# Theoretical Study of Large Uncoupling Coefficient Loading for Surface Blasting
## 6 Conclusions  
(1) According to the assumption of detonation, the theory of smooth blasting has certain limitations in the application of a large non-coupling coefficient charge in smooth blasting. Therefore, it is discussed from the detonation theory that the uncoupled charge of air space charge meets the critical uncoupling coefficient of multi-exponential expansion, and according to the structural requirements of smooth blasting and field charge, the  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Rock Type** & \begin{tabular}{c} **Hole** \\ **Diameter (mm)** \\ \end{tabular} & **Charge Structure** & \begin{tabular}{c} **Uncoupling** \\ **Coefficient** \\ \end{tabular} & \
\begin{tabular}{c} **Hole** \\ **Spacing (m)** \\ \end{tabular} &
\begin{tabular}{c} **Line Charge** \\ **Density (g/m)** \\ \end{tabular} & **Effect** \\ \hline \hline Yanshanian granite & 90 & Uncoupled charge & 2.4 & 1 & 300 & Favorable \\ \hline Weakly weathered gneiss & 110 & Uncoupled charge & 3.5 & 1 & 350 & Favorable \\ \hline Limestone & 140 & Uncoupled charge & 3.5 & 1.2 & 300 & Favorable \\ \hline Mixed granite & 100 & Uncoupled charge & 2.5 & 1.2 & 500 & Favorable \\ \hline \hline \end{tabular}
\end{table}
Table 3: Blasting parameters of this case.  
Figure 7: Blasting effect diagram.  
equivalent relationship between an axial and radial uncoupling coefficient is established by deducing the quasi-static pressure, uncoupling coefficient, and hole spacing under a large uncoupling action. The theoretical relationship between an uncoupling coefficient and hole spacing is proposed, and it is revealed that the mechanism of selecting different smooth blasting parameters can achieve good results in engineering practices.  
(2) A slope in Guizhou was taken as an example for calculations and applied to the field charge. There are two kinds of charge structures with large uncoupling coefficients on site: one is the explosive equivalent diameter of 45 mm, the gun hole diameter of 90 mm, the gun bore directional uncoupling of 2.0, and the axial uncoupling coefficient of 4.0; the other is the explosive equivalent diameter of 32 mm. The hole diameter is 90 mm, the uncoupling coefficient of the gun aperture is 2.8, and the axial uncoupling coefficient is 2.2. The two charging structures have obtained good smooth blasting effects in field applications.  
Conceptualization, M.W. and H.W.; methodology, M.W.; software, Q.Z.; validation, M.W. and H.W.; formal analysis, Q.Z.; investigation, FX.; resources, Q.K.; data curation, H.W.; writing--original draft preparation, H.W.; writing--review and editing, M.W.; visualization, Y.P.; supervision, C.Z.; project administration, Q.Z.; funding acquisition, M.W. All authors have read and agreed to the published version of the manuscript.  
Anhui University Scientific Research Project, China (No. 2022 AH050841), and the National Natural Science Foundation of China (Grant No. 52209148). The open fund of State Key Laboratory of Coal Mine Disaster Dynamics and Control (2011 DA105827-FW202209). Anhui Key Laboratory of Mining Construction Engineering (GXZDSYS2022101).  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflict of interest.