Deformation and support of roadways subjected to abnormal stresses

Abstract

In situ stresses, including both magnitude and orientation, play a major role in the stability of underground coal mine roadways. The orientation of the maximum horizontal stress have a significant impact on roadway stability, especially when roadway is driven perpendicular to the maximum horizontal stress direction. A numerical modeling was carried out to investigate the stress re-distribution around roadway under different horizontal stress orientations. In this study, in situ stress measurement was carried out at Changcun Colliery. There are five parallel trunk roadways servicing the S6 mining district at Changcun Colliery. The result indicated that the orientation of the maximum horizontal stress is perpendicular to the five roadways. To investigate the stress re-distribution around the five roadways group, numerical modeling was carried out using a boundary element code Examine 2D. The influence of horizontal stress direction, pillar size between the roadways, and the excavation sequence of the roadways was examined. A reinforcing system which consists of high strength rock bolts and cables was applied at the five roadways. Both the bolts and cables were installed with high pre-tension forces along the whole length of them. Field observation indicated that this reinforcing system was able effectively restrain the deformation and failure of rock mass surrounding roadways.