Rock variability and establishing confining pressure levels for triaxial tests on rocks

Selection of site-specific regression model for characterization of uniaxial compressive strength of rock

“…Geotechnical properties have been modelled in the literature to follow one type of distribution or the other (e.g., [53][54][55][56][57]). For example, UCS has been modelled to follow distributions like normal and lognormal in the literature [58,59]. Normal distribution is used in this study to model UCS because of its successful applications in the literature and its mathematical convenience.…”

Variability of unconfined compressive strength in relation to number of test samples

“…ASTM method E 122 (1989) and Gill et al (2005) state that strength data should be normally distributed to carry out statistical procedures. Although previous research suggests that unconfined compressive strength data tend to follow a normal distribution (Gill, 1963;Yamaguchi, 1970;Hsu and Nelson, 2002;Sari and Karpuz, 2006), Q-Q (quantile-quantile) probability plots were used to assess the normality of unconfined compressive strength data for each rock type. The Q-Q plot graphically compares the quantiles of a variable's distribution with the quantiles of the normal distribution.…”

Microfracture of stones under compressive conditions

“…Therefore, the failure and damage mechanisms of stone at different stress levels should be determined by performing triaxial tests. The friction angle and cohesion have been widely used for design purposes [2]. Friction resists the sliding on the surfaces of closed cracks, indirectly influencing the non-linear deformation caused by the fracture of rock [3].…”