ELASTIC FROZEN SOIL FOUNDATION BEAM MODEL FOR TRAPEZOIDAL CANAL WITH CONSIDERATION OF COUPLED AXIAL-BENDING DEFORMATION

Elastic frozen soil foundation beam model, which can effectively describe the interaction and deformation compatibility between frozen soil and concrete-lined structure, is widely used in frost-heaving mechanical analysis of concrete lining canals. A frozen soil foundation beam model for trapezoidal canal was proposed in this paper, which considered coupled axial-bending deformation based on existing models and the Winkler hypothesis. The coupling equations were solved by using differentiator series method and Cardano’s formula. Compared with previous studies, the presented model offers greater flexibility in selecting boundary conditions with clear physical meaning. Additionally, both normal and tangential boundary conditions of lining plate ends can be simultaneously considered. The inconsistencies between the front and back models were resolved by introducing undetermined parameters, which enables simultaneous calculation of the normal frost-heaving & tangential displacements at interface, and the interaction force between plates. Taking a trapezoidal canal in Tarim irrigation area of Xinjiang as prototype, the normal displacement caused by frost heaving, tangential displacement at the contact surface, section bending moment and upper surface stress of concrete lining plates were calculated. The calculation and comparative analysis of normal frost-heaving displacement indicate that the overall variation trend of results calculated by the presented model, the model without consideration of horizontal-vertical coupling and finite element method is consistent. Moreover, the proposed model yields results closer to observed values than other models. The calculation of tangential displacement of the bottom plate demonstrates that the presented model effectively captures the asymmetric distribution of tangential displacement and freezing force caused by solar exposure difference between sunny and shady slopes. The estimated crack position of the concrete lining plate, based on the upper surface stress calculation of the slope plate, is in good agreement with the observed values in irrigation area.