Abstract
Monitoring and early-warning are critical for the prevention and controlling of rock burst in deep coal mining. In this study, rock burst risk assessment criterion was built based on the correlativity between seismic velocity and stress state in coal and rock body. Passive seismic velocity tomography using mining-induced seismic waves was conducted regularly and continuously. The evolution of rock burst risk and range in front of a deep longwall panel with folds and adjoining goaf was determined. The influence of pressure-relief measures on rock burst risk was analyzed. The study results indicate that burst risk level and range during panel retreating increase first and then decrease, the peak is reached when it is located at 1# syncline shaft area. When approaching the crossheading, high burst risk zones distribute along the crossheading and further intersect with those in 1# syncline shaft area. Burst risk zones in the inclination of panel show distinct zoning features. Tomography results are in good agreement with the drilling bit result, rock burst occurrence, microseismic activity, and working resistance of hydraulic supports. Pressure-relief measures and mining layout have a distinct influence on burst risk of longwall panel. For prevention and controlling of rock burst risk in deep coal mining, pressure-relief measures should be optimized based on passive tomography results.
Highlights
Due to long-term exploitation, coal resources at shallow depths are gradually exhausted, and mining depth of coal is continually increasing
When the face line is close to the crossheading, high burst risk zones distribute along the crossheading and further intersect with the burst risk zones in 1# syncline area, which indicates the high stress level of the zones adjacent to the crossheading
The main conclusions are as follows: (1) Seismic wave propagation velocity in rock and coal mass is in positive correlation with the stress level
Summary
Due to long-term exploitation, coal resources at shallow depths are gradually exhausted, and mining depth of coal is continually increasing. A new geophysical exploration method inferring the wave propagation velocity through structures, has been a novel measurement method for stress redistribution in underground coal mining. Seismic wave velocity in coal and rock body Regarding seismic sources, this method can be classified into two types, that is, active velocity tomography and passive velocity tomography [16, 17]. Passive seismic velocity tomography can rapidly and continuously present the stress redistribution during coal mining by using mining-induced seismicity as the sources seismic wave [23,24,25,26,27]. Rock burst risk and range of a deep longwall panel with folds and adjoining goaf were determined continuously and visually based on passive seismic velocity tomography. The influence of pressure-relief measures on rock burst risk was analyzed based on tomography results
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