Field Test Study on Air Curtain Insulation System During Tunnel Construction in Cold Regions
When the temperature inside the tunnel is below 5℃,the hardening rate of concrete will slow down,thereby affecting the quality of the project.The Shangshan Tunnel under construction on the Beijing-Lanzhou High Speed Railway was took as a supporting project.Firstly,the temperature changes at the pouring point of concrete inside the tunnel were compared under three measures:building cold-proof doors,building cold-proof doors + heating furnaces,and building air curtain insulation systems through field test experiments.Then,numerical simulation was used to analyze the influence of the jet wind speed and jet temperature of the wind curtain machine on the temperature at the pouring point of concrete inside the tunnel.The results show that when the wind speed at the entrance of the tunnel is 3.21 m/s and the temperature is-12.68℃,the temperature at the concrete pouring point inside the tunnel begins to drop below 5℃ when building the cold-proof door.When the wind speed at the entrance of the tunnel is 5.36 m/s and the temperature is-19.13℃,the temperature at the concrete pouring point inside the tunnel begins to drop below 5℃ when building a cold-proof door and heating furnaces,and other measures must be taken in combination.When the maximum wind speed at the entrance of the tunnel is 4.56 m/s and the minimum temperature is-15.83℃,the temperature at the concrete pouring point inside the tunnel after building the air curtain insulation system is 7.36℃.Appropriately increasing the jet wind speed or jet temperature of the wind curtain machine can increase the temperature inside the tunnel.From the perspective of reducing system energy consumption,it is recommended to increase the jet wind speed of the wind curtain machine appropriately.
tunnel in cold regionshardening rate of concretefield testnumerical simulationconstruction periodcold-proof doorair curtain insulation system
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