# An Experimental Study on the Sealing Mechanism of a Karst Pipeline by Dynamic Water Grouting
## 3 Dynamic Water Sealing Test Study
### Analysis of Velocity of Dynamic Water and Dynamic Water Scour Resistance Effects  
In dynamic water grouting, dynamic water has a large scouring effect on the slurry adsorbed by the magnetic rod. By analyzing the scouring effect of moving water on the slurry, the influence of moving water on the slurry retention rate can be fully understood. Based on the above experimental data, polar analysis was used to determine the influence of the above factors on the two test indexes of velocity of dynamic water and slurry retention rate, and the results are shown in Tables 8 and 9.  
As can be seen in Tables 8 and 9, in a pipe diameter of 50 mm, the velocity of dynamic water and the dynamic water scour resistance effect are most affected by the Fe\({}_{3}\)O\({}_{4}\) misery, followed by the blocking length, and least affected by the water-cement ratio. Figures 13 and 14 show the effects of various factors on the velocity of dynamic water and dynamic water scour resistance.  
\begin{table}
\begin{tabular}{l c c c} \hline
**Factor** & **Water–Cement Ratio** & **Fe\({}_{3}\)O\({}_{4}\) Power Ratio** & **Plugging Length (mm)** \\ \hline K\({}_{1}\) & 35.10 & 23.40 & 20.50 \\ K\({}_{2}\) & 32.90 & 30.50 & 31.00 \\ K\({}_{3}\) & 23.70 & 37.80 & 40.20 \\ k\({}_{1}\) & 11.70 & 7.800 & 6.83 \\ k\({}_{2}\) & 10.96 & 10.17 & 10.33 \\ k\({}_{3}\) & 7.900 & 12.60 & 13.40 \\ Range & 3.80 & 4.80 & 6.57 \\ Primary and secondary factor & Plugging length \(>\) Fe\({}_{3}\)O\({}_{4}\) power ratio \(>\) water–cement ratio \\ \hline \end{tabular}
\end{table}
Table 7: Intuitive water pug pressure analysis table.  
\begin{table}
\begin{tabular}{l c c c} \hline
**Factor** & **Water–Cement Ratio** & **Fe\({}_{3}\)O\({}_{4}\) Power Ratio** & **Plugging Length (mm)** \\ \hline K\({}_{1}\) & 0.521 & 0.540 & 0.484 \\ K\({}_{2}\) & 0.511 & 0.506 & 0.506 \\ K\({}_{3}\) & 0.486 & 0.473 & 0.528 \\ k\({}_{1}\) & 0.174 & 0.180 & 0.161 \\ k\({}_{2}\) & 0.170 & 0.169 & 0.169 \\ k\({}_{3}\) & 0.162 The trends of the factors affecting the flow rate of moving water and the effectiveness of moving water against scouring are as follows:  
1. The velocity of dynamic water and the dynamic water scour resistance effect negatively correlate with the water-cement ratio. The water-cement ratio of the slurry affects its specific gravity, dynamic viscosity, and rheological properties. The smaller the water-cement ratio, the larger the specific gravity and dynamic viscosity of the slurry and the poorer the fluidity, and the sassafras force between the slurry and the pipe wall becomes larger, so it makes the velocity of dynamic water decrease, and the slurry retention rate becomes larger.
2. The velocity of dynamic water and dynamic water scouring resistance is negatively correlated with the amount of Fe\({}_{3}\)O\({}_{4}\). As the amount of Fe\({}_{3}\)O\({}_{4}\) increases, the number of magnetic powder particles wholly wrapped by the base liquid increases, and at the same time, under the effect of magnetic field magnetization, the instantaneous viscosity of the slurry increases and the contact force between the magnetic particles is enhanced, which means that the magnetic rod adsorption of the slurry attached to the body is also gradually increased; it not only enhances the slurry to the resistance of the water but also increases the slurry's dynamic water scouring resistance effect.
3. The velocity of dynamic water and dynamic water scouring resistance effect positively correlate with the blocking length. Due to the increase in blocking length, the magnetic slurry adsorbed by the magnetic rod increases, so the slurry that impedes the water flow increases, the speed of the dynamic water scouring slurry slows down, and the slurry loss rate slows down so that the velocity of dynamic water decreases and the performance of the dynamic water scouring resistance enhances.  
Figure 14: Influence of various factors on the retention rate of the slurry.  
Figure 13: Influence of various factors on the velocity of moving water.