
For deep coal mines, geological disturbances or mining activities can cause damage to coal and rock masses, easily inducing dynamic disasters such as rock bursts or coal and gas outbursts, which seriously threaten the safety production of coal mine. In this paper, first, the Liyazhuang Coal Mine introduced the SOS MS (Sensor Observation Service Microseismic) monitoring system from the Polish Research Institute and verified the accuracy of its positioning. Then, to study the characteristics of MS signals induced by different mining activities, based on the field monitoring results, the waveform and frequency spectrum characteristics of MS signals at different energy levels induced by different mining activities are analyzed, and the energy levels of MS signals caused by different mining activities are classified. Studies have shown that there are large differences in the waveform and spectral characteristics of MS signals at different energy levels. High-level energy seismic signals are characterized by large amplitudes, low frequencies, relatively concentrated distribution, long vibration duration, and slow attenuation. In addition, the relationship between mining activities and MS events is also statistically analyzed based on the spatial and temporal distribution of MS events with the advancement of working face, and the results show that the increase of vibration frequency and energy can be precursor information for roof pressure. With the advance of the working face, the MS energy has the characteristic of periodic distribution, which is consistent with the periodic weighting revealed by the working resistance of the support. This study provides a reference for further revealing the energy release mechanism of rock burst.
Highlights
With the increase of mining depth, the occurrence conditions of coal seams are more and more complex. e frequency and damage degree of dynamic disasters such as rock burst and coal and gas outburst are increasing day by day [1,2,3]. us, there is an urgent need to develop new technologies and equipment to monitor coal and rock stability in real time
Based on the realtime monitoring data of MS activities in the deep rock masses during the mining, this study explored the waveform and spectrum characteristics of MS signal generated by different disturbances with different energy levels
DLM-2001 geophone has the function of MS pickup, magnetic transformer signals conversion, signal amplification, etc., of which the sensor is installed vertically on the anchor bolt with a length of 1m or more on the bottom floor to facilitate construction, maintenance, and movement. rough the underground cables, the underground acquired signals will be transmitted to the DLM-SO signals acquisition station, of which the function is to rectify and filter the signals; besides, the DLM-SO acquisition station powers to the geophone
Summary
With the increase of mining depth, the occurrence conditions of coal seams are more and more complex. e frequency and damage degree of dynamic disasters such as rock burst and coal and gas outburst are increasing day by day [1,2,3]. us, there is an urgent need to develop new technologies and equipment to monitor coal and rock stability in real time. Scholars have analyzed the frequency spectrum characteristics of a large number of MS events caused by different mining activities and taken their variation laws as the precursor information to predict the occurrence of rock burst [14,15,16]. Field test results from 8935 working face in Xinzhouyao Coal Mine show that the main frequency spectrum of MS signals before the rock burst is mainly concentrated in 5–60 Hz, and the sharp decrease of the main frequency and the obvious increase of the amplitude of MS signals can be considered as one of the precursors characteristics of rock burst [17]. Based on the realtime monitoring data of MS activities in the deep rock masses during the mining, this study explored the waveform and spectrum characteristics of MS signal generated by different disturbances with different energy levels.
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