## 5 Experimental Data Analysis
### Total Station Data Analysis
#### 5.3.2 Analysis of Subsidence Curves for the Overburden Rock Layer  
Based on the subsidence data measured from the four rows of points above the opening cut, curves were plotted to represent the subsidence of each row of measurement points as a function of the applied load.  
Figure 13: Scatter plot of measurement points: (**a**) scatter plot of measurement point distribution before loading, (**b**) comparison of measurement point distribution after loading with pre-loading data.  
From Figure 14a, it can be observed that when the model was loaded to 12 kN, the subsidence at each point changed slowly. However, after reaching 13 kN, the overall deterioration of the model accelerated, leading to a marked increase in the displacement and subsidence trends of all measurement points. Notably, the subsidence values after the final loading were significantly greater than those recorded during the 19 th loading cycle (15 kN). Additionally, the subsidence on the left side of the model was greater than that on the right side, with the measurement points directly above the opening cut showing greater subsidence than those on the sides. Among these, Measurement Point a4 recorded the maximum subsidence of 28 mm, while Measurement Point a10 on the right side showed the minimum subsidence of 9 mm.  
Figure 14: Subsidence curves: (**a**) subsidence curve of the first row of measurement points above the overburden rock layer as a function of load, (**b**) subsidence curve of the second row of measurement points above the overburden rock layer as a function of load, (**c**) subsidence curve of the third row of measurement points above the overburden rock layer as a function of load, (**d**) subsidence curve of the fourth row of measurement points above the overburden rock layer as a function of load, (**e**) subsidence curve of the 5 measurement points along the centerline as a function of load.  
Figure 14b presents the subsidence curve for the second row of measurement points, exhibiting a similar trend to that of the first row. Here, Measurement Point b4 also recorded the maximum subsidence of 28 mm, while Measurement Point b10 showed the minimum subsidence of 8 mm. Figure 14c,d indicate that the measurement points in the third and fourth rows follow a similar pattern to those in the second row.  
Figure 14e shows the subsidence change curves for four measurement points (a5, b5, c5, d5) along the centerline of the model as a function of loading cycles. It is clear that prior to the 15 th loading cycle, the subsidence curves were relatively flat, with minimal changes in subsidence. However, after the 17 th loading cycle (13 kN), the curves steepened, indicating significant changes in subsidence, particularly after the 20 th loading cycle when the model experienced substantial damage, resulting in greater changes compared to the 19 th loading cycle. The displacement curve for Measurement Point d5 consistently remained below the other three curves, indicating that d5 experienced greater subsidence, with delamination reaching up to 2 mm. The curves for the other three points largely overlapped, suggesting that the overburden rock layers remained intact and exhibited overall subsidence under pressure.