Abstract: To investigate the smoke spread characteristics and the heat exhaust efficiency of shed tunnel structures under fire conditions in a tunnel-shed-tunnel configuration, this paper conducted numerical simulation studies. The effects of factors such as the opening mode, opening ratio, and shed length on smoke spread characteristics and heat exhaust efficiency were analyzed. The results show that there is a significant difference in heat exhaust efficiency between top-opening and side-opening shed structures. Under the side-opening shed structure, the opening ratio has a relatively small effect on heat exhaust efficiency, with the maximum efficiency reaching only 10%. As the shed length increases, the smoke exhaust performance improves, but the smoke concentration beneath the shed roof remains high. Under the top-opening shed structure, the opening ratio significantly affects the smoke exhaust capacity of the tunnel group, with heat exhaust efficiency reaching up to 85%. As the shed length increases, the smoke concentration at the top of the shed decreases. This study provides a scientific and rational basis for controlling tunnel group fires, reducing the loss and severity following such fires, and offers guidance for future tunnel construction.

Key words: tunnel fire, tunnel-shed-tunnel structure, shed tunnel opening ratio, shed tunnel opening configuration, smoke spread characteristics, heat dissipation efficiency