## 5 Conclusions  
This paper establishes a new method for evaluating the damage effect of rock under the action of explosion. The method analyzes the damage state of rock, and the distribution of explosive energy. Taking the Liyue Road Tunnel Project in Chongqing as an example, establish ten kinds of smooth blasting charge structure models. Based on the evaluation results, it preferred the optimal charge structure and explosive quantity. The method shows the feasibility and accuracy in the field test. 1. A method for evaluating the damaging effect of rock has been established based on the classical strength theory and damage fracture theory. The method divides the damaged area into two parts, takes dynamic tensile stress and damage variables as the key indexes, evaluates the numerical simulation results, and selects the preferred loading structure. Field tests verified the feasibility and accuracy of the method. 2. In the water interval charge structure, when the length of the water medium at the bottom of the hole is 20 cm, the damage range of the retained rock can be controlled while ensuring rock fragmentation. The length of the water medium at the orifice and in the middle of the hole is greater than 30 cm, which will affect the superimposed effect of the blasting stress wave, resulting in underdigging. 3. According to the evaluation results of the preferred charge structure, the length ratio of the upper and lower sections of explosives can reach 1:3, while the length ratio of the water medium is 2:2:1. In soft rock tunneling projects, the preferred charge structure reduces the amount of drugs by about 26% compared with the air-spaced charge structure, and the rate of half-hole traces is increased to 75%, which reduces the phenomenon of over-undercutting and the work of the secondary blasting, and significantly improves the operational efficiency. Conceptualization, S.W. and M.G. ; methodology, S.W. ; software, S.W. and H.W. ; validation, H.W. ; formal analysis, S.W. ; investigation, S.W. and M.G. ; resources, M.G. ; data  
Figure 17: Air interval and water interval smooth blasting profile forming effect: (**a1**) air interval, (**a2**) water interval, (**b1**) air interval, (**b2**) water interval. curation, S.W. and X.W. ; writing--original draft preparation, S.W. ; writing--review and editing, S.W., M.G. and X.L. ; visualization, S.W. and X.L. ; supervision, M.G. and X.W. ; project administration, M.G. ; funding acquisition, M.G. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Natural Science Foundation of China, grant number 52304204 and the China Postdoctoral Science Foundation, grant number 2022 TQ0025. Not applicable. The raw data supporting the conclusions of this article will be made available by the authors on request. The authors sincerely thank all the editors and reviewers for their support and help. The authors declare no conflicts of interest. The research was funded by the National Natural Science Foundation of China, grant number 52304204 and the China Postdoctoral Science Foundation, grant number 2022 TQ0025. Not applicable. The research was funded by the National Natural Science Foundation of China, grant number 52304204 and the China Postdoctoral Science Foundation, grant number 2022 TQ0025. * [PERSON] and [PERSON] (1971) [PERSON]; [PERSON] On the fracture process in blasting. _Int. J. Rock Mech. Min. Sci._**1971**, \(8\), 181-202. [CrossRef]
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