寒区公路隧道冻胀力荷载的分布形式和简化计算方法

Distribution and Simplified Calculation Method of the Frost Heaving Force of Highway Tunnels in Cold Regions

考虑同岩不均匀冻胀特性，文章采用数值法建模计算了不同冻土区曲墙式隧道的冻胀力，分析了埋深、衬砌形状对冻胀力量值的影响。结果表明：曲墙式隧道冻胀力包络图呈梨形，衬砌拱脚处的冻胀力最大，仰拱处的冻胀力最小；衬砌所受冻胀力随埋深增大而增大，季节冻土区工程冻土段和多年冻土区多年冻土段隧道埋深大于50m以及多年冻土区工程冻土段隧道埋深大于100m时，衬砌所受冻胀力随埋深增大基本保持不变。不同冻土区、相同级别同岩中，曲墙式衬砌和圆形衬砌所受冻胀力的比值为定值。据此对圆形隧道冻胀力解析解进行改进，得到了不同冻土区隧道冻胀力荷载的分布形式及简化计算方法，并计算了青沙山隧道的冻胀力荷载。冻胀力最大值计算结果与实测值的偏差在16％-33％之间，计算冻胀力包络曲线与实测情况在量值和分布特征上吻合良好。该方法不需要进行建模，比数值方法更加快捷，又考虑了埋深、衬砌形状对冻胀力的影响，弥补了解析解的不足，能够应用于寒区隧道冻胀力的计算，具有很强的实用性。

Considering the uneven frost heaving of surrounding rocks, calculations of frost heaving forces on curved-wall tunnels in different frost regions were carried out by FEM method and the impacts of tunnel depth and lining structure on frost heaving force values were analyzed. The results show that the envelope of frost heaving forc- es is pearl shaped, with the maximum force occurring at the arch spring and the minimum force at the inverted arch, and the frost heaving force on the lining increases with tunnel depth, while the frost heaving force basically remains unchanged when the depth of the tunnel in a seasonal fi＇ost region and permafrost region is more than 50 m or the depth of the tunnel in a permafrost region is more than 100 m. The ratio of frost heaving forces on the curved-wall lining and round lining is a constant regarding the same class surrounding rock in different frost regions. According- ly, the analytical solution for the frost heaving force on a round-shaped tunnel was modified and the distributions and simplified calculation methods were obtained for the frost heaving force loads of tunnels in different frost re- gions, as well as the frost heaving force loads on the Qingshashan Tunnel. The difference between the calculated val- ue and the measured value of the maximum frost heaving force is 16% to 33%, and the calculated frost heaving force envelop curve coincides quite well with the in-situ measurements in terms of magnitude and distribution characteris- tics. In conclusion, this method does not require modeling, is performed more quickly than the FEM method, consid- ers the impacts of depth and lining structure on frost heaving force and makes up the shortfall of analytical solutions, and is therefore very practical and can be used for calculating the frost heaving force on tunnels in cold regions.