How in situ stresses and the driving cycle footage affect the gas outburst risk of driving coal mine roadway

In this paper, numerical simulation models built using FLAC3D were simulated 16 times with different in situ stresses and different driving cycle footages to investigate outburst risk of coal mine roadways. The results suggest that an outburst is most likely to happen when the maximum in situ stress is perpendicular to the roadway axis, and the risk increases to the maximum when the driving cycle footage is at the stress concentration peak. However, conditions are much safer when the maximum in situ stress is parallel to the roadway. The stress distribution was validated with field experiments. The results suggest that most of the roadways in coal mines should be arranged parallel to the maximum stress direction if practical, and that the driving cycle footage should not be at the stress concentration peak. The results will help improve coal mine safe design and provide a driving procedure to prevent gas outbursts. (C) 2012 Elsevier Ltd. All rights reserved.