Scaling Compressive Strength from Mini-cylinder Specimens of Sub-bituminous Coal

This paper presents the results of laboratory tests conducted on a series of mini-cylinder specimens to measure the uniaxial compressive strength of sub-bituminous coal, which is sparsely recorded in the public domain. The measurements were made on mini-cylinder specimens (non-standard) sized from 9.3 to 22.6 mm in diameter, sourced from the Surat–Clarence–Moreton Basin in Australia, an important region for coal mining and coal seam gas extraction. The tested specimens presented poorly developed cleats and were texturally classified as non to poorly banded, although the composition is rich in vitrinite group macerals. The inherent variability of experimental coal strength results was found to be related to fabric and texture. The results from the mini-cylinder specimens could be scaled to predict the behaviour of larger core sizes commonly used for testing mechanical variability and for estimating full seam rock mass strength.