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Xu X.,China University of Mining and Technology | Xu X.,Henan Polytechnic University | Dou L.,China University of Mining and Technology | Lu C.,China University of Mining and Technology | Zhang Y.,Yuejin Coal Mine of Yima Coal Mining Group
Mining Science and Technology | Year: 2010

Blasting and breaking of hard roof are main inducing causes of rock bursts in coal mines with danger of rock burst, and it is important to find out the frequency spectrum distribution laws of these dynamic stress waves and rock burst waves for researching the mechanism of rock burst. In this paper, Fourier transform as a micro-seismic signal conversion method of amplitude-time character to amplitude-frequency character is used to analyze the frequency spectrum characters of micro-seismic signal of blasting, hard roof breaking and rock bursts induced by the dynamic disturbance in order to find out the difference and relativity of different signals. The results indicate that blasting and breaking of hard roof are high frequency signals, and the peak values of dominant frequency of the signals are single. However, the results indicate that the rock bursts induced by the dynamic disturbance are low frequency signals, and there are two obvious peak values in the amplitude-frequency curve witch shows that the signals of rock bursts are superposition of low frequency signals and high frequency signals. The research conclusions prove that dynamic disturbance is necessary condition for rock bursts, and the conclusions provide a new way to research the mechanism of rock bursts. © 2010 China University of Mining and Technology. Source


Xu X.-F.,China University of Mining and Technology | Xu X.-F.,Henan Polytechnic University | Dou L.-M.,China University of Mining and Technology | Liu J.,Yuejin Coal Mine of Yima Coal Mining Group | And 3 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2010

The horizontal stress in the floor of roadway plays an important role in floor burst. According to the theory and characteristics of floor burst, a mechanical model is set up; and the dangerous coefficient of floor burst is also initially given. The research results show that the dangerous coefficient of floor burst is directly proportional to the depth, the horizontal tectonic stress, the square of width of roadway and the coefficient of hard roof abutment pressure, and inversely proportional to the elastic modulus of rock and the square of the thickness of soft rock of floor when the Poisson's ratio is invariable. Through numerical simulation, the distribution laws of horizontal stress rising and vertical stress reducing in the floor are found out. When the stress is more than the breaking point of the floor coal seam, floor burst will happen with the influence of blast firing or roof breaking quickly. According to the research, the intensity weakening theory for floor burst is established. The measure of blasting for stress-relief in the floor is applied to the haulage gateway of 25110 coal face in Yuejin Coal Mine, and has gained good effect. The study conclusions provide theoretical foundation and ways for floor burst prevention in similar conditions. Source

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