# Fractal Behavior of Size Distribution and Specific Surface Area of Blasting Fragments
## 5 Conclusions  
Through multiple field blasting experiments and indoor measurements of shape parameters of selected blasting fragments, the fractal characteristics of rock blasting fragments were investigated. The probability of rock blasting fragmentation was determined using the fragmentation fractal dimension, and a predictive formula for the SSA of blasting fragments was established. The following conclusions were drawn:  
1. According to the particle size-frequency relationship, the fractal dimensions of the particle size distribution calculated using different characteristic sizes were all less than 2, and the characteristic size significantly affected the computed fractal dimensions of the particle size distribution.
2. Depending on the excavation methods, blasting parameters, and other factors, blasting experiments with multifractal characteristics exhibited significant variations in the scale-free intervals and fragmentation fractal dimensions. In the larger scale-free interval, the fragmentation fractal dimensions were mostly greater than 2.3, whereas in the smaller scale-free interval, they were often less than 2.0.
3. Rock blasting fragmentation mainly involved two or three stages of fragmentation, with a similarity ratio of 0.5. The calculated average fragmentation probabilities of rock blasting ranged from 0.44 to 0.71. At the same bench height, blasting fragmentation with shock-reflection devices strengthened the transmission and reflective effects of stress waves, increasing the fragmentation probability and fragmentation efficiency of the rock mass.
4. The SSA of blasting fragments was closely related to the fragmentation fractal dimension and median particle size. By determining the SSA of blasting fragments with large particle sizes using 3D laser scanning technology in advance, the SSA of blasting fragments with a wide grading range can be easily calculated via the SSA predictive formula.  
Conceptualization, R.L., S.L. and W.L.; methodology, R.L., Y.L. and P.Z.; software, C.D.; validation, S.L., Y.L. and W.L.; formal analysis, C.D.; investigation, P.Z., C.D. and Y.L.; resources, S.L., P.Z. and W.L.; data curation, C.D. and Y.L.; writing--original draft preparation, R.L. and P.Z.; writing--review and editing, R.L., Y.L. and P.Z.; visualization, C.D. and Y.L.; supervision, S.L., Y.L. and W.L.; project administration, P.Z. and S.L.; funding acquisition, R.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Open Research Fund Project of Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources, Yangtze River Scientific Research Institute (Grant No. CKWV20221012/KY), and the Major Science and Technology Program (201 Program) of PowerChina Huadong Engineering Corporation Limited (Grant No. KY2021-ZD-01).  
Not applicable.  
Data Availability Statement: The data that support the findings of this study are available from the corresponding author upon reasonable request.  
This work was completed with the contributions of many researchers and their achievements, to whom the authors express gratitude. To avoid omissions, we express thanks to all contributors.  
Authors [PERSON], [PERSON], [PERSON] and [PERSON] were employed by the company Zhejiang Huadong Engineering Construction Management Company. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.