关键词: 隧道工程, 冰碛地层, 冻融圈, 冻胀力, 原位测试

Abstract: In this study, the Que’er moutain tunnel in the project of No. 317 national highway was investigated, and the frost heaving force of the moraine stratum at the entrance of the tunnel was measured in-situ by the self-designed test method. Meanwhile, the thickness of the freeze-thaw circle and frost-heaving force in the cold region was obtained by combining the numerical simulation and the theoretical calculation. Based on the frost heaving stress measured inside and outside the lining structures, the axial force, the bending moment distribution, and variation law of lining structure were calculated and compared with the existing research results. The results show that moraine stratum in the cold region, as the regular seasonal frozen soil in the plateau, are significantly affected by low temperature, and the thickness of freeze-thaw circle is about 2 m under low temperature for 22 hours. The frost heaving pressure is 19.8?158.3 kPa by frost heaving force calculation, while it is 40?240 kPa from the in-situ measurement. Besides, the smallest frost heaving pressure is found at the arch foot, while the largest value is at the inverted arch. The changes and distribution rules of the stresses inside and outside the lining structures in the moraine stratum are complex and different under the freezing and thawing conditions. The axial force and bending moment of the lining in the frozen state are fan-shaped and butterfly-shaped distributions, respectively. Compared with related research results, the in-site testing method is more reasonable, and the results are more accurate.

Key words: tunnel engineering, moraine stratum, freeze-thaw circle, frost heaving pressure, in-situ measure