The Redistribution of Stresses Around Longwall Extraction Panels in Bedded Rock Masses

Longwall mining is conducted in bedded rock masses which are not only inhomogeneous but also transversely isotropic. Assuming isotropic rock mass properties can substantially under-estimate the impact longwall extraction can have on the redistribution of horizontal stresses. By invoking the transverse isotropic parameters derived from data on stress-relief roadways it is demonstrated that stress modifications can extend laterally 8 to 10 times the effective excavation height. For longwalls this may mean stress changes could extend up to a 1 km distance. Recognition of the role of transverse isotropy has implications to the understanding of stress concentration effects at the maingate/face corner and also predicting mining conditions in new longwall districts.