Document Type

Conference Paper

Publication Date


Publication Details

Terry Medhurst, Rudd Rankine and Michael Kelly, 14th Coal Operators' Conference, University of Wollongong, The Australasian Institute of Mining and Metallurgy & Mine Managers Association of Australia, 2014, 42-50.


Prediction and assessment of caveability for Longwall Top Coal Caving (LTCC) operations remains problematic. Whilst operating effectively in China for some years and having recently been introduced into Australia, there remains limited information and methods for predicting optimal coal recovery and productivity under Australian conditions. This paper describes the development of a novel approach to LTCC assessment. This involved the development of a coal failure and breakage model and then simulation of the LTCC process using a hybrid FLAC/PFC model. In order to establish key parameters for coal fracture, a Synthetic Rock Mass (SRM) modelling process was used to examine a range of variables such as particle size, clumping logic, contact strength, and fracture energy and how they relate to the strength, stiffness and dilation behaviour of the coal. This was processed was calibrated using triaxial test data. Simulation of the LTCC process used a Particle Flow Code (PFC) model of coal behaviour based on the SRM results embedded within a FLAC model to allow simulation of both far field and near field effects. This allows the influence of depth, mining induced stresses, goaf behaviour, weak and strong overlying strata, to be superimposed on the near field caving response. The main outputs from this modelling process include a measure of caveability or recovery and draw profile; and the effect of operating controls upon them.