## 4 Conclusions  
A numerical model was established, and numerical simulations were carried out for the effect of the conditions of adding gas baffles to the top of the gas cabin of the utility tunnel on the diffusion of gas leaks and the propagation law of the explosion shock waves. A comparative analysis of the simulation results led to the following conclusions.  
(1) In the absence of ventilation, methane leaks and accumulates on top of the gas cabin. As the amount of leakage increases, methane will travel along the roof of the gas cabin toward both sides of the leak hole. The baffle can limit the propagation of methane on the top of the gas cabin and slow down the diffusion velocity of the gas, thus increasing the concentration of methane near the gas baffle and speeding up the time for the monitor to reach the alarm concentration. Under normal ventilation, the gas baffle does not block methane discharge. The safety zone formed on the leeward side of the gas baffle indirectly accelerates methane discharge. After the height of the gas baffle has reached 500 mm, further increases in height do not significantly advance the alarm time. Taking into account the setting of the separator and the requirements of the exhaust air, it is recommended that the height of the gas baffle should be set at no greater than 500 mm.  
(2) When the gas cabin is installed with the gas baffle, the first and secondary pressure peaks generated in the middle are smaller than those without the gas baffle. The gas baffle has the function of blocking the propagation of shock waves. However, due to the  
Figure 14: Overpressure-time curves of top of gas cabin with different gas baffle spacing.  
installation of the gas baffle, the superposition of the shock wave will make the pressure surge at the gas baffle. By comparing the simulation results of pressure change at the top of the gas cabin under different conditions with different gas baffle spacings, a distance of 50 m is recommended.  
(3) Overall, the gas baffle has a certain effect on improving the efficiency of leak monitoring and inhibiting the propagation of explosion shock waves. The greater the horizontal distance between the leak hole and the downstream monitor, the more obvious the improvement in monitoring efficiency, and the smaller the peak overpressure at the top baffle of the gas cabin will be. Combined with the simulation results, it is recommended that the air baffle spacing is not less than 50 m and the height setting is not greater than 0.5 m.  
Conceptualisation, W.Z. and B.G.; methodology, W.Z. and B.G.; software, W.Z., S.S. and C.R.; validation, W.Z., B.G. and C.R.; formal analysis, B.G. and C.G.; investigation, W.Z. and C.R.; resources, B.G.; writing--original draft preparation, W.Z.; writing--review and editing, B.G., C.R. and S.S. All authors have read and agreed to the published version of the manuscript.  
This research is supported by the \"Strategic Consulting Research Project of Henan Research Institute of China Engineering Science and Technology Development Strategy (2023 HENZDB 05)\", the \"NSFC- Shanxi Coal-based Low-Carbon Joint Fund Key Project (U1810203)\" and the \"Key R&D and promotion projects in Henan Province: (212102310013)\" and the \"Science and Technology R&D Plan Joint Fund in Henan Province (222103810098)\".  
Not applicable.  
The authors declare no conflict of interest.