Abstract: In order to reveal the influence of shaft structure on natural ventilation of urban traffic tunnel, two types of shaft structures, the central vertical type and the lateral inclined type, are designed by using the tunnel model with the scale of 1:10, and the comparative tests are carried out. The longitudinal and vertical temperature and flue gas diffusion under two types of shaft structure were investigated. The results demonstrated that the longitudinal temperature and vertical temperature of the central vertical shaft tunnel are lower than the lateral inclined shaft, and the smoke control effect is better than that of the lateral inclined shaft tunnel. This originated from that the central vertical shaft has larger effective exhaust area and the energy of the flue gas decays faster in it. This conclusion could provide technical reference for the design and construction of similar projects.

Key words: urban traffic tunnel, natural ventilation, shaft structure;temperature distribution, exhaust characteristics