Experimental Study on Freezing Front Model of Alpine Tunnel under Wind Field

In order to study the freezing front characteristics of alpine tunnels under the condition of wind flow field and relying on the Osaka Mountain tunnel in Qinghai Province, the physical model test of an alpine tunnel was built. By using the Surfer software combined with the laboratory test data, the radial and longitudinal temperature variation trends of the tunnel were obtained, and the overall temperature vector graph of the tunnel was simulated; the radial and longitudinal evolutionary laws of a freezing front in an alpine tunnel under airflow conditions were systematically analyzed, and the radial and longitudinal governing equations of a freezing front in the tunnel model under airflow conditions were proposed. The results show that: With the decrease of the test air temperature, the thermonuclear area in the surrounding rock gradually shrinks, the frozen area of surrounding rock at the bottom of the arch gradually increases, and the frozen area of surrounding rock at the top of the arch gradually expands to the interior of the mountain. The influence degree of ventilation on the longitudinal and radial temperature distribution of the tunnel is obvious, and the greater the wind speed, the greater the influence degree. In particular, the fluctuation range of the longitudinal temperature distribution of the tunnel is more extensive under the influence of ventilation. The freezing front distance in the inverted arch area is the largest, and the expansion distance of the freezing front in the wall foot area is obviously higher than that in the vault; the variation of the longitudinal freezing front at different positions of the tunnel shows parabolic attenuation and with an increase in tunnel depth, the trend of freezing front gradually eases and becomes stable and disappears; the three radial regions of the freezing front and the longitudinal quadratic parabola governing equations can predict the specific distribution characteristics of the freezing front at different depths of the tunnel.