## 3 Rock Breaking Design Program
### Dynamic Blasting
#### 3.1.2 Monitoring and Fitting
For the upper bench blasting of the tunnel face at section YK9+082, the calculated PPVs for the underground pipelines and high-speed rail line are found in the first segment (with a Q of 4 kg), which are 6.33 cm/s and 0.76 cm/s, respectively, which are less than the specified PPV control value. Therefore, the settings of the blasting parameters for the upper and lower benches are reasonable. Their specific calculation results are shown in Figure 6.  
(2) Collaborative dredging  
The project overview confirms that the minimum clear distance of the underground pipeline from the tunnel bottom at the highway central divider is only 4.64 m. Therefore, in this blasting design, it is assumed in the limit case that the highway central divider, the blasting tunnel face and the underground pipeline are in the same plane. Theoretically the maximum PPV will occur in this section. If the PPV at the tunnel face satisfies the vibration velocity provisions, the PPV at the section between the YK9+082 and YK9+150 should be within the safety limit. The calculation method is the same as the previous drilling and blasting method, and the calculation results are shown in Figure 7. It can be seen that when the underground pipeline is located directly above the guided blasting, the PPV of the highway roadbed, underground pipeline and high-speed rail line are in the 15 th segment (with Q of 1 kg), the 13 th segment (with Q of 0.6 kg), as well as in the 13 th and 15 th segments (with Q of 1 kg), respectively, which are 4.83 cm/s, 6.10 cm/s and \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Location** & **PPV Control Value (cm/s)** & **R at Minimum PPV (m)** & **Q (kg)** \\ \hline HR & 7 & 5.70 & 0.53 \\ UP & 7 & 4.64 & 0.29 \\ HSRT & 1 & 50.00 & 5.15 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Maximum section explosive charge in limit cases. 0.47 cm/s, respectively, which are less than the specified PPV limit, indicating that the blasting parameters of the lower bench meet the safety requirements. (3) Numerical simulation of explosive blasting under three operating conditions  
Conventional blasting for the proposed tunnel is a design based on the protection of adjacent projects. The highway in operation, the fully enclosed high-speed railway line, and the inaccessible underground pipeline make it impossible to carry out large-scale on-site monitoring. Therefore, it is necessary to verify the design through numerical simulation and analyze the stresses of the structure under the limit conditions, to provide a basis for a comparative analysis between the HPGEM and dynamic blasting. Considering that the excavation of the left tunnel has been completed, and the two tunnels are not adjacent tunnels, only the right tunnel of the proposed tunnel is considered in the numerical model. Numerical simulations were performed to investigate the vibration velocity and force of the highway roadbed, underground pipeline, and high-speed rail line during dynamite blasting under three working conditions. According to the relative position relationship of each structure and the geological conditions, the model size is 160 m \(\times\) 80 m \(\times\) 100 m (long, high, wide). The element of the model is solid-164. The three main materials used in the model are explosives, rock, and  
Figure 6: Calculation results of PPV during the construction of upper and lower step drilling and blasting method (YK9+082). Figure 7: Calculation results of PPV with the guide hole cooperative excavation method (YK9+082). concrete. C30 concrete is considered for the highway roadbed, and the explosives are the No. 2 rock emulsified explosives. The equation of state is defined as follows:  
\[P=A\bigg{(}1-\frac{\omega}{R_{1}V}\bigg{)}e^{-R_{1}V}+B\bigg{(}1-\frac{\omega}{R_ {2}V}\bigg{)}e^{-R_{2}V}+\frac{\omega E}{V} \tag{8}\]  
where \(P\) is the blasting pressure (MPa); \(V\) is the relative volume; \(E\) is the internal energy per unit volume (GPa); and \(\omega,A,B,R_{1},R_{2}\) are the material constants.