*3.2. Deformation Law and Evolution of the Surrounding Rock of the Roadway under Different Positions*

Figure 30 shows the cloud map of the deformation of the surrounding rock of the roadway at different locations. According to the cloud map's data (Figure 31), the deformation curves of the surrounding rock of the roadway at different locations are drawn. When conducting an analysis along the vertical layer, the deformation volume of the roadway dug along the bottom slab is the largest, the deformation of the surrounding rock mainly appears in the positive gang and the top slab of the roadway, and the deformation of the positive gang of the roadway is about 27 mm. The deformation of the top slab is about 28 mm, and the deformation of the negative gang is smaller at about 13 mm. The bottom slab has almost no deformations at about 6 mm. When conducting an analysis along the horizontal layer, the deformation of the surrounding rock mainly occurs at the top plate and the negative gang of the roadway, and the bottom plate also has some deformations. The maximum deformation of the top plate of the roadway is about 140 mm, the deformation of the positive and negative helpers of the roadway is about 130 mm, and the deformation of the bottom plate is about 30 mm.

**Figure 30.** *Cont*.

**Figure 30.** Deformation cloud diagram of the roadway's surrounding rock at different locations. (**a**) Roadway excavation along the roof. (**b**) Roadway excavation leaves: top coal bottom coal. (**c**) Roadway excavation along the floor. (**d**) The coal column is 4 m. (**e**) The coal column is 8 m. (**f**) The coal column is 15 m. (**g**) The coal column is 25 m. (**h**) Roadway dug directly below the residual coal pillar.

**Figure 31.** Deformation curves of the roadway's surrounding rock at different locations.

#### *3.3. Analysis of Results*

According to Figure 32, when the horizontal distance of the roadway from the residual coal pillar remains unchanged, the deformation of the roadway excavation along the floor is the largest, which is 27 mm, and the deformation mainly occurs in the secondary gang and the top slab. When the roadway is dug along the top and left top bottom coal boring, the plastic zone of the roadway's surrounding rock is much larger than the range of the plastic zone when the roadway is dug along the bottom, which indicates that the deformation of the surrounding rock is smaller, and the roadway is more stable when the roadway is arranged along the top. However, based on the fact that the mine is mined by the caving mining method, the roadway's layout should be located in the middle and lower positions of the coal seam.

**Figure 32.** Principal stress distribution and the plastic zone area under different roadway layout positions.

When the vertical direction of the roadway remains unchanged, the deformation of the roadway and the range of the plastic zone increase with the increase in the size of the left coal pillar. When the roadway is arranged directly below the residual coal pillar, the deformation of the roadway reaches the maximum, the maximum deformation of the top plate of the roadway reaches 140 mm. The deformation of the two helpers also reaches 130 mm, and the plastic zone is connected with the plastic zone of the residual coal pillar. This indicates that this location is most prominently affected by the concentrated stress of the residual coal pillar, and the roadway's stability is poor. With the comprehensive analysis conducted above, in the process mining a close coal seam group, the stress influence of residual coal column on the roadway is reduced and can effectively improve the stability of the roadway.

#### **4. Discussion**

For the analysis of roadway deformation variables, distinct from the long-term displacement monitoring methods used in the past [22], short-term surface displacement monitoring methods were used in this study to analyze roadway deformation variables. Long-term displacement monitoring methods can measure the deformation of the roadway more accurately, and air can be used to analyze the deformation and damage law of the roadway with a large amount of long-term data to obtain more accurate information on the deformation and damage mechanisms of the roadway. However, in the actual production process, when the roadway experiences excessive deformation or even closure, short-term surface displacement monitoring methods can be used to analyze the damage pattern of the roadway. Combined with the geological environments in which the roadway is

located, it is clear that in the non-uniform stress field, the roadway exhibits asymmetric damage morphologies.

In order to guarantee the stability of the roadway and to improve the support efficiency, FLAC3D numerical simulation software was used to establish a numerical model for the multi-point roadway arrangement, and the main stress values, the ratio of main stresses, the deformation variables of the roadway, and the connectivity between the roadway and the plastic zone of the residual coal column were analyzed in detail from different directions. In previous studies, the connectivity of the plastic zone was not used as a criterion for measuring the stability of the roadway [32–35]. However, in the actual production operation, the plastic zone of the residual coal pillar is the damage range of the surrounding rock. If the roadway and the plastic zone of the residual coal pillar appear in a superimposed area, then it will seriously affect the support of the roadway and cannot guarantee the stability of the roadway. In this study, the above factors were analyzed and combined with the mining processes adopted by the coal mine. It is proposed that, in the context of this type of project, the layout of the roadway in the middle and lower positions of the coal seam and the use of small coal pillars can guarantee the stability of the roadway.
