## 4 Application in Tunnel Smooth Blasting  
If the JH-2 damage constitutive model could be employed in the constructions of practical engineering, it would be of great help in terms of quality control and prediction in advance, which could improve safety during the constructions and reduce cost. In the case of tunnel excavation, for example, accurate prediction can help decrease the overbreak/underbreak and the vibration on the surrounding rock mass induced by blasting so as to the damage of the surrounding rock mass and improve the entire stability. In this study, the Zigaojian Tunnel of the Hangzhou-Huangshan high-speed railway, China, was chosen as a case study to simulate the process of smooth blasting excavation based on the JH-2 constitutive model. The bedded rock mass structure is distributed in a long (several miles) segment, which consists of large and long bedded discontinuities, occurring on average every 1.5 m and parallel with each other (see Figure 8). Smooth blasting method is used \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Constants**} & **Barre** & \multirow{2}{*}{**Sandstone**} & **Constants** & **Barre** & \multirow{2}{*}{**Sandstone**} \\  & **Granite** & & & & **Granite** & \\ \hline Density \(\rho_{0}\) (g/cm\({}^{3}\)) & 2.66 & 2.60 & \begin{tabular}{c} Hugoniot elastic limit \\ _HEL_ (GPa) \\ \end{tabular} & 4.5 & 4.5 \\ \hline Shear modulus \(G\) (GPa) & 21.9 & 17.8 & \begin{tabular}{c} HEL pressure \(P_{HEL}\) \\ (GPa) \\ \end{tabular} & 2.93 & 2.6 \\ \hline \begin{tabular}{c} Intact strength \\ coefficient \(A\) \\ \end{tabular} & 1.248 & 1.01 & Bulk factor \(\beta\) & 1.0 & 1.0 \\ \hline \begin{tabular}{c} Fractured strength \\ coefficient \(B\) \\ \end{tabular} & 0.68 & 0.68 & Damage coefficient \(D_{1}\) & 0.008 & 0.005 \\ \hline \begin{tabular}{c} Strain rate \\ coefficient \(C\) \\ \end{tabular} & 0.0051 & 0.005 & Damage coefficient \(D_{2}\) & 0.435 & 0.7 \\ \hline \begin{tabular}{c} Fractured strength \\ exponent \(M\) \\ \end{tabular} & 0.83 & 0.83 & Bulk modulus \(K1\) (GPa) & 25.7 & 19.5 \\ \hline \begin{tabular}{c} Intact strength \\ exponent \(N\) \\ \end{tabular} & 0.676 & 0.83 & \begin{tabular}{c} Second pressure \\ coefficient \(K2\) (GPa) \\ \end{tabular} & \(-\)386 & \(-\)23 \\ \hline \
\begin{tabular}{c} Maximum tensile \\ strength \(T\) (GPa) \\ \end{tabular} & 57 & 45 &
\begin{tabular}{c} Third pressure \\ coefficient \(K3\) (GPa) \\ \end{tabular} & 12,800 & 2980 \\ \hline \multicolumn{5}{c}{Maximum normalized fractured strength \(\sigma^{*}_{\text{Fmax}}\)} & 0.16 & 0.18 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Parameters of Barre granite and sandstone  
Figure 7: Relation of equivalent plastic strain failure against hydrostatic pressure for granite. in this tunnel, which means that the explosives detonate from the inner cut boreholes to the external peripheral boreholes in sequence and finally form a smooth tunnel profile. In general, the determination of rock mass classification is significant before designing for tunnels. Such classification includes information on the strength of the intact rock material, the spacing, the number and surface properties of structural discontinuities, as well as allowances for the influence of subsurface groundwater, in situ stresses, and the orientation and inclination of dominant discontinuities [54]. Many rock mass classification systems have been proposed to date, of which Terzaghi classification, Lauffer classification, Deere's rock quality designation (RQD), and Wickham's rock structure rating (RSR) are considered as the earlier main classification methods. However, the influences caused by the properties of discontinuities or intact rock material were disregarded in some of the previous classifications of rock masses [55]. [PERSON] [56; 57] developed a modified geomechanical rock mass rating (RMR) classification system, which is used for the design and construction of excavations in rock, such as tunnels, mines, slopes, and foundations. [PERSON] et al.