# Numerical Simulation of Rock Mass Structure Effect on Tunnel Smooth Blasting Quality: A Case Study
## 3 Results and Discussions
### Massive Integrity Structure Rock Mass  
The overbreak or underbreak rate of smooth blasting under different levels of each factor was sorted, and the single factor influence test results of each factor were obtained, as shown in Figure 11.  
Among the six test factors, the peripheral hole spacing had the most significant impact on the smooth blasting overbreak rate, and the overbreak percentage decreased steadily  
Figure 11: Overbreak or underbreak rate of smooth blasting under different levels of each factor in the massive integrity structure rock mass. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Test No. **} & \multicolumn{6}{c}{**Factors**} \\ \cline{2-7}  & \(\gamma\) (\({}^{\circ}  
with the increase in peripheral hole spacing. When the peripheral hole spacing increased from 40 cm to 80 cm, the overbreak rate decreased from 5.43% to 3.32%. The influence of the average spacing of structural planes was second only to the peripheral hole spacing. When the average spacing of structural planes was 3.0 m, the overbreak rate was 5.45%, and when the average spacing of structural planes increased to 4.0 m, the overbreak rate decreased to 4.01%, with a decrease of 35.91%. Thus, the average spacing of structural planes had a more obvious influence on the overbreak rate. The smaller the average spacing of structural planes was, the denser the structural planes, and the greater the overbreak rate. However, when the average spacing of structural planes was increased from 4.0 m to 5.0 m, the overbreak rate dropped from 4.01% to 3.50%, which was only 14.57%, and the decline of the curve greatly slowed down. When the average spacing of structural planes was greater than 4.0 m, its influence on the overbreak rate of smooth blasting was small. The influence of the angle between the structural plane trend and working face normal ranked third. The overbreak rate increased slightly with the increase in the angle between the structural plane trend and working face normal. When the angle between the structural plane trend and working face normal was 60\({}^{\circ}\), the overbreak rate was the largest. The overbreak rate increased with the increase in the dip angle of the structural plane, but the variation range was very small. The influence of the dip angle of the structural plane on the overbreak rate was much less than that of the average spacing of structural planes. The heading hole spacing and vertical spacing between the peripheral hole and the heading hole had a slight influence on the overbreak rate, and the curves were generally stable, which were not the main control factors of overbreak rate. Taking the overbreak rate of smooth blasting as the research object, the membership value of each factor index and the fuzzy comprehensive evaluation value are shown in Table 9.  
According to the main effect analysis of fuzzy mathematics theory, the maximum membership degree of the angle between structural plane trend and working face normal, average dip angle of the structural plane, average spacing of structural planes, peripheral hole spacing, heading hole spacing, the vertical spacing between the peripheral hole and the heading hole was \(\hat{F}_{7}~{}=~{}0.223\), \(\hat{F}_{a}~{}=~{}0.215\), \(\hat{F}_{D}~{}=~{}0.257\), \(\hat{F}_{P}~{}=~{}0.258\), \(\hat{F}_{H}~{}=~{}0.215\), and \(\hat{F}_{S}~{}=~{}0.204\), respectively. The maximum membership degree represented the influence of the specified factor on the evaluation index, and the value ranges from 0 to 1. The larger the value, the more obvious the influence of the factor on the evaluation index. Considering that \(\hat{F}_{p}>\hat{F}_{D}>\hat{F}_{\gamma}>\hat{F}_{H}>\hat{F}_{a}>\hat{F}_{S}\), the order of the influence weights of these six factors was as follows: peripheral hole spacing, average spacing of structural planes, the angle between structural plane trend and working face normal, heading hole spacing, average dip angle of the structural plane, and vertical spacing between the peripheral hole and the heading hole.