# Numerical Simulation and Engineering Application of Temporary Stress Field in Coal Mine Roadway
## 7 Conclusions  
In summary, to ensure reliable support of the surrounding rock and the reasonable setting of the unsupported distance during parallel operations of excavation and permanent support, this work proposed a temporary support stress distribution model. The research found that as height increases, the temporary support force initially increases and then decreases. Additionally, the results indicated that in the direction of excavation, the temporary support force remains relatively stable within a distance of 3 m but drops sharply beyond this threshold. The study on the evolution of roof strain in unsupported areas reveals a strong linear relationship between the unsupported distance and the optimal temporary support force. Under the action of temporary support, the maximum unsupported distance is 3 m, which is approximately 33% higher than the maximum unsupported distance of 2 m under permanent support. The inflection point in roof strain with changes in the length of the temporary support area occurs at 18 m from the tunnel face; therefore, the length of the temporary support area should not exceed 15 m. The on-site monitoring data largely indicate that temporary support can indeed generate a support stress field in the unsupported areas. The successful application of the shield tunneling robot system practically confirms that the method of long-distance temporary support following excavation is feasible. Moreover, it enables the parallel operation of permanent support and excavation, resulting in an almost 40% increase in tunneling efficiency. This work demonstrated that the stability of the surrounding rock in unsupported areas is closely related to the temporary support force, support length, and unsupported distance. This work provided a basis for the selection and design of temporary support equipment, control of the temporary support force, and reasonable setting of the unsupported distance. The rapid tunneling system is a complex system composed of multiple elements such as humans, machines, and the environment. Therefore, future research should focus on further exploring and optimizing these factors to enhance the stability of the surrounding rock and increase tunneling efficiency.  
H.Z.: Writing--review and editing, data curation, investigation, visualization. H.M.: Formal analysis, data curation, conceptualization. C.W.: Writing--review and editing, data curation, funding acquisition. Q.M.: Conceptualization, methodology, formal analysis, funding acquisition. X.X.: Formal analysis, Data curation, funding acquisition. 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 numbers 52374161 and 52174150; the Key Technologies Research and Development Program of China, grant numbers 2023 YFC2907603; Key Research and Development Projects of Shaanxi Province, grant numbers 2023-LL-QY-03; Shaanxi Science and Technology Association, grant numbers 2023-JC-YB-331.  
Not applicable.  
Figure 12: On-site monitoring data. (**a**) Excavation distance monitoring. (**b**) Roof strain monitoring.  
Data Availability Statement: The data presented in this study are available upon request from the corresponding author.