## 3 Theoretical Analysis  
### The Support Pressure Distribution Law of the Goal Area of the Previous Working Surface  
After the completion of face mining, the surrounding rock stresses near the goat will be redistributed, and the support pressure distribution [19] curve is shown in Figure 2. Among them, the low-stress area includes locations where the stress redistribution is small and the stress after plastic destruction is less than the stress of the original rock. The high-stress area consists of parts of the redistribution where the stress exceeds the original stress and parts of the original stress area that are not affected by the recovery. It can be clearly seen that when the roadway is excavated near the goat area, the roadway position directly affects the stability of the roadway, and if the roadway is excavated in the low-stress area of the surrounding rock, then the roadway will be conducive to maintenance. If the roadway is in the high-stress area of the surrounding rock, then the stability of the roadway will be greatly affected. If the roadway is excavated in the original rock stress area, then the coal column needs to be left wide, leading to a considerable waste of resources. The ventilation return lane is excavated on the side of the goat in working area 130,205. After monitoring and analysis of the ore pressure of working surface 130,203, the impact range of the support pressure is approximately 175 m, the peak supporting pressure is located at 20 m to 40 m on both sides of the working surface, the internal stress field range is within 10 to 12 m, and the external stress field range is outside of 12 m, as shown in Figure 2. The Yangchangwan Coal Mine preliminarily designed the ventilation return lane with a 35 m coal column; the width of the roadway is 5 m, and the roadway is in the range of 35-40 m. Since it is close to the peak area of support pressure, the roadway will have large deformation during excavation and maintenance. \begin{table}
\begin{tabular}{c c c c} \hline
**Location** & **Lithology** & **Thickness/[m]** & **Lithological Characteristics** \\ \hline Main roof & Medium sandstone & 12.7 & The color is off-white, containing long-term minerals and mud chips, mainly gelatinous calcium; good sorting; semicircular, developmental level layer. \\ \hline Immediate roof & Fine sandstone & 3.23 & Dark gray, mainly composed of long-term minerals and mud chips, mud calcareous cementation. \\ \hline Silstone & 4.62 & Dark gray, with a thin layer of fine sandstone in the upper part and a high argilla content in the middle. \\ \hline False roof & Carbonaceous peat & 0.4 & Black, containing a small amount of silt and pyrite, with brittleness, angular fractures, and stratigraphic development, relatively broken. \\ \hline
2 coal & Second layer of coal & 8.4 & Black, blocky, nonstick coal, mainly composed of semibright coal and silk charcoal, stepped fractures, striped structure, layered structure, stable deposition, simple structure. \\ \hline Direct bottom & Silstone & 1.44 & Black, black-gray, striped structure, block structure; the boundary line with the lower depression formation is obvious, and the coal line is partially thinned. \\ \cline{2-3}  & Two layers under the coal & 0.93 & Black, striped structure, broken step-like, with a clear boundary with the lower strata. \\ \hline Basic base & Silstone & 10.4 & Light gray, silty structure, block structure, thin coal line. \\ \hline \end{tabular}
\end{table} 
Table 1: Cont. In area 130,205 of the Yangchangwan Coal Mine, the excavation work was conducted in the previous period of work and a 35 m large coal column is still in used to protect the alley. The deformation of the weakly cemented surrounding rock is large (as described in Figures 3 and 4), and although the tunnel floor has been reinforced with grouting, there is still a bulging phenomenon occurring on the tunnel floor.