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Distribution and Simplified Calculation Method of the Frost Heaving Force of Highway Tunnels in Cold Regions
(1 Department of Geotechnical Engineering, Tongji University, Shanghai 200092;2 Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092;3 First Highway Survey and Design Institute, China Communications Construction Group, Xi′an 710075;4 Highway Planning, Survey and Design Institute of Yunnan Province, Kunming650011)
Abstract 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 forces 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 frost 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. Accordingly, 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 regions, as well as the frost heaving force loads on the Qingshashan Tunnel. The difference between the calculated value 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 characteristics. 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.
Abstract：
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 forces 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 frost 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. Accordingly, 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 regions, as well as the frost heaving force loads on the Qingshashan Tunnel. The difference between the calculated value 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 characteristics. 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.
HUANG Ji-Hui- 1,
2 Xia-Cai-Chu- 1,
2 Han-Chang-Ling- 3 Li-Zhi-Hou- 4
.Distribution and Simplified Calculation Method of the Frost Heaving Force of Highway Tunnels in Cold Regions[J] MODERN TUNNELLING TECHNOLOGY, 2016,V53(5): 63-70
2016, Vol. 53 