The change of rockmass stress and stress tensor rotation during longwall mining exploitation

Mining and geomechanical conditions during mining operation in underground mine are still changing. The changes depend on many factors, as e.g.: the buried depth, type of rocks, geomechanical parameters of rocks, the type of exploitation system or the layout of mining in space. The paper presents the results of underground monitoring and numerical analyses of the state of stress in a rock mass during longwall panel advance in a coal underground mine. The in situ stress measurements were conducted with the help of biaxial stress-meters with vibrating wires.3D numerical modeling has been also carried out to perform a rock mass behavior during longwall mining operation. The study shows not only considerable changes in stress values, but its direction rotation as well. The knowledge about the stress regime and its possible change can help in support system design for gates and improve the staff safety.