TWO-PARAMETER FROST-HEAVING MECHANICAL MODEL FOR TRAPEZOIDAL CANAL ON PASTERNAK FOUNDATION CONSIDERING DOUBLE SHEAR EFFECT UNDER OPEN SYSTEM CONDITION

Existing Winkler model cannot reflect the interaction between soil springs and needs to presuppose the distribution of tangential ad-freezing force. To overcome these shortcomings, two-parameter frost-heaving mechanical model is put forward for trapezoidal canal on Pasternak foundation considering double shear effect. Normal interaction between frozen soil and concrete lining is reflected in the model through introducing a shear layer. Tangential interaction between frozen soil and concrete lining is reflected in the model including contact interfacial layer. The frost heave displacements of lining plates are computed based on a trapezoidal canal in the Tarim irrigation area, serving as a prototype. The results obtained from the presented method, material mechanics method, and Winkler model are compared with the observed values through a comprehensive analysis. The findings suggest that the results obtained through the Pasternak method exhibit a higher level of conformity with observed values, as it takes into account the reduction in frost heave force resulting from frost-induced deformation and the interaction among Winkler soil springs. Furthermore, parameter analysis for tangential displacement of each point on concrete lining under different interface shearing stiffness k_x is carried out. The results show that, as k_x is smaller, tangential displacement of each point on interface tends to follow linear distribution, and tangential freezing force on interface also tends to follow linear distribution; as k_x is larger, tangential displacement of each point on interface deviates from linear distribution, and tangential freezing force on interface also deviates from linear distribution, so linear distribution hypothesis is no longer applicable under such condition. The model can more adequately describe the interaction between concrete lining and frozen soil on contact interface, and therefore the computational accuracy of the model is improved effectively.