Point Load Test on Meta-Sedimentary Rocks and Correlation to UCS and BTS

Excerpt

The point load test has been considered as a cheap and useful testing method to estimate the strengths of rocks due to its ease of testing, simplicity of specimen preparation, and possible field application (Broch and Franklin 1972; Bieniawski 1975; Kahraman and Gunaydin 2009; Basu and Kamran 2010). It has been often reported as an indirect measure of the compressive or tensile strength of rocks (Fener et al. 2005; Çobanoğlu and Çelik 2008; Heidari et al. 2012; Chau and Wong 1996). Samples can be of various shapes, including cut cylindrical cores tested axially or diametrically, cut blocks, or irregular lumps [Brook 1985; International Society for Rock Mechanics (ISRM) 1985; American Society for Testing and Materials (ASTM) 2008]. The point load test can be used to test both strong and weak rocks (Hardy 1997; Heidari et al. 2012; Tsiambaos and Sabatakakis 2004; Kahraman and Gunaydin 2009). Establishing a proper correlation between the uniaxial compressive strength (UCS) and point load strength index (I _s(50)) is one of the most critical concerns in applying the point load test on various rock types. However, numerous experimental studies have shown that the conversion factors may vary with rock types and rock classes (igneous, metamorphic, and sedimentary rocks) (Tsiambaos and Sabatakakis 2004; Fener et al. 2005; Kahraman and Gunaydin 2009; Kahraman et al. 2005). Research is still actively on-going for certain rocks at some specific locations (Heidari et al. 2012; Singh et al. 2012). The relationship between the Brazilian tensile strength (BTS) and I _s(50) is also often considered and assessed (Heidari et al. 2012). …