**4. Conclusions**

**0**

**8.59**

**(1 0.6 )**

**8.59 22.8 (1 0.6 )** *c*

−

 *v S* <sup>+</sup>

*Q*

*C D*

= −

*C D*

+

*v*

*c*

−

   *S*

*Q*

**150**

**300**

**450**

**20 % error bars**

**∆***T***m (K)**

**600**

**750**

*m*

*T*

**900**

**4. Conclusions** The model-scale tunnel calculates the maximum temperature increase in the smoke The model-scale tunnel calculates the maximum temperature increase in the smoke under the interconnected tunnel by combining the velocity and HRR of the fire source under various blockage ratios. The following are the key conclusions of this paper:

under the interconnected tunnel by combining the velocity and HRR of the fire source under various blockage ratios. The following are the key conclusions of this paper: (1) The velocity of the ramps upstream of the fire source and the adjacent ramp have (1) The velocity of the ramps upstream of the fire source and the adjacent ramp have an impact on the maximum temperature rise in the interconnected tunnel. The maximum temperature rise is jointly impacted by both ramps' ventilation.

an impact on the maximum temperature rise in the interconnected tunnel. The maximum temperature rise is jointly impacted by both ramps' ventilation. (2) The maximum temperature rise in the interconnected tunnel varies with velocity and the blockage ratio. Depending on who is more impacted by the velocity or blockage (2) The maximum temperature rise in the interconnected tunnel varies with velocity and the blockage ratio. Depending on who is more impacted by the velocity or blockage ratio, the maximum temperature rise differs. The maximum temperature rise decreases, and the impact of the blockage ratio diminishes when the velocity in the interconnected tunnel decreases. This is because the convective heat transfer near the fire source increases.

ratio, the maximum temperature rise differs. The maximum temperature rise decreases, and the impact of the blockage ratio diminishes when the velocity in the interconnected tunnel decreases. This is because the convective heat transfer near the fire source in-(3) In an underground interconnected tunnel fire, the maximum temperature rise is influenced by the velocity upstream of the fire source and the adjacent tunnel. As a result, this research provides a novel method for predicting the maximum temperature rise under the underground interconnected tunnel that is blocked by vehicles.

creases. (3) In an underground interconnected tunnel fire, the maximum temperature rise is influenced by the velocity upstream of the fire source and the adjacent tunnel. As a result, We only studied blockage rates between 0% and 30% in this paper. Additionally, the angles between ramp C and ramp D were not considered. More research will be carried out in the next stage.

this research provides a novel method for predicting the maximum temperature rise under the underground interconnected tunnel that is blocked by vehicles. We only studied blockage rates between 0% and 30% in this paper. Additionally, the **Author Contributions:** Methodology, Z.X.; software, J.Z.; validation, H.Y.; formal analysis, H.Y.; investigation, H.Y.; resources, B.X.; data curation, Y.Z.; writing—original draft preparation, Y.Z.; writing—review and editing, S.M.S.T. All authors have read and agreed to the published version of the manuscript.

angles between ramp C and ramp D were not considered. More research will be carried out in the next stage. **Funding:** The Science and Technology Research and Development Program Project of China railway group limited (Major Special Project, No.: 2021-Special-04-2) funded this research.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** We acknowledge the High-Performance Computing Center of Central South University for its support.

**Conflicts of Interest:** The authors declare no conflict of interest.
