## 3 Development of a Simulated Grouting Diffusion Experiment Device for Rough Fractures
### Reliability Verification of Grouting Test Device  
The slurry was cement-sodium silicate slurry, the water-cement ratio was 1:1, and the viscosity time-varying equation was \(\mu(t)=0.051+0.0039t^{2.13}\). Before each slurry diffusion test, a water seepage test was carried out to check the tightness of a pipeline connection, and the fracture seepage system was fixed in a horizontal position. Prior to each slurry diffusion test, a water seepage test was conducted to check the sealing of the pipeline connections and ensure the stability of the fracture seepage system in a horizontal position. A flow meter was installed at the outlet of the grouting equipment to provide the real-time monitoring of slurry flow. A pressure control valve was positioned between the nitrogen gas cylinder and the grouting equipment, allowing for the adjustment of grouting pressure as needed for the experiment. After preparing the slurry with a specific water-cement ratio, it was injected through the grouting port into the slurry tank, while simultaneously activating the turbine for slurry agitation. Once the grouting pressure reached the test requirements, the grouting test was initiated, and thereafter, the pressure sensors collected data on the distribution of slurry pressure along the diffusion path. When the slurry achieved a stable flow out of the discharge hole, the current test was concluded, following the specific test plan outlined in Table 1. According to the experimental design, variations in fracture aperture, fracture  
Figure 7: Layout of monitoring equipment. roughness, and grouting pressure were made, and the above test procedures were repeated to complete the remaining slurry diffusion tests. To validate the reliability of this test system, experiments were conducted on slurry flow and diffusion in rough fractured rock. The analysis considered the influence of different grouting pressures (0.2 MPa, 0.4 MPa, 0.6 MPa), fracture apertures (2 mm, 4 mm, 6 mm), and _IRC_ values (5.7, 9.8, 13.6, 17.3) on the spatiotemporal distribution of slurry pressure. Due to space constraints, here we present the test results for a fracture aperture of 2 mm and grouting pressures of 0.2 MPa and 0.6 MPa. The pressure at different measuring points over time under varying grouting pressures is shown in Figure 9a,b. The pressure at the measuring points gradually increases with grouting time and reaches around 90% of the set grouting pressure, indicating a good overall sealing performance of the test system and its suitability for experimental requirements. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Fracture Opening (mm)**} & \multirow{2}{*}{**Fracture Roughness**} & \multicolumn{4}{c}{**State**} \\ \cline{3-6}  & & **0.2 MPa** & **0.4 MPa** & **0.6 MPa** \\ \hline \multirow{4}{*}{2} & 5.7 & & & \\  & 9.8 & \(\surd\) & \(\surd\) & \(\surd\) \\  & 13.6 & & & \\  & 17.3 & & & \\ \hline \multirow{4}{*}{4} & 5.7 & & & \\  & 9.8 & \(\surd\) & \(\surd\) & \(\surd\) \\  & 13.6 & & & \\  & 17.3 & & & \\ \hline \multirow{4}{*}{6} & 5.7 & & & \\  & 9.8 & \(\surd\) & \(\surd\) & \(\surd\) \\ \cline{1-1}  & 13.6 & & & \\ \cline{1-1}  & 17.3 & & & \\ \hline \hline \end{tabular} (Note: “\(\surd\)” means conducted under this condition, used to verify the reliability of the device).  
\end{table} 
Table 1: Parameters of grouting test. Figure 8: Physical diagram of rough fissure grouting system. At grouting pressures of 0.2 MPa and 0.6 MPa, curve charts illustrating the relationship between slurry pressure and diffusion distance were calculated based on the theory of slurry diffusion in rough fractures. Comparative curve charts were then drawn by combining the experimental measured values with the theoretical calculated values. Figure 10 represents the comparative curve chart of the experimental results and theoretical calculations. It is evident that grouting pressure exhibits a nonlinear decrease with increasing diffusion distance, and the experimental values are larger than the theoretical values.