## Materials and Methods
### Characterization and Classification of Rock Mass Based on Rmr14  
After the use of \(RMR_{89}\) for 25 years, an updated version of \(RMR\) known as \(RMR_{14}\) is suggested with a few new parameters, revised rating, and final structure [7]. The structure of \(RMR_{14}\) for determining rock mass quality is represented by Equation (9):  
\[RMR_{14}=(RMR_{b}+F_{0})\cdot F_{s}\cdot F_{e} \tag{9}\]  
where  
\(RMR_{b}=\) Basic \(RMR\) (without the influence of excavation),  
\(F_{0}=\) Adjustment factor similar to \(R_{6}\) in \(RMR_{89}\),  
\(F_{e}=\) Adjustment factor for the excavation method,  
\(F_{s}=\) Adjustment factor for the stress-strain behavior at the tunnel face. The \(RMR_{14}\) structure preserves four parameters with their ratings in the original form as found in \(RMR_{89}\). As per the modification in 2013, these are as follows:  
1. [label=.] 2. Intact rock compressive strength
3. Groundwater condition
4. Orientation of joint with respect to the tunnel axis and excavation direction
5. Joint frequency  
The discontinuity condition was revised in \(RMR_{14}\) by eliminating the joint aperture parameter because of the overshadowing effect. The revised ratings for the remaining four parameters of the discontinuity condition for \(RMR_{14}\) are summarized in Table 2.  
Three new parameters, i.e., intact rock alterability and adjustment parameters \(F_{e}\), and \(F_{s}\), were also introduced in \(RMR_{14}\). The intact rock alterability is rated per results of the slake durability test, as defined in the standard [33]. The rating values of the rock alterability parameter were suggested \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Parameter** & & & & & & \\ \hline \multirow{3}{*}{Persistence} & Value & \(<\)1 m & 1–3 m & 3–10 m & 10–20 m & \(>\)20 m \\  & \(RMR_{89}\) & 6 & 4 & 2 & 1 & 0 \\  & \(RMR_{14}\) & 5 & 4 & 2 & 0 & 0 \\ \hline \multirow{3}{*}{Aperture} & Value & None & \(<\)0.1 mm & 0.1–1.0 mm & 1–5 mm & \(>\)5 mm \\  & \(RMR_{89}\) & 6 & 5 & 4 & 1 & 0 \\  & \(RMR_{14}\) & - & - & - & - & - \\ \hline \multirow{3}{*}{Roughness} & Value & Very rough & rough & \
\begin{tabular}{c} Slightly \\ rough \\ \end{tabular} & smooth & Slicken-sided \\  & \(RMR_{89}\) & 6 & 5 & 3 & 1 & 0 \\  & \(RMR_{14}\) & 5 & 3 & - & 1 & 0 \\ \hline \multirow{3}{*}{Infilling} & Value & None &
\begin{tabular}{c} Hard filling \\ \(<\)5 mm \\ \end{tabular} & \(>\)5 mm & \(<\)5 mm & \(>\)5 mm \\  & \(RMR_{89}\) & 6 & 4 & 2 & 2 & 0 \\  & \(RMR_{14}\) & - & 5 & 2 & 2 & 0 \\ \hline \multirow{3}{*}{Weathering} & Value & Not weathered & Slightly & Moderately & Highly weathered & Decomposed \\  & \(RMR_{89}\) & 6 & 5 & 3 & 1 & 0 \\  & \(RMR_{14}\) & 5 & - & 3 & 1 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison of rating for joint condition in \(RMR_{89}\) and \(RMR_{14}\). in table form in the \(RMR_{14}\) version. The parameter \(F_{e}\), which is a function of \(RMR\) and related to the mechanical excavation method, can be calculated from Equation (10) [7]:  
\[F_{e}=1+2\cdot\left(\frac{RMR}{100}\right)^{2},\ RMR<40; \tag{10a}\] \[F_{e}=1.32-\frac{\sqrt{(RMR-40)}}{25},\ RMR>40. \tag{10b}\]  
where \(RMR=RMR_{89}\). Equation (10) is applicable for mechanical excavation only. When the excavation is performed by the drill and blast method, \(F_{e}=1\). During excavation, \(RMR\) at the tunnel face is considerably lower than predicted during the design phase because of the yielding of the tunnel face and walls. To overcome this effect, an adjustment factor (\(F_{s}\)) is introduced. This factor was defined in terms of Indice de Comportamiento Elastico (_ICE_) (elastic behavior index) by [PERSON] and [PERSON] [34], as expressed in Equation (11). The Kirsch solution for stresses at the perimeter of a circular excavation was used for \(ICE\) determination and has been extended to non-circular tunnels using numerical modelling.