## 3 Tests Results and Analyses
### Analysis of the Change in the Water Flow Rate during the Grouting  
Grout and water flowed out through the outlet to the weighing platform during the grouting and flowing water rate changed constantly. The change in the water flow rate was monitored at all times by using a camera. The flow change was expressed by the variation in the platform scale number. The change curve of the flowing water rate in the orthogonal experiment can be divided into three categories: \"Single platform decreasing type\", \"double platform decreasing type\", and \"multi-peak fluctuating type\". The change curve of the flowing water is shown in Figure 10.  
(1) \"Single platform decreasing type\" change curve of the water flow rate  
The single platform decreasing type was split into three stages, as shown in Figure 10a. The first stage was the initial rising stage, which indicated the start of grouting. The flow rate rose to the peak value as the grout began to enter the fracture. The reason for this is that the grout washed the original water in the fracture away and caused the water flow rate to reach its peak value. The second stage was the stable platform stage. As grouting continued, chemical grout was injected into the fracture constantly, and the common movement of two kinds of fluid with chemical grout and flowing water was maintained. The flow of water at the end of the fracture was kept steady. In the third stage, the flow declined rapidly and eventually became steady. The chemical grout gradually spread to the edge of the fracture until it filled the fracture and caused concretion. An effective barrier to flowing water flow was realized, which caused the flow to decline and become steady.  
(2) \"Double platform decreasing type\" change curve of the water flow rate  
The \"double platform decreasing type\" change curve of the water flow rate is shown in Figure 10b. It can be divided into three stages. In the first stage, from 0 to 275 s, the grout diffused slowly because of the large fluctuation (_JRC_ of 18-20). The grout primarily spread into the grooves and had little effect on the water flow rate. After the grout had filled the grooves in the direction of the \(Y\) axis, the grout spread all the around and the water flow rate declined rapidly. In the second stage, from 275 to 350 s, the chemical grout was injected into the fracture and a stable grouting stage formed. After 350 s, the water flow rate reduced obviously while the grout filled the fracture. The final change in the water flow rate was close to 0 and a good water plugging efficiency was achieved.  
Figure 9: The types of seepage pressure change curves. (**a**) “Single peak type” of seepage pressure. (**b**) “Multi-peak type” of seepage pressure. (**c**) “Multi-peak type” of seepage pressure. (**d**) “Platform type” of seepage pressure.  
(3) \"Multi-peak fluctuating type\" change curve of the water flow rate  
The \"multi peak fluctuating type\" change curve with flowing water is shown in Figure 10c,d. Figure 10c shows a type of water plugging failure. The initial water flow rate is maximum when \(JR\) C= 2-4, where the surface of the rough fracture is near the horizontal. The grout was taken away under the flowing water, and the blocking channel did not form. Thus, the grouting effect failed completely. Another situation of the multi peak fluctuating type is shown in Figure 10d, with the first phase from 0 to 67 s. There are many peak values owing to the large changes in the water flow. Chemical grout was injected into the fracture and the balance of the single flowing fluid was broken. From 67 to 73 s, temporary plugging formed, and the grout that had not completely solidified was washed away under the conditions of flowing water. The water flow fluctuated repeatedly with the continuous grouting. At 125 s, the water gushing channel was blocked by chemical grout, and the water flow showed an effective decline.