## 3 Gangue-Side Lateral Pressure-Control Technology
### The Reasonable Width Design of Roadway-Side Support  
Section 2.3 simplifies the mechanical equation of the slip surface when the roadside support body slips. By simplifying the parameters in the equation, the relationship between stability (i.e., the force on the roadside support body) and the coal seam mining height and the width of the support body is calculated, that is, Equation (19), which is similar to a binary relationship. If the sum of the two (coal seam mining height and support body width) is less than the maximum load that the support body can bear, the support body will slip and fail, indicating that its lateral bearing performance is insufficient. Therefore, when the coal seam mining height is determined, it is necessary to control the width of the roadside support body so that the load strength of the roadside support body does not exceed the slip stability characteristics under the influence of the width factor, so as to ensure the stability of the roadside support body. The mining height parameter in Figure 10 is set to 3.0 m. By setting the vertical section, the intersection line of the surface and the section is mapped to obtain Figure 22. Figure 22 shows the relationship between the width of roadway-side support and its lateral bearing strength.  
Figure 22: Relationship between the width of roadway-side support and its lateral bearing strength.  
A total of six different support body width schemes were set within the range of 1.0 m to 2.0 m, and the variation laws of the surrounding rock stress in the gob-side entry were obtained under different conditions [41; 42]. Figures 23 and 24 show the simulation results of lateral stress and plastic zone distribution of the gob-side entry support body under different width conditions. It is worth noting that the cutting angle refers to the angle between the roof cutting seam and the vertical plane. As the width of the support body increases, its lateral load also increases, and the lateral stress distribution overall presents a trend of initially increasing and then gradually stabilizing, enhancing the overall bearing capacity of the support body. The collapsed gangue, affected by the self-weight load of the overlying strata, generates lateral horizontal stress along the working face direction during the crushing and compaction process, exerting compressive force on the roadway-side support. The lateral load rapidly decays in the 0-0.3 m section from the base of the siltstone. When the width is 2 m, the maximum lateral stress reaches 2.12 MPa, and when the width is 1 m, the stress is 1.03 MPa. The lateral stress reaches a minimum at 0.91 m, with the minimum stress being 0.07 MPa when the width is 1 m. As the height increases, the stress gradually increases, but it remains below 1.5 MPa. As the support body width increases, the lateral horizontal thrust of the gangue pile decreases gradually.  
When the width of the roadway-side support body is less than 1.6 m, the variation in lateral load of the support body becomes more pronounced as the width increases, and a more stable elastic region gradually appears inside the support body. The overall bearing capacity of the support body increases. When the width of the support body exceeds 1.6 m, the variation in lateral load tends to stabilize as the width increases, and the elastic region remains essentially unchanged. This indicates the presence of an optimal threshold. By adjusting the width of the roadway-side support body, the strength of the support can be  
Figure 23: Distribution law of lateral stress of supporting body beside gob-side entry under different width conditions: (**a**) horizontal load curve of roadside support under different widths; (**b**) horizontal load distribution of roadside support under different widths.  
made to match its lateral load, thereby maintaining the stability of the entire support and achieving the goal of lateral load reduction. The overall bearing capacity of the support body increases, and the optimal width is ultimately determined to be 1.6 m.