# Research on Grouting Pressure of Earth-Rock Dams Reinforced by Polymer Based on Discrete Elements
## 5 Feasibility Verification of the Model  
To evaluate the feasibility of the MatDEM software for numerical simulation, this analysis will verify the stress-strain characteristics of rockfill materials before and after incorporating polymers and the diffusion pattern and range of polymer grout separately:  
1. Stress-strain characteristics: utilizing parameters from an indoor static triaxial test [13] (Table 2), we examined the stress-strain curves of rockfill materials before and after adding polymers under 100 kPa confining pressure, compared the simulation results with the results of indoor tests, and verified the rationality of the model. (Figure 8).  
After the addition of polymer, the deviatoric stress increased with the increase of axial strain and then tended to be stable. At the same time, the addition of polymer changed the shape of the stress-strain curve of rockfill materials. After comparison, the stress-strain curve obtained from the model is more consistent with the change rule of the stress-strain curve of the indoor test, although there is still a part of the error; considering the existence of the error of the numerical model, it can still be a better verification of the reasonableness of the model.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Experimentation** & **Specimen** & **Specimen** & **Coefficient of** & **Coefficient of** & **Axial Strain** \\  & **Height (H/cm)** & **Diameter (D/cm)** & **Uniformity (\(C_{\textbf{u}}\))** & **Curvature (\(C_{\textbf{c}}\))** & **Loading Rate** \\ \hline Indoor static & & & & & \\ triaxial test & 20 & 10 & 21.94 & 2.53 & 0.6 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Parameters of an indoor static triaxial test [13].  
Figure 7: Grouting hole model. (Like Figure 6, the color represents the particle size).  
2. Slurry diffusion form and scope: Because there is no polymer direct grouting rockfill materials test, the simulation was carried out according to the parameters of an indoor polymer grouting transparent soil test [20] (Table 3). The slurry diffusion range and slurry diffusion form obtained by the model were compared with the test results to verify the rationality of fluid-solid coupling (Figures 9 and 10).  
\begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Experimentation** & **Slurry Density (\(\rho_{c}\)/kg\(\cdot\)m\({}^{-3}\))** & **Slurry Viscosity (\(\mu_{c}\)/Pa\(\cdot\)s)** & **Maximum Grouting Pressure (\(F_{\text{m}}\)/MPa)** & **Length of Grouting pipe (\(L\)/mm)** & **Grouting Pipe Inner Diameter (\(d\)/mm)** \\ \hline Indoor polymer grouting test & \(1500\) & \(0.02\) & \(0.8\) & \(6\) & \(4\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Experimental parameters of indoor polymer grouting test [20].  
Figure 8: Comparison of stress–strain curves at 100 kPa: (**a**) before incorporation; (**b**) after incorporation.  
Figure 9: Comparison of slurry diffusion range.  
Through comparison, it can be concluded that the slurry diffusion range simulated by the fluid-solid coupling model is similar to the slurry diffusion range obtained by the test in the X direction and there is a slight difference in the Z direction, but it can still verify its rationality well. Meanwhile, the slurry diffusion pattern obtained from the model simulation is similar to that obtained from the test, both exhibiting a \"U\" shape whose width in the middle expands over time while the lower portion of the slurry spreads outward. This behavior is consistent with the diffusion characteristics of polymer grouting, thereby affirming the accuracy of the numerical simulation method.