The Limitations of the Observational Method for Roof Support and Subsidence Management in High Production Longwalls

Monitoring is an essential component of the observational method but it is not a substitute for geotechnical design. Roof extensometry is used extensively for managing ground control. It provides an additional and essential level of control for the management of safety but it should not be relied on to provide the necessary warning of interruptions to longwall extraction. Longwall extraction does not have the flexibility to allow for the modifications that are an essential part of the observational method. A more conservative initial design for ground control is required. A logical framework for such design is presented.