## 3 Modification of the _RMR_ and \(Q\) Systems Since Their Establishment
### Modification in Terms of Characterization
#### 3.1.1 Rmr  
System  
After its development, the _RMR_ system has established many applications in several engineering projects, like tunnels, foundations, mines and slopes but utmost applications are in the field of tunneling [57]. This classification system was continuously refined [8; 21; 22; 43; 44; 45; 23] as more case records became available to approve it with global standard, as summarized in Table 2. In 1974, [PERSON] revised the system and presented its first alterations: weathering, aperture and persistence of jointswere united within the term \"discontinuity condition\" with variations to the relative points [21]. Thus, the eight parameters creating the system was reduced to six. This revised \(RMR\) was again modified for intact rock strength (\(\sigma_{c}\)) and negative values were applied as adjustment parameters for the first time in 1975 [43]. The rating range for the first-class rock-mass (90-100) was changed to 81-100. The joint roughness was added as an additional parameter to the system and as a result, the assessment score was increased for the parameter \"condition of joints.\" In 1979, modifications associated to the joint spacing, joint condition and ground water were made [44]. Main alterations to the \(RMR\) system were suggested in 1989 [22]. These comprised new graphs and tables for the score of \(\sigma_{c}\), \(RQD\), spacing and situation of discontinuities. The refined system is called \(RMR_{89}\). In \(RMR_{89}\), the basic \(RMR\) (\(RMR_{\text{b}}\)) score is the sum of the scores of five stated parameters. It comprises the score for \(\sigma_{c}\) (\(R_{1}\)), \(RQD\) (\(R_{2}\)), joint spacing (\(R_{3}\)), joint condition (\(R_{4}\)) and groundwater condition (\(R_{5}\)). The \(RMR_{89}\) system is the outcome once adjusting \(RMR_{\text{b}}\) for joint direction with respect to the tunnel alignment and direction of excavation score (\(R_{6}\)). The corresponding quality is achieved using Equation (2). \[RMR_{89}=R_{1}+R_{2}+R_{3}+R_{4}+R_{5}+R_{6} \tag{2}\]  
The minimum values of \(R_{2}\) and \(R_{3}\) for \(RMR_{73}\) version of \(RMR\) are 3 and 5 respectively, as listed in Table 2. A continuous-rating idea through equations was presented by [PERSON] and [PERSON] for \(R_{2}\) and \(R_{3}\) values of \(RMR_{73}\) system. According to \(RMR_{89}\), the \(R_{2}\) and \(R_{3}\) values are from 0 to 20, after modification [45] (as shown in Table 2). The continuous-rating concept through equations, which was introduced by [PERSON] and [PERSON] for \(RMR_{73}\), was extended for \(RMR_{89}\) to characterize \(R_{2}\) and \(R_{3}\) easily and precisely [58]. Since its development [59], \(RQD\) was used in \(RMR\) and \(Q\) system because of its historical background. Because of some intrinsic limitations and ignoring the basic definition [60; 61; 62], \(RQD\), along with joints spacing, is substituted by joint frequency in the excavation face or rock core [46]. [PERSON] [63] analyzed the arguments about the different definitions of \(RQD\) in different parts of the world and the use of rock exposures for determining \(RQD\) which are considered as the main sources of error. In fact, these are modifications made in the \(RQD\) for intended purposes and adopted wrongly. However, it cannot be considered as a system fault and is not sufficient reason to abandon the use of \(RQD\) in classification systems. The modified criterion shows that \(RMR_{89}\) can be stated in terms of five parameters and calculated using Equation (3):  
\[RMR_{89}=R_{1}+R_{2-3}+R_{4}+R_{5}+R_{6} \tag{3}\]  
where \(R_{2-3}\) shows the rating for joint frequency. After 25 years of use, an updated version of \(RMR_{89}\), known as \(RMR_{14}\), was proposed with new parameters, a revised rating and final structure [23]. The structure of \(RMR\) in \(RMR_{14}\) version is represented by Equation (4).