Abstract
Uniaxial Compressive Strength (UCS) and Indirect Tensile Strength Index (ITS) are two of the most important geomechanical properties of rocks, which are used for designing rock slopes, excavations and tunneling. These parameters also have wide application in the mining industry since they are used in rock mass classification of roof, floor and pillars of coal mines to select the most economical mining method and mining geometry. Standard test methods for determination of UCS and ITS have been presented by prominent organizations such as ASTM and ISRM. However, the mentioned test methods for evaluation of UCS and ITS are tedious, time consuming and expensive, in contrary to the Point Load – Axial (PLA) and - Diametral (PLD) test methods, which are simpler and run quickly. Since the loading and the failure mechanism of UCS and ITS tests are similar to PLA and PLD, respectively, the correlations between these pairs are anticipated. The main objective of this study is to identify the relationship between the unconfined compressive strength and the axial point load test as well as the relationship between the indirect tensile strength and the diametral point load for the shale, clay stone and limestone roof rocks in the Illinois Coal Basin. The studied data are the results of rock mechanics tests performed on the roof rock core samples of a coal mine in Illinois, as it is established by the ASTM. The results indicate that there is a correlation between UCS and PLA, as well as ITS and PLD.
