The roof fall probability is described by the probability of the rock fall between the shield and the coalface, from which the roof collapses into the working area and can become a danger for the employees. The maximum possible shield height compared to the actual one is another factor for increasing safety in the longwall mining area. If the longwall got higher than the maximum possible shield height as the result of roof falls in front of the canopy, the crushed rock hits the canopy with high kinetic energy. The steel structure can be destroyed or the legs can be overloaded and damaged by sudden pressure. For this reason, a gap between the canopy and the roof must be eliminated and the canopies must be loaded with sufficient pressure.
Dipl.-Ing. Ulrich Langosch
DMT GmbH & Co. KG
Civil & Mining Engineering
Am TÜV 1, 44307 Essen, Germany
Tel +49 201 172-1302 / Fax +49 201 172-1012