Abstract: In order to explore the method of optimizing the ventilation of highway tunnel construction by using the thermal potential difference of inclined shaft and improve the safety of tunnel construction, this study took a construction gas tunnel in Zhongliangshan, Beibei District, Chongqing as an example, and adopted a combination of theoretical analysis and numerical simulation. Firstly, the influence of the temperature difference between the inside and outside of the tunnel and the thermal potential difference caused by the slope of the inclined shaft on the tunnel ventilation was analyzed, and the pressure difference caused by the thermal potential difference between summer and winter was calculated, and the flow trend of natural wind in the inclined shaft was analyzed accordingly. Subsequently, a numerical model of the tunnel was established to simulate the distribution of wind speed, wind direction, ventilation dead zone and gas concentration in the tunnel under different working conditions. The results show that the thermal potential difference has a significant effect on the ventilation performance in the tunnel. In summer, when the natural wind caused by the thermal potential difference conflicts with the wind direction of the jet fan, it will lead to the formation of a ventilation dead zone in the tunnel, reduce the ventilation efficiency, and is not conducive to the discharge of gas. On this basis, a ventilation optimization scheme combining the synergistic effect of natural wind and mechanical ventilation was proposed, which made full use of the thermal potential difference of inclined shafts for ventilation, and significantly improved the wind speed and ventilation efficiency. After
optimization, the wind speed of the inclined well increases with the increase of the thermal potential difference. At the same time, the overall average wind speed of the tunnel has also been improved, the volume of the ventilation dead zone has been greatly reduced, and the average gas concentration has been reduced, which has significantly improved the safety of the construction of the gas tunnel.

Key words: tunnel ventilation, thermal potential difference, numerical simulation, gas concentration, ventilation efficiency