青沙山隧道地温场测试与分析

采用埋入式铂金属热敏电阻测试方法,对地处青藏高原东部的青沙山公路隧道地温场进行现场实测与分析。结果表明:隧道洞口段,当环境温度较低时,地温差值分布明显,隧道进出口段衬砌背后出现相当长时间的负温;隧道洞内段,11月至次年3月,环境温度与所测地温相差很大,4月至7月,地温不稳定,围岩内各测点的温度曲线按位置重新进行调整,低温曲线上升到最高温处,高温的曲线则到达最低温处;7月至11月,隧道进口端地温下降曲线同隧道区环境温度变化同步,而隧道出口端地温比该处隧道内环境温度滞后;在冬季,衬砌内温度始终呈现倒U型,从隧道口向隧道中间,地温是上升的,地温上升呈现进口幅度小,出口幅度大,在低温度月份进口温度稍高于出口温度,在较高温月份进口温度低于出口温度;随着围岩深度的加深,温度是增加的,浅处的温度增量要大于深处;围岩内隧道径向存在某一比较稳定的温度边界条件。

In-Situ Test and Analysis of the Ground Temperature Field in Qingshashan Highway Tunnel

Embedded platinum metal thermistor method was adopted to carry through field tests and analyses on the temperature field of Qingshashan highway tunnel located in the east of Qinghai-Tibetan Plateau.Results show that when the ambient temperature was lower,the difference of ground temperature was obviously distributed at tunnel outlet and there was long-term negative temperature at the port of the tunnel behind the lining.In the inner tunnel,from November to March next year,there was great difference between the ambient temperature and the measured ground temperature.From April to July,ground temperature was not stable.Temperature curve of each measuring point inside the surrounding rock was re-adjusted according to location.Low temperature curve ascended to the uttermost high temperature point,while high temperature curve descended to the uttermost low temperature point.From July to November,the falling curve of ground temperature at the tunnel entrance was synchronous with the change of tunnel ambient temperature,whereas,the ground temperature at the tunnel exit lagged behind the ambient temperature in the tunnel.The temperature inside the lining presented an inverted-U type all along the whole winter.The ground temperature was ascending from tunnel outlet to the middle of tunnel.The rise extent in ground temperature was little at tunnel entrance and big at tunnel exit.During months with low temperature,the temperature at tunnel entrance was a little higher than that of tunnel exit.While during months with higher temperature,the temperature at tunnel entrance was lower than that of tunnel exit.The temperature rose with the depth increase of surrounding rock.The increase of temperature at the shallow was greater than that of the deep.There was a comparatively stable temperature boundary condition in the radial of tunnel inside the surrounding rock.Research results have provided reference for the study of temperature field and frostbite prevention as well as heat preservation for tunnel in cold regions.