## 3 Results
### Stress and Damage Characteristics of Ore Rocks Under Different Delay Time Conditions
[37] observed that the ejection velocity of fragmented rock in bench blasting exhibited a pattern of acceleration, constant velocity, secondary acceleration, and deceleration. This study also identified similar patterns; however, these patterns were not evident with a short inter-row delay time of 25 ms but became more pronounced with a longer inter-row delay time of 75 ms. Comparative Verification of Rock Mass Movement and Ejection Blasting Experiments Under Different Delay Times  
In the field blasting comparison and verification experiments for rock mass movement, the confined space within underground tunnels and the constraints of objective conditions led to a relatively concentrated pile of blasted material. Nevertheless, the ejected material predominantly accumulated within 10 m of the excavation face under different delay time conditions as follows. Under the 25 ms delay condition, the blasting ejection distance was more concentrated near the excavation face, as illustrated in Figure 9 (25 ms (a)). The ejection distance was shorter, with the peak accumulation of the blasted pile located approximately 4.2 m from the excavation face, and the top width of the pile was about 1.8 m, with a curved distribution downward. Figure 9: Burst morphology and ejection distances at the blast site. Under the 50 ms delay condition, the blasting ejection distance was farther than at 25 ms, but the concentration degree of the blasted pile slightly decreased. The pile's accumulation pattern was similar to that at 25 ms, with the peak accumulation distance approximately 5.1 m from the excavation face and the top width about 1.2 m, displaying a curved distribution downward, as shown in Figure 9 (50 ms (c)). Under the 75 ms delay condition, the distribution characteristics of the blasted pile differed from those at 25 ms and 50 ms. The primary feature was a significant decrease in concentration, and no steep \"peak\" wave-like shape appeared near the excavation face. Instead, it exhibited a gentle \"slope\" shape, with distribution characteristics shown in Figure 9 (75 m s(e)). The overall ejected and accumulated pile characteristics under the three different delay time conditions are illustrated in Figure 9 (25 ms (b), 50 ms (d), and 75 ms (f)). The ejection distances of the piles were measured during the field experiments. Under the 25 ms delay condition, the pile was distributed within a 9.6 m range; under the 50 ms delay condition within a 13 m range; and under the 75 ms delay condition within a 17.2 m range. Hence, within a certain delay time range, the ejection distance of the blasted pile increased as the inter-row delay time increased, showing a transition from a concentrated accumulation near the excavation face to a more dispersed distribution towards the farther end. Additionally, a shorter inter-row delay resulted in a steeper pile, while a longer inter-row delay produced a gentler slope. The slope angle of the pile decreased with increasing inter-row delay time within a certain range. [PERSON], [PERSON] et al. [38] focused on the control of large fragments and concluded that the inter-row delay time for high bench cast blast should be between 63.5 ms and 102 ms, and should not exceed 100 ms. The findings of this study, indicating that a 75 ms inter-row delay time yielded better blasting results, were consistent with this conclusion. From the field blasting experiments, it was evident that the rock mass ejection patterns under different delay times were consistent with the trends observed in the numerical simulation analysis.