Self-shocking microseismic monitoring technology and its application in prediction of dynamic pressure in shallow coal seam

Microseismic monitoring technology is widely used in the coal mine safety and coal-rock dynamic disasters prediction.Source location is the basis of application of microseismic monitoring technology to study the fracture mechanism of coal and rock mass, analyze the law of mine activity and forecast the coal and rock dynamic disasters.In order to improve the source location accuracy of the microseismic monitoring system, a self-shocking microseismic monitoring technique was proposed.In this technique, a self-excited source was used to transmit the vibration signals which were used to inverse the wave velocity field of the monitoring area, and the inversed wave velocity field was applied to calculate the location of the microseismic source. Based on this technology, a coal mine microseismic monitoring system named KJ768 was developed.Both the fixed point blasting underground and comparison test of similar monitoring system were adopted to monitor the positioning accuracy of the KJ768 microseismic monitoring system, and the results shown that under a certain detector net and space arrangement its positioning accuracy could reach less than 10 m.The developed KJ768 coal mine microseismic monitoring system was applied to predict dynamic mining pressures in shallow coal seam.After the experimental study on the relationship between the results of the microseismic monitoring andthe working face pressure observation, the numbers and total energy of microseismic events were selected as the period indexes of the cycle pressure and dynamic mining pressure, and the warning threshold were also determined. Finally, three times of dynamic mining pressure and nearly 20 times of cycle pressure were accurately predicted, which had provided a scientific basis and effective guidance for the prevention and control of abnormal mining pressures.