## 3 Blast Design and Monitoring of Vibration
### Monitoring of Vibration  
There were many precise instruments and building structures that needed to be protected in the vicinity of the blasting area, such as the main generator room, curtain grouting area, tailgate pier, etc. Ubox-5016 piezoelectric vibration velocity sensors were used. The main performance parameters of the sensors were as follows:  
1. Maximum sampling rate: 200 ksps/channel.
2. Analog input channel: 1-4 channels/each device, multiple sets can be expanded in parallel.
3. Acquisition mode: multi-channel parallel acquisition.
4. Input signal bandwidth: 0-20 KHz.
5. Dc accuracy error: \(\leq\)\(\pm\)0.5%.
6. Amplitude range: 0.001-35.5 cm/s.  
Nine measurement points were arranged to monitor blast-induced vibration data in longitudinal, tangential, and vertical directions, as shown in Figure 2. On-site monitoring data of blast-induced vibration are shown in Figure 6.  
Figure 5: Typical blast parameters of region I. (**a**) Blast network structure, (**b**) A-A’ profile charge structure (unit:m).  
Altogether 1386 holes were detonated in land blasting. A total of 57 blast-induced vibration data were recorded as shown in Table 1. Among them, 18 measured data were in region I, 18 measured data were in region III, and 21 measured data were in region IV. The \(PPV\) in region I was 8.74 cm/s with an explosive charge weight per delay of 26.4 kg and total explosives charge weight of 2337.6 kg, at a distance of 15 m away from explosion source. In region III, the \(PPV\) was 7.03 cm/s and the explosives charge weight per delay and total explosives charge weight were 28 kg and 2578.9 kg at 18 m from explosion source. The \(PPV\) in region IV was 5.15 cm/s. The total explosive charge weight was 4724.8 kg with an explosive charge weight per delay of 28.5 kg at 20 m from explosion source. The \(PPV\) in the x (longitudinal), y (transversal), and z (vertical) direction can be found in Figure 7.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Region**} & \multirow{2}{*}{**Shot**} & **Charge** & **Total** & **Radial** & **Longitudinal** & **Transversal** & **Vertical** \\  & & **Weight Per** & **Charge** & **Distance** & **Velocity** & **Velocity** & **Velocity** \\  & & **Delay (kg)** & **Weight (kg)** & **(m)** & **(cm/s)** & **(cm/s)** & **(cm/s)** \\ \hline \multirow{4}{*}{I} & 1 & 26.4 & 2337.6 & 15 & 7.909 & 5.431 & 8.741 \\  & 2 & 26.4 & 2337.6 & 70 & 0.224 & 0.591 & 0.588 \\  & 3 & 26.4 & 2337.6 & 25 & 3.772 & 3.025 & 3.318 \\  & 5 & 26.4 & 2337.6 & 35 & 2.567 & 1.943 & 2.588 \\  &[PERSON]'s empirical formula is widely used to show the attenuation law of \(PPV\)[18]. Accordingly, \(PPV\) is related to the distance between the monitoring point and blast source \(R\), and the explosives charge weight per delay \(Q\).  
\[PPV=k(SD)^{-\alpha} \tag{1}\]  
where \(k\) is a coefficient in blast design, \(SD=R/Q^{1/3}\) is the scaled distance (m/kg\({}^{1/3}\)), \(R\) is the distance between the blast source and the monitoring point (m), \(Q\) is the explosives charge weight per delay (kg), and \(\alpha\) is the attenuation coefficient.  
According to the blast-induced vibration measured values in Table 1, \(PPV\) in different regions can be expressed as Figure 8.  
Figure 7: Time history curve of blast vibration of no. 1 monitoring point in region III. (**a**) X-direction velocity, (**b**) Y-direction velocity, (**c**) Z-direction velocity.