Experimental study of size effects of rock on UCS and point load tests

A number of studies have investigated the size effect of intact rock mostly focusing on the uniaxial compression test. The most widely used being that by Hoek and Brown [1]. The authors have conducted a suite of uniaxial compressive and point load tests on some igneous and metamorphic rocks to assess the effect of size on the results. The results illustrate that the trend of the Hoek and Brown [1] size relationship is not applicable to the tested rock samples particularly at small diameters. It was also found that the size effect relationship differed for the point load and unconfined compressive tests. The authors present the results and provide a discussion as to the potential reasons for the varying size effects at different stress paths. The results have implications for designers when considering potential testing programs and estimations of strength parameters for their designs in rock.