ABSTRACT
The uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) of rock is commonly used in civil and mining engineering projects performed in rock environment. However, the test for determining UCS or BTS is time consuming and expensive. On the other hand, it requires well-prepared and high quality core samples. For this reason, some indirect tests such as point load, block punch index test, Schmidt hammer, and ultrasonic velocity tests have been frequently used to predict rock strength for preliminary studies (Broch & Franklin 1972; Gunsallus & Kulhawy 1984; Gaviglio 1989; Sachapazis 1990; Katz et al. 2000; Kahraman 2001; Ulusay et al. 2001; Yasar & Erdogan 2004; Fener et al. 2005; Basu & Kamran 2010; Kohno & Maeda 2012 etc.). However, preparing standard samples for indirect test may not always be possible for weak or soft rocks. On the other hand, we may have only rock fragments to estimate the rock strength in some cases such as drilling. For this reason, developing some models for estimating the rock strength from rock fragments will be useful.
