Abstract
Microseismic events commonly occur during the excavation of long wall panels and often cause rock-burst accidents when the roadway is influenced by dynamic loads. In this paper, the Fast Lagrangian Analysis of Continua in 3-Dimensions (FLAC3D) software is used to study the deformation and rock-burst potential of roadways under different dynamic and static loads. The results show that the larger the dynamic load is, the greater the increase in the deformation of the roadway under the same static loading conditions. A roadway under a high static load is more susceptible to deformation and instability when affected by dynamic loads. Under different static loading conditions, the dynamic responses of the roadway abutment stress distribution are different. When the roadway is shallow buried and the dynamic load is small, the stress and elastic energy density of the coal body in the area of the peak abutment stress after the dynamic load are greater than the static calculations. The dynamic load provides energy storage for the coal body in the area of the peak abutment stress. When the roadway is deep, a small dynamic load can still cause the stress in the coal body and the elastic energy density to decrease in the area of the peak abutment stress, and a rock-burst is more likely to occur in a deep mine roadway with a combination of a high static load and a weak dynamic load. When the dynamic load is large, the peak abutment stress decreases greatly after the dynamic loading, and under the same dynamic loading conditions, the greater the depth the roadway is, the greater the elastic energy released by the dynamic load. Control measures are discussed for different dynamic and static load sources of rock-burst accidents. The results provide a reference for the control of rock-burst disasters under dynamic loads.
Highlights
The sudden release of the elastic energy accumulated in an ore body around a mining working is likely to induce a rock-burst accident [1]
When vibration waves caused by roof breakage, fault slip, blasting and other mining activities affect the coal and rock mass near the mining working, the vibration waves cause the additional dynamic loads in the coal and rock mass; in severe cases, the sudden instability of the coal and rock mass will lead to a rock-burst accident [12,13,14]
When the dynamic load peak particle velocity (PPV) are 0.6 m/s, 1.0 m/s and 1.4 m/s, the stress values after the dynamic load are 11.0 MPa, 8.02 MPa and 6.77 MPa, respectively, the energy densities are 145.4 kJ/m3, 56.9 kJ/m3 and 38.6 kJ/m3, respectively, and the peak stress and elastic energy density are less than those in the static calculation. These results show that the dynamic load causes the coal body to be damaged in the area of the peak abutment stress; that the larger the dynamic load is, the greater the coal body damage is; and that the dynamic load induces a sudden release of elastic energy in the stress concentration area, which can cause a rock-burst accident
Summary
The sudden release of the elastic energy accumulated in an ore body around a mining working is likely to induce a rock-burst accident [1]. The source of energy for static loading rock-burst accidents is the stress concentration near the mining workings. When vibration waves caused by roof breakage, fault slip, blasting and other mining activities affect the coal and rock mass near the mining working, the vibration waves cause the additional dynamic loads in the coal and rock mass; in severe cases, the sudden instability of the coal and rock mass will lead to a rock-burst accident [12,13,14]. Numerous field measurements have shown that a high dynamic load will cause a more severe rock-burst accident and greater damage to the rock surrounding the roadway [15,16]
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