## 4 Field Scale Test  
In order to study the feasibility of tunnel anchoring schemes in sandstone formations, field-scaled tunnel anchoring test was designed. Field scale testing allows for large-scale structures of testing equipment and material models, without indoor site limitations, reducing costs, simplifying model production and disassembly, and saving material costs.  
\begin{table}
\begin{tabular}{c c c c} \hline \multirow{2}{*}{**Rock Character**} & \multirow{2}{*}{**Weathering Degree**} & \multicolumn{3}{c}{**The Peak Shear Strength**} \\ \cline{3-4}  & & **F\({}^{\prime}\)** & **C\({}^{\prime}\) (MPa)** \\ \hline K\({}_{2}\)l\({}^{2}\) Conglomerate & Medium & 1.11 & 0.88 \\ K\({}_{2}\)l\({}^{2}\) Sandstone & Slightly & 0.63 & 0.38 \\ K\({}_{2}\)l\({}^{2}\) Conglomerate & Slightly & 1.42 & 0.99 \\ K\({}_{2}\)l\({}^{1}\) Conglomerate & Slightly & 1.65 & 1.25 \\ \hline \end{tabular}
\end{table}
Table 6: Rock mass direct shear test.  
\begin{table}
\begin{tabular}{c c c c} \hline \multirow{2}{*}{**Rock Character**} & \multirow{2}{*}{**Weathering Degree**} & \multicolumn{3}{c}{**The Peak Shear Strength**} \\ \cline{3-4}  & & **F\({}^{\prime}\)** & **C\({}^{\prime}\)/MPa** \\ \hline K\({}_{2}\)l\({}^{2}\) Conglomerate & Slightly & 1.42 & 0.95 \\ K\({}_{2}\)l\({}^{1}\) Conglomerate & Slightly & 1.69 & 1.15 \\ K\({}_{2}\)l\({}^{1}\) Conglomerate & Slightly & 1.58 & 0.91 \\ \hline \end{tabular}
\end{table}
Table 7: Direct shear test on the contact surface between rock mass and concrete.  
\begin{table}
\begin{tabular}{c c c c} \hline \multirow{2}{*}{**Rock Character**} & \multirow{2}{*}{**Weathering Degree**} & \multicolumn{3}{c}{**The Peak Shear Strength**} \\ \cline{3-4}  & & **F\({}^{\prime}\)** & **C\({}^{\prime}\)/MPa** \\ \hline K\({}_{2}\)l\({}^{1}\) Conglomerate & Slightly & 621.0 & 1.2 \\ \hline \end{tabular}
\end{table}
Table 8: Concrete pull-out test.  
The efficiency of on-site scaling tests has been improved. Due to the smaller size and lower load requirements of scaled models compared to real components, the testing process can be accelerated, and the testing period can be shortened. The more consistent the rock type selected for the anti-pull test of tunnel anchorages is with the actual rock type, the closer the obtained load strain characteristics, anti-pull capacity, and anti-pull mechanism of tunnel anchorages are to reality. The open site facilitates the entry and exit of large equipment, and larger scale models can be selected to reduce the impact of size effects. And the on-site testing is highly targeted, taking into account the actual site conditions and environment, such as temperature, humidity, lighting, etc., to eliminate external factors. At the same time, the terrain can be fully utilized to make the scaled model more realistic in terms of terrain similarity, and the load size, loading rate, boundary conditions, and other influences can be accurately controlled on site. The scale test made on site can successfully describe the test results that are consistent with the actual situation. This article conducted on-site scaled model experiments, considering the construction conditions, site size limitations, and budget. The scale used for this model experiment was 1:12.