Numerical analysis of strain energy density at development and longwall face

Strain energy stored within coal mass is one of the main energy sources of coal bursts. Damage caused by a coal burst event can be attributed to the magnitude of strain energy accumulated around excavations. In this study, strain energy density (SED) within coal seam is examined around excavation boundaries during development and longwall retreat. Several numerical models are generated to investigate SED distributions for mining depths ranging between 100 m and 1000 m. For both development and longwall retreat, the maximum SED area migrated deeper into excavation boundaries with increasing mining depth. When the mining depth increased from 100 m to 1000 m, the maximum SED around development increased from approximately 6 kJ/m3 to 780 kJ/m3, while the maximum SED at longwall face increased from approximately 102 kJ/m3 to 1710 kJ/m3. The maximum SED around roadway ribs was lower than that at longwall face at the same mining depth. The sensitivity analyses presented in this study can provide guidance to geotechnical engineers to better understand and evaluate associated risks for different mining conditions.