## 4 Onsite Blasting Experiments
### Results Analysis  
After the onsite experiment, the results were statistically analyzed. The rock blasting fragmentation results are shown in Figure 18a. Under the influence of explosive detonation, the rock was fragmented into varying sizes. The postblasting area was divided into several regions, with one region selected for further analysis, as shown in Figure 18b. A screening test of the rubble in this section was then conducted, as illustrated in Figure 18c. The screening process was conducted sequentially from larger to smaller particle sizes, ranging from 300 mm to 0.075 mm. The weight percentage of each particle size range was recorded, and a grading curve was generated based on the screening data. As shown in Figure 19, the resulting rock fragment distribution curve is plotted alongside the standard-prescribed envelope, where the lower and upper boundaries represent the allowable grading limits. For compliance, the rock fragment grading curve from blasting operations must lie entirely within these boundaries. However, the onsite experimental curve exceeded the envelope boundaries, failing to meet the required standard. As a result, a systematic analysis of the discrepancies was conducted to identify the root causes. The findings will be used to optimize onsite blasting parameters for future operations, ensuring adherence to design specifications. The results from the first onsite blasting experiment revealed two key issues: a lack of fine particles and a rock fragment grading curve (10-100 mm range) that fell below design specifications. This discrepancy is mainly due to the experiment being conducted during the early stages of mining, when no standardized procedures had been estab  
Figure 17: Photos of the onsite experiment. Figure 18: Onsite screening test. (**a**) After onsite blasting; (**b**) rock fragments in the selected region; (**c**) onsite screening test. lished. Additionally, the test results were significantly influenced by terrain, geological, and environmental factors. Another contributing factor is the rock composition, which predominantly consists of particles within the 10-100 mm range, leading to a higher proportion of such fragments after blasting. The data from the onsite experiment highlight the importance of considering rock fragment size distribution when designing blasting schemes. Predictive simulations of fragment sizes should be conducted in advance to ensure alignment with design requirements. Because the grading curve from the first experiment did not meet the standard, further studies were undertaken to explore the relationship between various blasting parameters and particle grading curves. To validate this approach, two additional onsite experiments were conducted, and the particle grading curves obtained from these tests are shown in Figures 20 and 21, demonstrating progressive alignment with design targets. The blasting parameters for the second onsite experiment were as follows: blast hole spacing of 2.2 m, row spacing of 2.0 m, drilling diameter of 115 mm, and the use of 90 mm emulsion explosives. An electronic detonator network was employed, and the blasting area was classified as loose blasting. The results of the second onsite experiment are shown in Figure 20. From the particle grading curve of the test results, it can be observed that parts of the grading curve for the sampled material slightly exceed the design envelope. The proportion of material in the 10-300 mm size range is slightly lower, indicating an excess of coarse particles. Specifically, \(d_{10}\), \(d_{30}\), \(d_{50}\), \(d_{60}\), and \(d_{63.21}\) fall outside the design requirements for particle fragment size distribution. Additionally, the nonuniformity coefficient (\(C_{u}\)) and the curvature coefficient (\(C_{c}\)) also fall outside the specified design requirements. The blasting parameters for the third onsite experiment were as follows: blast hole spacing of 1.8 m, row spacing of 1.8 m, drilling diameter of 115 mm, and continuous charging with 90 mm emulsion explosives.