# Intelligent Classification of Surrounding Rock of Tunnel Based on 10 Machine Learning Algorithms
## 2 Materials and Methods
### Sample Data Cleaning  
To analyze the sample data outliers, four box diagrams are shown in Figure 6 according to the drilling parameter class and surrounding rock grade.  
\begin{table}
\begin{tabular}{c|c|c|c|c|c} \hline \multicolumn{6}{c}{**The Geological Sketch Record Card of Tunnel Face**} \\ \hline
10 & Degree of structural surface bonding & Good & Fair & Poor & Extremely poor \\ \hline
11 & Integrity & Integrated & Relatively integrated & Relatively broken & Broken & Extremely broken \\ \hline
12 & Groundwater state & None & Drip outflow & Linear outflow & Inrush outflow \\ \hline
13 & The major weak & \multicolumn{3}{c|}{Occurrence} & Angle with tunnel axis \\ \hline
14 & Crustal stress state & \multicolumn{3}{c|}{Low} & High & Extremely high \\ \hline
15 & Surrounding rock grade & I & II & III & IV & V & VI \\ \hline \multicolumn{6}{c}{Tabulator: XXX} & Reviewer: XXX \\ \hline \end{tabular}
\end{table}
Table 2: _Cont._  
\begin{table}
\begin{tabular}{c c c c} \hline
**Surrounding Rock Grade** & **Tunnel** & **Lithology** & **Sample Size** & **Total** \\ \hline \multirow{4}{*}{III} & Luojiashan Tunnel & Dolomite & 110 & \\  & Chufeng Tunnel & Dolomite & 28 & \\  & Xinhua Tunnel & Sandstone & 31 & \\  & Xiangjiawang Tunnel & Limestone & 156 & \\ \hline \multirow{4}{*}{IV} & Gaojiaping Tunnel & Shale/Sandstone & 105 & \\  & Luojiashan Tunnel & Dolomite & 75 & \\  & Chufeng Tunnel & Dolomite & 44 & \\  & Xinhua Tunnel & Sandstone & 125 & \\  & Xiangjiawang Tunnel & Limestone & 30 & \\  & Xiangluping Tunnel & Mudstone/Sandstone & 41 & \\ \hline \multirow{4}{*}{V} & Gaojiaping Tunnel & Shale & 84 & \\  & Luojiashan Tunnel & Dolomite & 62 & \\  & Chufeng Tunnel & Dolomite & 4 & \\  & Xinhua Tunnel & Dolomite & 15 & \\  & Xiangjiawan Tunnel & Limestone & 2 & \\ \hline \multicolumn{6}{c}{Total} & 912 \\ \hline \end{tabular}
\end{table}
Table 3: Intelligent surrounding rock classification sample statistics.  
According to the box diagram method, when the value is not within the interval represented by the following formula Equation (1), it is regarded as an outlier  
\[[\text{Q1}-1.5\times\text{IQR},\text{Q3}+1.5\times\text{IQR}] \tag{1}\]  
where Q1 is the first quartile, namely the equal to the 25 th percentile of all values in the sample from small to large, Q3 is the third quartile, namely the equal to the 75 th percentile of all values in the sample from small to large, IQR is the interquartile range, namely IQR is equal to Q3 minus Q1.  
In Figure 6, under different surrounding rock grades, all four drilling parameters contained outliers. To eliminate the effects of the outliers, the average value of each parameter was used to replace the outlier of each surrounding rock in this study.  
The changes in data characteristics before and after cleaning are compared in Table 4.  
Figure 6: Drilling parameter box diagrams for each surrounding rock grade. (**a**) Penetration velocity (\(V_{p}\), \(\text{m}/\text{min}\)); (**b**) hammer pressure (\(P_{h}\), bar); (**c**) feed pressure (\(P_{p}\), bar); (**d**) rotation pressure (\(P_{r}\), bar).  
In Table 4, after cleaning, under different surrounding rock grades, the distributions of these drilling parameters are more centralized. Specifically, the maximum value is smaller, the minimum value is larger, and the standard deviation is smaller.