## 4 Stress Distribution Law in Island Working Face
### Numerical Simulation Results Analysis
#### 4.2.2 The Stress Distribution Influenced by Adjacent Gob Length  
Under different lengths of the gob conditions, the stress distribution characteristics of the island working face are simulated, as shown in Figure 13a. The plastic zone range of the surrounding rock and the coal pillar of the roadway in the island working face gradually increases with an increasing length of the gob, and the peak stress gradually increases and moves to the center of the coal pillar and the deep part of the working face. Figure 13b shows the variation law of the coal pillar stress and the evolution characteristics of the plastic zone under different gob conditions. It can be seen from the figure that when the length of the gob is 100 m, 150 m, 200 m, and 250 m, the total proportion of grids in the plastic zone proportion of the coal pillar is 43.13%, 48.75%, 56.25%, and 65.00%, respectively, and the corresponding peak stress of the coal pillar is 24.7 Mpa, 30.3 Mpa, 33.5 Mpa, and  
Figure 12: (**a**) Stress distribution features of island working face under different buried depths; (**b**) the stress variation law and plastic zone evolution characteristics of coal pillar under different buried depths; (**c**) fitting curve of peak stress of entity coal and buried depth.  
37 Mpa, respectively, all of which show a gradual increasing trend. Within the length of the gob, although the proportion of the plastic zone of the coal pillar is increasing, a coal pillar with a width of 30 m still has good bearing capacity. It can bear greater stress without failure and instability.  
The relationship between the peak stress of the entity coal and the length of the gob is shown in Figure 13c. The peak stress of the isolated island working face is 24.9 Mpa, 27.3 Mpa, 32.2 Mpa, and 33.9 Mpa, respectively, showing a gradual increasing trend. With the increase of the gob length, the damage range of the overlying strata in the gob is correspondingly expanded, resulting in more overlying strata gravity transferring to the underlying coal body. Although the proportion of the plastic zone range of the coal pillar is  
Figure 13: (**a**) Stress distribution features of island working face under different gob lengths; (**b**) the stress variation law and plastic zone evolution characteristics of coal pillars under different gob lengths; (**c**) fitting curve of peak stress of entity coal and gob length.  
gradually increasing, there are still enough elastic cores inside it, showing good bearing capacity. Therefore, the stress of the coal pillar is also increasing. At the same time, the stress on the entity coal is also increasing accordingly, and this stress gradually expands to the deep coal seam. This series of changes shows that when the range of gobs on both sides increases, the stress concentration degree of the island working face will also increase. Therefore, it is crucial to carefully arrange the mining area layout in the mining design to minimize the presence of large gob areas. This strategy aims to decrease the level of stress concentration and enhance the safety of working face mining.