Geological and Geotechnical Influences on the Caveability and Drawability of Top Coal in Longwalls

Longwall Top Coal Caving (LTCC) is a means of efficiently mining thick (>4.5m) coal seams and is an established technology in China with more than 20 years experience and over 100 faces in operation in a variety of different mining conditions. A CSIRO – ACARP funded project has utilised the database of experience gathered by the Chinese to develop a LTCC caving assessment procedure for evaluating Australian coal seams based on numerical modelling. The CSIRO developed continuum code COSFLOW has been used to asses LTCC mining at multiple scales. COSFLOW analyses the global stress redistribution from the ground surface to below the mining seam examining the influence of geology and the geotechnical properties of the rock mass and allows for an initial assessment of LTCC based on mining depth, coal strength and seam thickness early in the development of a thick seam mining project.