列车气动效应作用下隧道衬砌混凝土水分传输理论研究

Theoretical study on moisture transfer in tunnel lining concrete under train aerodynamic effect

针对高速列车气动效应在铁路隧道衬砌混凝土表面产生的高速气流和空气低压作用,提出考虑列车气动效应的隧道衬砌混凝土水分传输和湿度场理论计算模型,并对气体流速和表面低压等关键影响因素进行分析。研究结果表明:高速气流加速混凝土表面水分交换速率并减薄水汽过渡层,表面低压作用降低环境中的水蒸气分压并增大混凝土表面与内部孔隙之间的压力梯度;混凝土表面风速越大、气压绝对值越低,其内部湿度下降越快;环境条件对混凝土湿度场的影响仅局限在混凝土表面一定范围内,环境风速和表面气压变化对混凝土内部湿度影响较小;在标准大气压条件下,当混凝土表面风速由5 m/s增大至15 m/s时,距离干燥面10 mm和30 mm处60 d龄期时相对湿度分别降低32.6%和3.9%;在环境风速为0 m/s条件下,当混凝土表面气压由80 kPa降低至50 kPa时,距离干燥面10 mm和30 mm处60 d龄期时混凝土相对湿度分别降低37.9%和3.8%。本文所提出的理论模型可较准确地描述上述因素对混凝土湿度变化的加速效应。

In view of the high-speed air flow and low air pressure produced by the aerodynamic effect of high-speed train on the surface of tunnel lining concrete,a theoretical calculation model of water transmission and humidity field of tunnel lining concrete considering the aerodynamic effect was proposed.The key influencing factors such as gas velocity and surface air pressure were also analyzed.The results show that the high-speed air flow will accelerate the water exchange rate on the concrete surface and reduce the water vapor transition layer.The low air pressure will reduce the partial pressure of water vapor in the environment and increase the pressure gradient between the concrete surface and internal pores.The greater the surface wind speed and the lower the air pressure,the faster the internal humidity decreases.The effect of the environment conditions on the humidity of concrete is only limited to a certain region near the drying surface.The change of wind speed and air pressure has little effect on the internal humidity of concrete.Under the condition of standard atmospheric pressure,when the wind speed increases from 5 m/s to 15 m/s on the concrete surface,the relative humidity at 10 mm and 30 mm from the surface decreases by 32.6%and 3.9%,respectively.Under the condition of ambient wind speed of 0 m/s,when the air pressure on the concrete surface decreases from 80 kPa to 50 kPa,the relative humidity of concrete at 10 mm and 30 mm decreases by 37.9%and 3.8%at the age of 60 d,respectively.The proposed theoretical model can better describe the acceleration effect of the above factors on the change of concrete humidity.