## 3 Results and Analysis
### Analysis of Surface Subsidence Completed by Different Methods of Goal Treatment  
The surface subsidence exhibited a significant reduction in the first year subsequent to the completion of goat treatment, leading to substantial modification of the surface subsidence curve compared to its pre-treatment state.  
Figure 7: (**a**) Comparison of the settlement of the monitoring points during the treatment period of the goat and before the treatment, (**b**) Comparison of the settlement of the monitoring point after the completion of the treatment of the goat and the treatment period.  
As shown in Figure 6a, specifically, the surface subsidence curve of the fully filled goaf exhibits a bowl-shaped profile with wide edges and a slightly curved bottom. The subsidence rates at A1, A2, A3, and A4 are 7.20 mm/year, 17.22 mm/year, 25.97 mm/year, and 30.56 mm/year, respectively. As depicted in Figure 7b, these values are lower than their respective pre-mining levels by 87.12%, 52.16%, 61.21%, and 71.89%. By comparing A1 and A2 with A3 and A4, it can be observed that the surface subsidence in the stable pillar area remains below 20 mm per year. In contrast, in the unstable pillar area, it still exceeds 20 mm per year. This indicates a gradual transfer of load from the pillars to both the backfill body and the pillars themselves. However, in the unstable pillar area, most of the load is borne by the compressed backfill body, resulting in a prolonged duration of movement for the overlying rock layer compared to that in the stable pillar area.
2. As shown in Figure 6b, the surface subsidence curve of the first year of local filling and reinforcement treatment in the goat exhibits a wave-shaped pattern characterized by two smaller subsidence basins. The subsidence rates for B1, B2, B3, B4, and B5 are 16.85 mm/year, 14.60 mm/year, 18.36 mm/year, 20.54 mm/year, and 35.35 mm/year, respectively. As illustrated in Figure 7b, compared to the treatment period, there was a reduction in the surface subsidence rate by 67.3%, 48.17%, 73.55%, 75.55%, and 33.24%, respectively. Upon comparative analysis, it is evident that the surface subsidence rate for unfilled and reinforced pillar treatment remains below the threshold of 20 mm/year; however, within the filling treatment area, it still exceeds this limit. The local filling treatment area (B2 and B5) demonstrates lower surface subsidence rates when compared to unfilled (B4) and reinforced pillar treatments (B1 and B3).
3. As shown in Figure 6c, the surface subsidence curve of the goaf in the first year of closed treatment exhibited a gradual decline, with subsidence rates of C1, C2, and C3 measuring 27.84 mm/year, 25.88 mm/year, and 22.56 mm/year, respectively. As illustrated in Figure 7b, these values have been reduced by 52.46%, 73.76%, and 72.51%, correspondingly. Upon comparison, it is evident that while experiencing a relatively smaller degree of reduction, the subsidence value of C1 surpasses that of C2 and C3. The subsidence rate at both ends of the goat is observed to be higher compared to that observed at the position of the unstable pillar, indicating a transfer of movement within the overlying rock layer from the unstable pillar toward both ends of the goat subsequent to its closure and treatment. As a result, surface subsidence continues to exceed 20 mm/year.  
The figure demonstrates that after a two-year goaf treatment, the surface subsidence curves of the three goaves exhibit a relatively gradual trend, with all surface subsidence rates measuring below 20 mm/year. This observation suggests a cessation in the movement of the overlying rock strata and effective control over surface subsidence.