## 5 Conclusions  
In this paper, for a roadway expansion project of the central transportation lane of the mine, the mechanical parameters of the roadway surrounding rock was tested, the expansion properties of the static crushing agent (SCA) with different water-cement ratios were obtained, and then, the cracking process of the surrounding rock by SCA was also characterized using laboratory tests and numerical simulation. Finally, using SCA technology to expand the roadway was proposed, and the construction effect on the roadway expansion project was discussed. The following conclusions can be obtained:  
(1) For a roadway expansion project, the mechanical parameters of the surrounding rock can be obtained by laboratory testing, with a tensile strength reaching 5.82 MPa. Performance tests of the static cracking agent determined the optimal water-cement ratio of SCA and revealed the variation pattern of expansion stress over time, indicating that the maximum expansion stress of SCA can reach 75.9 MPa. SCA can effectively fracture the roadway surrounding rock.  
(2) For rock mass with 300 mm, 400 mm, and 500 mm hole spacings, the midpoint stress between drill holes in the rock mass can reach 5.12 MPa, 4.22 MPa, and 1.40 MPa; the initial fracturing stress around drill holes in the rock mass are 10.93 MPa, 14.52 MPa, and 21.81 MPa; and the complete breakage stresses of the rock mass are 21.58 MPa, 29.05 MPa, and 46.98 MPa, respectively. Generally, smaller hole spacing results in more cracks around the holes, leading to better fracturing effects.  
(3) For the engineering requirement of a 2.3 m high and 1.5 m deep roadway expansion, the technology parameters using SCA were obtained, as follows. Because a smaller hole spacing can lead to a better fracturing effect on the rock mass, a hole spacing of 300 mm is selected. Additionally, a 42 mm borehole diameter and a drilling depth of 1500 mm were determined based on the on-site construction conditions. Industrial test results showed that this static cracking technology can effectively fracture the roadway surrounding rock, facilitating the engineering construction of the roadway expansion.  
Conceptualization, R.Y., Z.L. and Q.Z.; formal analysis, R.Y., Z.L. and Q.Z. investigation, M.L., H.L. and Y.L.; writing--original draft, Q.Z., W.W., M.L., Z.L. and R.Y.; data curation, M.L., H.L. and Y.L.; writing--review and editing, R.Y., Z.L., Q.Z. and W.W.; funding acquisition, R.Y. and Q.Z. All authors have read and agreed to the published version of the manuscript.  
Figure 13: Roadway expansion effect.  
**Funding:** This research was funded by the National Natural Science Foundation of China, grant number 52174109; the Program for Innovative Research Team (in Science and Technology) in University of Henan Province, grant number 22 IRTSTHN005; the Key Research and Development Project of Henan Province, grant number 232102321130; the Key Research Project of Institutions of Higher Education in Henan Province, grant number 24A580001; and the National Natural Science Foundation of Henan Province, grant number 232300420303.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Data are contained within the article.  
**Conflicts of Interest:** The authors declare no conflicts of interest.