## 3 Numerical Simulation Results
### Maximum Stress and Displacement around the Tunnel  
In order to explore the impact of blasting disturbance on the dynamic distribution of the tunnel, ten gauge monitoring points were set around the numerical model of the tunnel, and the stress distribution results were analyzed through the iterative operation of the numerical software AUTODYN. As can be seen from Figure 8, the pressure on the blasting side of the tunnel is the largest, and the maximum pressure is mainly concentrated at the arch foot and arch shoulder. For example, when the blasting source was located from the left side, the pressure at monitoring point #3 located at the arch foot was 48.72 MPa. When the blasting source was located above the roof, the pressure at monitoring point #1 located at the arch shoulder was 23.76 MPa. When the blasting source was located below the floor, the pressure at monitoring point #3 located at the arch foot was 48.76 MPa. From the perspective of pressure distribution, when the blast-facing side is an arch, the distribution of compressive stress at the arch is more uniform compared to the other two situations, and the average compressive stress around the roadway is also smaller. The arch can better resist impact loads such as blasting. Figure 7: Dynamic failure of the tunnel under blast stress wave. It can be seen from Figure 9, the maximum shear stress on the blasting side of the tunnel is mainly concentrated at the arch crown and arch foot. For example, when the blasting source was located from the left side, the shear stress at monitoring point #3 at the arch foot was 28.61 MPa. When the blasting source was located above the roof, the pressure at monitoring point #8 at the arch crown was 27.35 MPa. When the blasting source was located below the floor, the pressure at monitoring point #4 at the arch foot was 28.71 MPa. The distribution of shear stress is independent of the shape of the stressed surface, and the shear stress on the arch is even greater than that on the straight wall. Through monitoring data, it was found that the shear stress values at the symmetrical positions on the blasting side vary greatly; this may be caused by the inconsistent deformation of the tunnel after compression. Therefore, more attention should be paid to improving its shear strength when supporting the roof of the tunnel; this may be achieved through methods such as anchor bolts support. It can be seen from Figure 10, the horizontal/vertical stress on the blast-facing side of the tunnel is the largest, and the maximum shear stress is mainly concentrated at the arch shoulder and arch foot. For example, when the blasting source was located from the left side, the shear stress at the #3 monitoring point at the arch foot was 82.31 MPa. When the blasting source was located above the roof, the pressure at the #1 monitoring point at the arch roof was 48.82 MPa. When the blasting source was located below the floor, the pressure at the #3 monitoring point at the arch foot was 79.23 MPa. From the comparison between horizontal stress and vertical stress, the maximum vertical stress is 79.23 MPa, and the maximum horizontal stress is 82.31 MPa. The horizontal stress is significantly larger than the vertical stress, indicating that the stability of the tunnel in the horizontal direction is weaker than in the vertical direction when subjected to the same magnitude of loads. Therefore, when blasting construction is carried out near the tunnel, the support strength of the tunnel side wall should be strengthened. Figure 8: Compressive stress variation around tunnel model. Figure 9: Shear stress variation around the tunnel model. As can be seen from Figure 11, the displacement on the blasting side of the tunnel is the largest, and the maximum shear stress is mainly concentrated at the arch shoulder, arch crown point, and center of the floor. For example, when the blasting source was located from the left side, the shear stress at the #1 monitoring point at the arch shoulder was 109.25 mm.