## 3 Field Test Analysis and Delay Adjustment Under Vibration Control
### Vibration Wave Arrival Time Sequence Analysis for Single Monitoring Point and Delay Adjustment
This multi-wave superposition effect significantly increases vibration amplitude, thereby elevating the probability of vibration hazards, with the HH2 direction precisely corresponding to the azimuth of monitoring points A1 and A2. In contrast, three directions (LH1, LH2, and LH3) exhibit low-probability vibration hazard characteristics, with monitoring points B1-B4 all located near the LH2 direction. When using the free face normal direction (LH1) as reference, the spatial distribution shows that HH1 and HH2 are situated in the lower-left and lower-right quadrants of the blast area respectively, while LH2 and LH3 are distributed on the left and right sides, respectively. Figure 14 presents analysis results after adjusting the initiation sequence based on monitoring point B1, demonstrating that adjustment focusing solely on this direction still leaves residual hazards and may lead to underestimation of vibration risks. To achieve comprehensive perimeter vibration control around the blast area, targeted adjustment must be implemented for high-probability hazard directions (such as the zones containing monitoring points A1 and A2). The monitoring points A1 and A2 exhibited the simultaneous arrival of vibration waves from six identical blast holes (#207, #214, #213, #215, #212, #211) within the 2730-2740 ms time window, as automatically identified by MATLAB. Following the wave separation methodology in Section 3.2, we implemented delay adjustment for these holes. Figure 15 shows the adjusted arrival-time distribution, where the maximum simultaneous waves were effectively controlled below four per window. The vibration profile at each monitoring point is divided into several time windows, and the number of simultaneous wave arrivals in each time window is not uniform, with m representing the maximum value of the number of vibration waves arriving at the same time, and n representing  
Figure 13: Distribution of maximum simultaneous wave arrival counts at monitoring points in the annular blasting area. (**a**) Before adjustment. (**b**) After adjustment. the number of points with such monitoring. The detailed view before adjustment seen in Figure 14 shows seven monitoring points with six simultaneous waves (completely eliminated post-adjustment) and thirty-five points with five waves (reduced to four, 88.57% reduction). The adjustment scheme, initiated at hole #207 (arrival time: 1800 ms) and concluding at #211 (2870 ms), applied progressive 50 ms (1/2T) increments to five consecutive holes (#214-#211), resulting in a cumulative 250 ms delay extension. Considering that the duration of the vibration curve of a single blast hole is 200 ms, the predicted vibration curves in the range of 1800 ms to 3320 ms were extracted for analysis. Figure 15 shows the comparison of the predicted vibration curves before and after the adjustment. Before the adjustment, the peak negative vibration velocity was \(-1.85\) cm\(\cdot\)s\({}^{-1}\), which decreased to \(-1.59\) cm\(\cdot\)s\({}^{-1}\) after the adjustment, with a reduction rate of 14.05%. Before the adjustment, the peak positive vibration velocity was 1.18 cm\(\cdot\)s\({}^{-1}\), which decreased to 1.10 cm\(\cdot\)s\({}^{-1}\) after the adjustment, with a reduction rate of 6.78%. The RMS values before and after the adjustment were 0.60 cm\(\cdot\)s\({}^{-1}\) and 0.49 cm\(\cdot\)s\({}^{-1}\) respectively, representing a decrease of 18.33% compared with the value before the adjustment. In vibration analysis, the logarithmic scale is usually expressed in the form of decibels (dB) and is calculated by the following formula:  
\[L_{dB}=20\log_{10}\left(\frac{PPV_{after}}{PPV_{before}}\right) \tag{8}\]  
where \(PPV_{after}\) is the effective value of the vibration after the delay adjustment and \(PPV_{before}\) is the effective value of the vibration before the delay adjustment. Figure 8:0 Distribution of maximum simultaneous wave arrival counts at monitoring points in the annular blasting area based on initiation sequence adjustment at monitoring point A1 and A2.