## 4 Discussion and Conclusions  
The findings of this study have important implications for engineering practice, particularly in the design and optimization of strata control measures in response to varying mining heights and advancing rates. The sensitivity analysis demonstrates that both mining height and advancing rate significantly influence overburden behavior, including stress redistribution and surface settlement. These results suggest that excavation parameters should be closely integrated with ground control strategies to ensure safety and efficiency. Excavation progress leads to the redistribution of in situ stress and fracture generation among overburdened strata, and a seismic event may happen during this process. In this paper, numerical modeling is conducted to investigate the sensitivity of three main parameters, including Young's modulus, mining height, and advancing rate. The results indicate that Young's modulus of the key strata generally has the greatest impact on the principal stress distribution but has limited influence on the settlement. In contrast, mining height has a greater influence on the total settlement of the overburden strata. The advancing rate can vary the fluctuation of the principal stress and the settlement, but has little influence on the final stress distribution and the settlement, which is reasonable due to the time effect of deformation. Physical modeling is also conducted to simulate the actual mining conditions of engineering and intuitively study the propagation of cracks. The observation from the physical experiment basically agrees with the result of the modelling simulation. Collapse occurs in the early stage of excavation, and cracks appear at the top of the model. Both vertical and horizontal cracks can be found in the excavation process. It is suggested that the grouting and shotcrete in excavation, which can increase the stiffness of the stratum or the surrounding rock, can effectively decrease the settlement in addition to the stability. One practical engineering strategy proposed in this research is to improve the stiffness of the primary key stratum through targeted grouting reinforcement, thereby increasing its effective Young's modulus. By enhancing the mechanical properties of this control layer, stress concentrations around the mining area can be reduced, and vertical displacement of the overburden can be effectively constrained. Grouting is particularly useful when key strata exhibit low elastic modulus and high stress concentration zones are identified. Shotcrete is recommended during early-stage excavation to enhance the stiffness of the surrounding rock mass near the working face. Numerical results show that increasing the  
Figure 17: The typical crack development and collapse model. modulus of the key stratum leads to a more uniform stress distribution and less deformation at the surface, especially under high mining height or rapid advance conditions. In addition, the results indicate that different combinations of mining height and advance rate produce varied overburden responses, highlighting the necessity for flexible and adaptive support systems. For example, in cases with high mining heights, stronger immediate roof support and wider reinforcement zones may be required. When a faster advance rate is adopted, time-dependent deformations become more significant, and preemptive grouting or stress-relief techniques should be applied in advance. This research primarily investigates the impact of mining technology parameters under certain conditions. However, it is limited to these specific conditions and does not encompass other possible complicated scenarios in real engineering. This simplified method is suitable for mechanism analysis and preliminary exploration of parameter sensitivity. For future research, methods such as Monte Carlo methods or random field modeling are planned to be employed to better capture the discrete and uncertain nature of geological parameters.