## 5 Dynamic Pressure Control Technology for a Roadway's Surrounding Rock
### Numerical Simulation Analysis of the Support Effect
#### 5.3.2 Effect Analysis  
According to the numerical simulation findings, an analysis was conducted on the displacement and plastic zone of the roadway surrounding rock. This analysis considered both regular anchor cable support and reinforcement with combined brackets.  
(1) Displacement analysis  
Figures 15 and 16 show the vertical and horizontal displacement distribution of the roadway under dynamic pressure with different support schemes. The reinforced support scheme significantly reduces the deformation of the surrounding rock. It is evident that the subsidence of the roadway roof using the original support is 95.5 mm, the floor heave is 13.3 mm, the left side has moved 76.5 mm, and the right side has moved 81.9 mm. When the combined bracket is used to reinforce the roadway, the vertical displacement of the roof is 79.8 mm, the floor heave is 10.4 mm, the left side has moved 60.1 mm, and the right side has moved 65.4 mm.  
Figure 14: Simulation of different support schemes. (**a**) Support of anchor bolts and anchor cables. (**b**) Combined support of the anchor bolts, anchor cables, and combined bracket.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Support** & **Diameter (mm)** & **Cross-Section** & **Poisson’s Ratio** & **Elastic** & **Polar Moment** & **Z Moment** \\
**Formation** & & **Area (mm\({}^{2}\))** & **Mo  
Compared with the original scheme, the reinforcement support scheme has optimized the support effects aimed at limiting roof subsidence, floor heave, and side convergence by 16.4%, 21.8%, and 20.8%, respectively. The impact on controlling the deformation of the surrounding rock is clearly evident.  
(2) Plastic zone analysis  
Figure 17 illustrates the distribution of the plastic zone of the roadway surrounding rock when subjected to dynamic pressure, considering various support schemes. When the original support scheme is adopted, the plastic zone is primarily concentrated at the roof and sides, with a distinct development of a plastic zone at the shoulder angle. Meanwhile, since the floor is siltstone with relatively good lithology, the plastic zone exhibits a limited extent. Under reinforced support, the plastic zone at the shoulder corner of the roadway is significantly weakened and is mostly concentrated above the roadway roof, while the plastic zone at the bottom corner is increased.  
Figure 16: Horizontal displacement distribution of the roadway’s surrounding rock.  
Figure 17: Boundary of the plastic zone of the roadway’s surrounding rock.  
Figure 15: Vertical displacement distribution of the roadway’s surrounding rock.  
Combined with the analysis of the on-site conditions, it is believed that the roof surrounding rock has a certain degree of pressure relief effect after the use of the combined bracket reinforcement scheme, and the combined bracket can play a passive supporting role, which makes the plastic zone of the shoulder angle of the roadway reduced to a certain extent, while the concrete filled steel tube columns on both sides are affected by the advanced supporting pressure, resulting in an increase in the plastic zone of the bottom corners.