高海拔特长隧道低温大风环境及对围岩-结构温度场的影响

为探明高海拔特长隧道洞外低温大风的成因、特征及对洞内风场、围岩-结构温度温度场的影响，以国道317线雀儿山隧道为工程依托，采用气象站、手持风速仪、红外测温仪、埋入式多点铂电阻温度传感器等，对冬季隧道贯通前后进出口两端隧址区、洞内净空风速、风向、温度以及隧道轴向、径向的围岩-结构温度场进行现场实测，分析低温大风成因和特征、隧道贯通前后负温区范围、风速风向变化规律以及对洞口段和洞深部围岩-结构温度场的影响。研究结果表明：受高原大尺度大气环流产生的高原季风以及雀儿山两侧日照时间、地形引起的小尺度范围内自由大气热力差影响，隧址区冬季风速高、温度低；大风时段主要集中在14：00~21：00，平均风速达10 m·s^-1，负温时段主要在19：00~8：30，隧道进、出口日最大气温差分别为23.5℃和28℃；隧道贯通前，进出口两端负温区段在860 m以内；贯通后，出口端主洞和平导负温区段为1 200，1 280 m，分别比进口端长了340，420 m；贯通前后，隧道深部最低风速分别为1.1，2.2 m·s^-1，洞内风向由两端向洞内方向转化为主要由出口向进口方向；隧道洞口浅埋段围岩和衬砌结构径向负温范围在贯通前为1.20 m，贯通后为0.80 m，且在上述范围内温度变幅较大；低温大风对隧道深部的围岩温度影响不大，但对结构表面温度影响明显，由于变温区主要集中在二衬混凝土结构内部，因此要重视结构内部产生的冻胀作用。

Strong Cold Wind Environment Outside Extra-long Tunnel in High-altitude Region and Its Influence on Temperature Field of Surrounding Rock Structure

To determine the causes and characteristics of strong cold wind outside extra-long tunnels at high altitudes, as well as its influence on the wind field and temperature field of the surrounding rock and structure inside the tunnel, the Que'ershan Tunnel in China National Highway 317 was examined in this study. The wind velocity, wind direction, and temperature outside and inside the tunnel as well as the temperature of the surrounding rock and structure along the axis and in the radial direction of the tunnel were field-tested using various measuring systems and devices, such as the meteorological station, hand anemometer, infrared radiation thermometer, and embedded multipoint platinum resistance temperature sensor. Finally, the causes and characteristics of strong cold wind, the range of negative temperatures, the change regularity of wind velocity and wind direction before and after tunnel breakthrough, and the influence on the temperature field of the surrounding rock structure at both ends and at the center of the tunnel were statistically analyzed. The results show that:the wind speed is higher and the temperature is lowest in winter. There are two main reasons for this:one is the plateau monsoon generated by large-scale atmospheric circulation over the plateau, and the other is wind caused by the thermal difference in the free atmosphere in small scale that is affected by the duration of sunshine and the terrain on both sides of the Que'er Mountain. The strong wind period is mainly from 14:00 to 21:00 every day, wherein the average wind speed reaches up to 10 m·s^-1. The lowest temperature period is mainly from 19:00 to 8:30, in which the daily maximum temperature differences are 23.5℃ and 28℃ at the entrance and exit, respectively. Before tunnel breakthrough, the range of negative temperatures at the entrance and exit was nearly 800 m; however, after tunnel breakthrough, the ranges at the main tunnel exit and parallel heading exit became 1 200 m and 1 280 m, nearly 300 m and 420 m longer than that at the tunnel portal, respectively. The wind direction in the tunnel was from both ends to the center before tunnel breakthrough; however, after tunnel breakthrough, it changed into the direction going from the exit to the entrance. Furthermore, from before to after tunnel breakthrough, the minimum wind speed at the center of the tunnel changed from 1.1 m·s^-1 to 2.2 m·s^-1. The range of negative temperatures in the radial direction of the surrounding rock and structure in the shallow buried section at the tunnel portal was 1.20 m and 0.80 m, respectively, and the temperature varied widely in the above range. At the center of the tunnel, the temperature of the surrounding rock was not affected by the strong cold wind. Nevertheless, the surface temperature field of the structure was obviously influenced. It should be noted that the frost heaving produced inside the structure is crucial because the temperature gradient is mainly concentrated in the concrete structure of the second lining.