## 3 Results
### Rock Displacement Patterns Under Different Delay Time Conditions
(25 ms (**a1**), 50 ms (**a2**), 75 ms (**a3**) represent the delay times of 25 ms, 50 ms, and 75 ms for  
the internal rock movement after the detonation of the first row of blast holes; 25 ms (**b1**), 50 ms (**b2**), 75 ms (**b3**) represent the same delay times for the second row; 25 ms (**c1**), 50 ms (**c2**), 75 ms (**c3**) for the third row; 25 ms (**d1**), 50 ms (**d2**), 75 ms (**d3**) for the fourth row; 25 ms (**e1**), 50 ms (**e2**), 75 ms (**e3**) for the fifth row; and 25 ms (**f1**), 50 ms (**f2**), 75 ms (**f3**) for the sixth row of blast holes, all indicating the subsequent internal rock movement). Under the 75 ms delay blasting condition, as illustrated in Figure 5, it was evident that before the detonation of the second row of blast holes, the farthest throw distance of the rock mass was 2.307 m, which was significantly greater than the throw distances observed under the 25 ms and 50 ms delays, providing a larger compensation space for the detonation of subsequent rows (75 ms (a3)). After the detonation of the second row of blast holes, the rock mass at the excavation face had been thrown out, and the compensation space in the area of the second row of blast holes was larger compared with the 25 ms and 50 ms delays (75 ms (b3)). Following the detonation of the third row of blast holes, the rock mass from the first two rows had the farthest throw distance among the three delay conditions, and it did not affect the outward movement of the rock mass in the area of the third row of blast holes (75 ms (c3)). After the detonation of the fourth row of blast holes, the outward movement trajectory of the rock mass within the upper compensation space was clear, and it did not impose a restrictive effect on the movement of the lower rock mass, with the movement distance of the rock mass near the roof being larger than that under 25 ms and 50 ms delays (75 ms (d3)). Upon the detonation of the fifth row of blast holes, the rock mass in the upper area had been thrown out, providing a compensation space for the movement of the lower rock mass, and no restrictive effect occurred (75 ms (e3)). After the detonation of the bottom holes, a concave groove was also formed, indicating a root phenomenon, but the amount of rock mass in the upper area was significantly less than that under 25 ms and 50 ms delays, with more rock mass having been thrown beyond the free face (75 ms (f3)). Based on the study of the internal movement patterns of rock mass, a demonstration analysis of the overall movement trend of blasted rock mass was conducted, as illustrated in Figure 6a-e. These figures depicted the outward throwing movement cloud maps of the rock mass after the detonation of the second to sixth rows of blast holes, respectively, reflecting the spatiotemporal evolution pattern of rock mass movement at the excavation face post-blasting. From these cloud maps, it was observed that the rock mass at the excavation face first fell to the bottom of the blast heap, exhibiting a top-down collapse of the rock mass at the excavation face and a bottom-up stacking effect of the blast heap. In the simulation, tensile fracture phenomena appeared in the FEM elements at the upper roof. Subsequent field blasting tests confirmed that this manifested as scaling on both sides of the tunnel at the roof, consistent with the tensile fracture observed in the FEM elements at the roof in the numerical simulation, as shown in Figure 6f-h.