# Stability Analysis of Roadway Groups under Multi-Mining Disturbances
## 3 Theoretical Analysis
### Advanced Influence of Key Strata Collapse  
Using the empirical analogy method, the surface moving basin is gradually formed during the propelling of the working face. When the working face is propelled forward (1/4 _to 1/2_)_H_ range from the open-off cut, the mining influence can reach the surface causing the surface subsidence [27]. This is evidenced by the existence of large areas of subsidence around mines. Therefore, the following relationship between the advancing distance \(x\) of the working face and the height of the roof fracture sinking \(h(x)\) can be written:  
\[h=h(x)=0.25x \tag{1}\]  
According to the previous studies [28; 29] and the empirical range, the working face propelling distance \(x\) and the crossover influence distance \(f(x)\) have the functional relationship as follows:  
\[f=f(x)=0.125x \tag{2}\]  
The roof fracture of the working face is controlled by the key strata. Starting from the roof corresponding to the coal 3 under No. 45 strata, the height of the key strata, and its corresponding working face propelling distance and influence distance are shown in Table 2. Therefore, the relationship between the propelling distance of the working face and the height of the roof rock strata collapse and the influence height can be obtained, depicted in Figure 7. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Key Strata** & \begin{tabular}{c} **Key Strata** \\ **Height/m** \\ \end{tabular} & \begin{tabular}{c} **Caving** \\ **Height/m** \\ \end{tabular} & \
\begin{tabular}{c} **Mining** \\ **Distance/m** \\ \end{tabular} &
\begin{tabular}{c} **Affect the** \\ **Distance/m** \\ \end{tabular} \\ \hline inferior key & 7.6 & 26 & 1.90 & 3.25 \\ strata 1 & & & & \\ inferior key & & & & \\ strata 2 & & & & \\ inferior key & & & & \\ strata 3 & & & & \\ inferior key & & & & \\ strata 4 & & & & \\ inferior key & & & & \\ strata 5 & & & & \\ main key strata & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Propelling distance and influence values. Figure 7: Relation between working face propel distance and roof caving height and influence distance. According to Figure 7, as the working face propels, the roof collapse height increases. When the propelling distance of the working face reaches 250 m, the subsidence of the roof affects the ground, causing surface subsidence. The minimum mining advance distance of the working face is 92.35 m. The distance between the stop-mining line of the working face and the roadway is 100 m; the corresponding rock strata above the roadway are not affected by the collapse range. Jining No. 2 Coal Mine \(-\)740 m level four lanes, is an important throat connecting the south wing of the mountain and mining area 9, 13. With the mining on the working faces of both sides of the main roadway, the advanced abutment pressure impacts the stability of four main roadways at the \(-\)740 m level, leading to roadway deformations and break of roadway surfaces. The size of the working face and the distance from the adjacent roadway are listed in Table 3.  
According to the calculations, during the mining process of working face in Mining Area 11, the distance between \(-\)740 m level auxiliary transportation roadway is relatively small. For example, the distance between 01 working face and auxiliary transportation roadway is 64.18 m, and the distance to the transportation roadway is 81.4 m. Therefore, the mining of the working face impacts the \(-\)740 m large roadway. During the mining process, the main roadway is influenced by dynamic and static loads generated by the advanced abutment pressure for a long time period. The distance from the working face 3 and working face 9 mining areas to the main roadway exceeds 92.35 m, and mining does not affect the main roadway. The distance of the stop-mining line is larger than the influence distance of the mining process of the working face.