The effect of specimen size on compressive strength of coal

Abstract This paper describes the results of extensive underground investigations aimed at establishing the in situ strength of coal. Details are given of the equipment and experimental techniques used for testing cubical coal specimens measuring from 0·75 in.–6·6 ft (2 m) in size. Based on over sixty underground test results, an empirical relationship between the strength of coal and the size of the specimens tested is established and its significance for practical applications is outlined.