Study on Tunnel Air Curtain Insulation System for Cold Areas

Abstract

With the growing number of tunnels in high-latitude and high-altitude areas, freezing damage is all the more obvious. In traditional insulation layer method, insulation layer is laid in the tunnel to prevent invasion of cold air by taking advantage of its low thermal conductivity. However, due to its narrow temperature adaptation range and high construction and maintenance costs, this method cannot completely solve the problem of tunnel freezing damage. To solve this problem, this paper proposes tunnel air curtain insulation system which can generate electricity using solar energy. Based on parameters such as indoor air temperature and wind velocity in the thermal insulation room, on the one hand, it intelligently controls running sets of air curtain, jet flow angle, and velocity, prevents invasion of the external cold temperature into the tunnel, so that the tunnel maintains an interior temperature above 0°C. On the other hand, it intelligently diagnoses air curtain machine to provide system fault warning, so that the system keeps safe and reliable operation. The results show that air curtain technology can effectively solve the problem of tunnel freezing damage in cold areas; multiple air curtains in series connection provide better barrier efficiency. From the measured data and calculation results of Lafashan tunnel, it can be seen that an air curtain is installed at the tunnel portal with jet speed of 22.7 m/s and temperature of 35.24°C, which can meet the tunnel without freezing damage when the external temperature is −10°C, and the external wind speed is 2 m/s, providing a new method for tunnel insulation technology in cold area.

Freezing Damage to Tunnels in Cold Regions and Weights of Influencing Factors

“…Therefore, the main influencing factors of tunnel freezing damage are summarized: groundwater, temperature, and surrounding rock properties. Moreover, the disaster factors of freezing damage are quantitatively evaluated by the analytic hierarchy process (AHP) [22,23].…”

“…This method has obvious limitations due to the influence of different geological conditions on different tunnel projects [8,[11][12][13][14][15][16][17][18]. (2) When analyzing the causes of freezing damage, these studies were mainly based on the existing engineering experience and lacked quantitative evaluation of the impact of various factors on the extent of freezing damage, which resulted in a significant limitation when they were used to guide the construction of other engineering projects [19][20][21][22][23][24]. Therefore, in tunnels in cold regions, the quantitative analysis of the factors and importance of inducing freezing damage should be paid attention to.…”

Model Test of Surrounding Rock Temperature Field under Different Drainage Structures and Insulation Conditions in High Cold Tunnel

“…Additionally, Wang proposed a fast construction method for insulation lining, which effectively suppresses icing and avoids frost damage. Gao et al (2022) suggested a tunnel air curtain insulation system that uses solar power generation [7]. This system intelligently controls the operation group, jet angle, and speed of the air curtain based on parameters such as indoor temperature and wind speed to prevent cold intrusion into the tunnel and maintain a temperature above 0 • C inside the tunnel.…”

“…Traditional leakage blocking and lining damage treatment techniques are no longer sufficient, and new research on drainage structures is necessary [12]. To address this issue, Zhou et al (2022) studied the optimization design of the central drainage ditch burial depth for highway tunnels in seasonal freezing areas through numerical simulation and established a transient heat transfer model involving heat conduction and phase change [13]. Zhu (2021) used MIDAS/GTS to model a tunnel in a cold region and determined the appropriate burial depth for the anti-freezing drainage tunnel based on the mechanical properties and deformation changes in tunnels in cold regions [14].…”