# A Physical Model Test of Coal-Mining-Induced Deformation Mechanisms in a Canal
## 3 Physical Model Test
### Experimental Setup  
Based on the engineering geological conditions of the Gongmao mining area in Yuzhou in the middle route of the South-to-North Water Diversion Project, the geometric similarity ratio of the physical model test was set as 1:100, considering the test conditions and similarity theories. Firstly, the height of the overlying rock body and the soil mass at the bottom of the canal in the tested goaf were determined according to the engineering geological profile of the mining area; then, a steel frame model box was established, with a length, width, and height of 1400 mm, 400 mm, and 1400 mm, respectively. The front and rear facades of the model box were made of 10 steel plates which were 1400 mm long and 140 mm wide, respectively. Secondly, the rock mass was filled with the representative materials. The rock mass filling was divided into 7 layers; each layer of filler was 7 cm thick, and each layer of tamping was divided into 4 steps: paving leveling, initial tamping, heavy tamping, and leveling. In order for the two layers to be well cemented, the upper surface needed to be brushed. Finally, the loess soil layer was filled with raw materials, in line with the above steps, and the model at this point is shown in Figure 3. During the compaction of experiment materials in the test box, a steel plate was fixed on the side facade using bolts, which was replaced with a tempered glass plate of the same size before the test began, so as to observe and record the deformation and damage of the covered rock mass during the test.  
The model test mainly studies the deformation characteristics of the rock mass and the channel. Therefore, the deformation process of the overlying rock mass and the channel over the goaf was recorded. In order to measure the deformation characteristics of the upper rock mass, a square grid, 10 cm long and 7 cm wide, respectively, was drawn on the side facade. The deformation process of the side facade and the cross point of the grid line were regularly recorded by the 3D laser scanner. In order to measure the deformation process of the channel and the bank slope, a self-made deep displacement meter and a  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Raw Material** & **Fine Sand** & **Barite Powder** & **Gypsum** & **Alcohol** \\ \hline Ratio & 0.59 & 0.22 & 0.13 & 0.06 \\ \hline \end{tabular}
\end{table}
Table 1: Ratio of raw material for rock mass (mass ratio).  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Parameters** & **\(\gamma\) (kN/m3)** & **E/GPa** & **\(\mu\)** & **\(c\)/MPa** & **\(\varphi\)/(\({}^{\circ}\))** \\ \hline Grouted rock mass Representative materials & 21 & 1.5 & 0.28 & 0.6 & 31 \\ Similarity ratio & 21 & 0.015 & 0.28 & 0.006 & 31 \\ \hline \end{tabular}
\end{table}
Table 2: Physical and mechanical parameters of overburdened rock.  
displacement sensor were acquired, and the data acquisition frequency was 1 Hz. Vertical deformation measuring points of the same depth were arranged on the same side of the channel, monitoring points of different depths at the center and on the other side of the channel (Figures 3 and 4).