“…According to the factors that the rock with the lower peak strain has a higher brittleness, the order about rock brittleness of the 5 samples from high to low is 96H-113-H, 21-T-1, 21-H, 113H-83-H, 21-T-2. On the basis of the previous brittleness index studies, we calculate the 6 different brittleness indicators. As is shown in Table 1, B1 (Rickman et al 2008) and B2 (Guo et al 2015) are proposed according to Young's modulus (E) and Poisson's ratio (υ), B3 (Altindag, 2010) is a brittleness indicator which consider the post-peak stress state, and B4, B5 (Tarasov and Potvin, 2013) and B6 (Xia et al 2016) consider both pre-peak and post-peak state of the complete stress-strain curves. It is shown in Figure 2 that B2 of the 5 samples is consistent with the conclusions from the figure 1.…”