## 4 Results of Roadway Tunneling Simulation
### Energy Analysis of Coal Mass under Parameter Variation  
In order to predict the associated risks during roadway tunneling, the distribution of stress and deformation energy within the surrounding coal mass were examined. The main energy types involved in rock burst include elastic strain energy, plastic strain energy, and kinetic energy. Real-time monitoring of surrounding coal mass velocities can be realized by 3 DEC, and the kinetic energy for individual coal units can be calculated.  
Based on the analysis in Section 4.1, the roadway side area is particularly vulnerable to stress disturbances during tunneling. Figure 5 depicts the displacement change curves for the coal mass under varied parameter conditions discussed in Section 3.  
The observations from Figure 5 reveal that displacement on the roadway side is significantly influenced by variations in the mechanical parameters in the coal seam. Notably, during the middle stage of roadway tunneling, coal mass displacements experience sudden decreases over short periods. However, the total trends of the displacement curves for different parameter sets remain similar, suggesting that mechanical parameter variations do not drastically alter coal mass movement characteristics on the roadway side.  
The plotted curves can be classified into two categories, according to their peak displacements at inflection points: Category 1 (b\(\succ\)e, h, j) exhibits peak displacements above 0.14 m, whereas Category 2 (a, f, g, i) exhibits displacements below 0.1 m. Furthermore, the magnitude of the displacement decreases also show differences between the two groups.  
In summary, variations in coal seam parameters could affect peak displacements in the roadway side area during roadway tunneling, demonstrating the importance of parameter variation for predicting and managing rock burst hazards effectively.  
Figure 4: Plot of velocities at monitoring points versus time steps.  
The kinetic energy of the coal mass is determined using Equation (1) in the simulation process. The velocity change data of coal blocks at the roadway side position are recorded under parameter variation. Concurrently, considering the density of the coal mass and the model size calculation, the mass of an irregular coal block with a side length of 1 m is approximately 1 ton. The kinetic energies for ten groups of coal blocks are illustrated in Figure 6, below:  
\[U_{V}=\frac{1}{2}\sum_{i=0}^{n}m_{i}v_{i}^{2} \tag{1}\]  
where \(U_{V}\) is the kinetic energy of the coal mass; \(m_{i}\) is the mass of the \(i\)th coal block; and \(V_{i}\) is the velocity at the center of \(i\)th coal block.  
Figure 5: Plot of displacements on the tunnel roadway side versus time steps of different coal mass parameters.  
Figure 6: Plots of coal mass kinetic energy versus time steps for ten groups of parameters.  
Figure 6 demonstrates substantial changes in the kinetic energy of the coal block under varied parameter conditions. For Category 1, the peak kinetic energy values range from 290 to 626 J, with Group c displaying the highest value and Group b the lowest. Conversely, the kinetic energy values for Category 2 do not exceed 100 J. Group h reaches a peak of 50.3 J, whereas the other groups fluctuate around 17 J, showing no significant differences in peak values. A comparative analysis of Groups b to e reveals that the increase in both the internal friction angle and the cohesion enhance the kinetic energy of coal blocks along the roadway side, with cohesion having a particularly pronounced effect.