Abstract: The mechanical behavior of double composite linings of the Yellow-River-Crossing tunnel is analyzed by using 3-D non-linear finite element method when contacts between assembled segments of outer linings, and contacts between the inner and outer linings are considered. The above numerical calculation is compared with the 1:1 simulation test of two models with and without cushions between the inner and outer linings. The test process, inclusive of the segments assembling, layered earth filling, pretensioning of inner linings, and the applying of water pressure, is fully simulated. In the model without cushions, despite the fully-opened gap between the inner and outer linings, pretension loads upon the inner linings are partly transferred to the outer linings through steel bars, which is proved to be critical for joint load  bearing of the double linings ； whereas in the model with cushions, stresses of the outer linings increase slightly under the pretension and water pressure loads, revealing that the inner linings are subjected independently to these loads. The numerical values are close to test values in terms of the distortion, the stresses, and the gap between the inner and outer linings.

Key words:  South-to-North Water Diversion Project  ,  Yellow-River-Crossing tunnel  ,  double composite lining  ,   3-D finite element    , contact nonlinearity