## 4 Discussion
As the _RMR_14 values are higher than _RMR_89, as shown in Table 2 and Equation (15), the difference (_RMR_14-_RMR*_) is greater than that between _RMR_89 and _RMR_* (_RMR_89-_RMR*_), as shown in Figure 4. Figure 4 reveals that for all the cases of weightage, this difference (_RMR_14-_RMR*_) is greatest in the range of 20 to 35 points of _RMR_. In terms of the percentage frequency, their values are 72, 72, 73, 69, and 69 for Cases 1-5, respectively. Based on the correlation Equation (15), _RMR_14 decreases significantly with the stress adjustment factor for all the hypotheses of Table 8. After the application of the stress adjustment factor based on the strength-stress ratio as per the guidelines of Table 8, the percentage frequency of the difference between the stress-adjusted _RMR_14 (_RMR_14*) and _RMR_* is greatest in the range of \(-\)5 to 5 following all the five cases of weightage. Hypothesis 1 of Table 7 for Case 3 is used for the stress adjustment factor for _RMR_14[16]. The leading case in terms of the percentage frequency for the difference between\(RMR_{14}\)* and \(RMR_{14}\) (\(RMR_{14}\)*-\(RMR\)*) in range of \(-5\) to \(5\) is Case 3 with a value of \(58.6\) followed by Cases 1, 2, 4, and 5 with values of \(57.5\), \(56.2\), \(55.6\), and \(51.9\), respectively. Comparing this difference (\(RMR_{14}\)*-\(RMR\)*) with the difference in \(RMR_{89}\) (\(RMR_{89}\)*-\(RMR\)*), the percentage frequency in the range of \(-5\) to \(5\) is lower. These lower values are due to the selection of the stress adjustment factor based on the correlation equation, wherein the data are somewhat scattered from the trend line (\(R^{2}<1.0\)). Secondly, on comparing Figures 3 and 5, the difference in the \(RMR_{14}\) case is more on the negative side as compared to the difference in \(RMR_{89}\), wherein the difference is more on the positive side. According to the Grimstad and Barton [30], massive rocks have a greater probability of the occurrence of rock burst in a high-stress environment and suggest a higher rating for the \(SRF\) in their revised criterion based on relative block size. Their criterion is used for the rock burst occurrence evaluation [31]. In case of a jointed rock mass under high stresses, the \(SRF\) is the function of the strength-stress ratio and relative block size along with the intact rock strength [16; 17]. The effect of the weightage during the determination of the rock-mass quality through back-calculation as per the details of Table 6 along with procedure of Figure 1 and their corresponding effect on the \(SRF\) value using Equation (17) are shown in Figure 6. The line trends in all five cases show that the rate of increase in \(SRF\) with the relative block size increases. In Case 1, the variation of \(SRF\) is \(20.95\) for RQD/Jn from 2 to 12 for all the three ranges of the strength-stress ratio. The Case 1, Figure 6a-c shows that as the strength-stress ratio range changes from 2-3 to 3-4 and then 4-5, the difference between the trend lines for any given value of relative size decreases. These values are \(2.2\), \(1.46\), and \(0.97\), respectively. In all the remaining cases, the differences are controlled by the difference in values of the constant \(\alpha\) in each case and the strength-stress ratio range. In each range of the strength-stress ratio, Cases 2 and 3 have the same difference in \(\alpha\). Similarly, Cases 4 and 5 have the same difference in \(\alpha\). For Cases 2 and 3, the differences in \(\alpha\) are \(0.7\), \(0.45\), and \(0.45\) for the strength-stress ratios 4-5, 3-4, and 2-3, respectively. For Cases 4 and 5, these differences are \(0.8\), \(0.55\), and \(0.55\), respectively. The difference in the trend line in Figure 6a shows that for any values of relative block sizes, the difference between the \(SRF\) for strength-stress ratios 3 and 2 are \(5.81\) for Cases 2 and 3 and \(7.42\) for Cases 4 and 5.