## 3 Tests Results and Analyses  
### Grout Propagation Process  
Sixteen groups of experiments were carried out at room temperature (22 degrees), and the whole process of grout diffusion was recorded. Five sets of test images were selected as the representatives for the analysis. Figure 8a presents the grout diffusion process for the condition \(JRC\) = 2-4. In this case, the fluctuation of the simulated rough fracture was smaller. The diffusion process could be divided into two stages: Near circular diffusion and the whole passage near rectangular stage. The first stage lasted for 100 s, and the same slurry diffusion distance was formed in each direction. The next stage was sustained from 100 to 280 s, after grouting for 100 s, the grout began to spread to the boundary. Afterwards, in the direction of the X axis, with the scouring effect of water flow, the velocity of grout diffusion in the direction of flow became faster than that in the direction of the reverse flow. In the direction of the Y axis, the diffusion distance was basically the same in the direction of the vertical flow. Figure 8b shows pictures of the grout diffusion in trial No.6, where the grout diffusion was similar to that in trial No.3. The gel time was the shortest as a result of the grout solidifying quickly. At 120 s, a water gushing channel was formed under the irnush of water. A compete grout diffusion process was reached with continuous grouting. Figure 8c presents pictures showing the fair effect of water plugging. The grout was washed away easily since the rate of the initial water flow was the fastest, and the grout was taken away by water to the outlet. The grout also did not spread to the boundary.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Level**} & \multirow{2}{*}{\begin{tabular}{c} **The Roughness of** \\ **Fracture (JRC)**_A_** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Initial Water Flow** \\ **Rate (cm/s)**_B_ \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Gel Time (s)**_C_ \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Fracture Opening** \\ **(mm)**_D_ \\ \end{tabular} } \\ \hline
1 & 2–4 (\(A1\)) & 0.4 (\(B1\)) & 36.5 (C1) & 2 (\(D1\)) \\
2 & 6–8 (\(A2\)) & 0.8 (\(B2\)) & 46.7 (C2) & 3 (\(D2\)) \\
3 & 12–14 (\(A3\)) & 1.2 (\(B3\)) & 60.2 (C3) & 4 (\(D3\)) \\
4 & 18–20 (\(A4\)) & 1.6 (\(B4\)) & 83.6 (C4) & 5 (\(D4\)) \\ \hline \hline \end{tabular}
\end{table}
Table 1: The four factors and four levels used in the experiment.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Trial No.**} & \multirow{2}{*}{\begin{tabular}{c} **Symbol for** \\ **Trial** \\ \end{tabular} } & \multicolumn{4}{c}{**Factors and Levels**} \\ \cline{3-6}  & & \begin{tabular}{c} **Initial** \\ **The Roughness of** \\ **Fracture (JRC)**_A_ \\ \end{tabular} & \begin{tabular}{c} **Initial Water** \\ **Flow Rate** \\ **(cm/s)**_B_ \\ \end{tabular} & \
\begin{tabular}{c} **Fracture** \\ **Gel Time (s)**_C_ \\ \end{tabular} &
\begin{tabular}{c} **Opening (mm)** \\ **D_ \\ \end{tabular} \\ \hline
1 & \(A1B1C1D1\) & 2–4 & 0.4 & 36.5 & 2 \\
2 & \(A1B2C2D2\) & 2–4 & 0.8 & 46.7 & 3 \\
3 & \(A1B3C3D3\) & 2–4 & 1.2 & 60.2 & 4 \\
4 & \(A1B4C4D4\) & 2–4 & 1.6 & 83.6 & 5 \\
5 & \(  
Figure 8d shows images of the grout diffusion in test No.13 with simulation of a rough fracture of _JRC_ = 18-20. The maximum fluctuation degree increased the resistance of grout diffusion. The grout spread along the direction of the Y axis first. Then, it began to expand across the rough fracture with the increase of grouting pressure and finally reached the boundary of the model. Figure 8e presents the grout diffusion in trial No.14, which had the best sealing effect in orthogonal experiment, and the whole fracture was filled with grout. The process of grout diffusion was similar to that trial No.13.