冻融循环下隧道非冻土段底部融沉变形规律

为研究寒区隧道非冻土段在冻融循环条件下的底部融沉规律以及洞内不同的气温对隧道底部融沉变形的影响。利用温度场解析解确定非冻土段范围,采用有限元进行建模计算。计算结果显示:在冷空气作用下,原来处于非冻结状态的围岩开始发生冻结,并产生向上的冻胀位移,表层围岩的冻融位移最大,初期最大冻胀位移可达8 mm,随着洞内气温的周期性变化,底部围岩出现周期性的冻融,最大融沉位移逐年增加,第8年开始冻融变形达到稳定,最大融沉位移可达20.0 mm,冻胀位移则稳定在5 mm左右。总体来说,随着围岩温度周期性变化趋于稳定,其冻融位移的周期性变化也趋于稳定。在不同气温影响下,随着隧道进深的增加,隧道底部的最大冻胀位移和融沉位移均减小。

Deformation Rules of Thaw Settlement of Non-frost Section of Tunnel under Freezing-thawing Cycle

In order to study the rules of thaw settlement of non-frost section of cold region tunnel under freezing - thawing cycle and the effect of different temperature in the tunnel on the deformation of the thaw settlement of the tunnel, the temperature field analytical solution is used to determine the range of non-frost sections, and the finite element is used for modeling calculation. The calculation results show that under the action of cold air, the surrounding rock which is in the non-freezing state begins to freeze and produces upward frost heave displacement. The freezing and thawing displacement of the surrounding rock is the largest, and the initial maximum frost heave displacement can reach up to 8.0 mm. The periodic variation of temperature in the cave, periodic freezing and thawing of the surrounding rock, the maximum thaw settlement displacement increases year by year, the freezing and thawing deformation becomes stable in the 8th year, the maximum thaw settlement displacement can reach to 20.0 mm, and the frost heave expansion displacement is stable at around 5 mm. In general, as the periodic variation of surrounding rock temperature tends to be stable, the periodic variation of its freeze-thaw displacement tends to be stable. Under the influence of different air temperature, with the increase of tunnel depth, the maximum frost heave displacement and the thaw settlement displacement at the bottom of the tunnel are reduced.