Abstract：
To investigate the natural ventilation characteristics of deep and large shafts in ultra-long tunnels at high altitudes, this study focused on No. 1-2 Shaft of the Tianshan Shengli Tunnel on the Urumqi-Yuli Highway. Fixed meteorological and wind speed monitoring stations were established at the shaft base and mouth to conduct longterm monitoring of wind speed, wind direction, air temperature, and atmospheric pressure. The relationships between natural wind parameters (wind speed, wind direction) and air temperature, air pressure under different seasonal and temperature conditions were analyzed. Using fluid dynamics and tunnel ventilation network theories, the primary factors influencing natural wind speed and direction in the shaft were calculated and analyzed. The results show that during the construction phase of the Tianshan Shengli Tunnel, No.1-2 shaft primarily exhibit an exhaust ventilation mode under natural ventilation conditions. The natural wind in the shaft is closely related to meteorological conditions inside and outside the tunnel. Abrupt temperature changes could reverse wind direction. In spring, summer, and autumn, natural wind speeds at the shaft mouth show an increasing trend, with higher frequency and amplitude of fluctuations. On a daily basis, natural wind speeds in different time periods exhibit varying positive or negative correlations with air temperature and pressure. The wind speed at the shaft mouth is more sensitive to temperature changes, with average wind speed higher than 3.32 m/s on cloudy days compared to sunny days. During spring and summer, the effective exhaust speed in the shafts fails to meet tunnel ventilation requirements for pollutant removal, suggesting the need for jet fans to assist ventilation during construction. In contrast, the effective exhaust speed in autumn is sufficient for pollutant removal, allowing for the shutdown of ventilation fans to conserve energy. The thermal potential difference inside and outside the tunnel plays a decisive role in change in wind speed and direction. When the tunnel temperature exceeds external temperatures, the directions of thermal potential difference and hyperstatic pressure difference are aligned, increasing the shaft exhaust wind speed. Moreover, when the temperature difference inside and outside the tunnel is greater, the thermal potential difference between the shaft base and shaft mouth, as well as the exhaust wind speed inside the shaft, are greater, and the natural ventilation effect is more significant.
CHEN Jianxun1 WANG Heqi1,
2 JIA Haiyang1 LIU Weiwei1 LUO Yanbin1 ZHAO Zhiqiang1 HUANG Dengxia2
.Testing and Analysis of Natural Ventilation in No. 1-2 Shaft in the Tianshan Shengli Tunnel[J] MODERN TUNNELLING TECHNOLOGY, 2024,V61(6): 219-23
2024, Vol. 61 