A model for predicting the frost-heave effect of a pile embedded in the frozen soil

A model for predicting the frost-heave effect on a single pile embedded in the frozen soil is proposed in this study. In the model, the half-space saturated soil is considered to be composed of an overlying soil layer denoting the frozen layer and underlying layers denoting the unfrozen layers. In the absence of the pile, the free frost-heave strain is assumed to occur only in the overlying frozen layer. The total strain field of the layered soil is equal to the superposition of the free frost-heave strain and the disturbed strain due to the presence of the pile. According to the Muki's fictitious pile method, the pile and frozen soil are supposed to be compatible at the pile-soil interface and no slide hence occurs at the interface, which is accomplished by assuming the equivalence of the vertical strains of the fictitious pile and soil. Based on the Muki's method, the second kind of Fredholm integral equation for the pile is established using the aforementioned pile-soil compatibility condition and the fundamental solution for the layered saturated soil. The fundamental solution of the layered saturated soil is obtained by means of the reflection and transmission matrix (RTM) method. Numerical results obtained by the proposed model for the pile are consistent with existing numerical and experimental results, validating the proposed model. With the proposed model, parametric studies are conducted to examine the influence of the freezing depth of the soil on the axial force and vertical displacement of the pile as well as the tangential force acting on the pile and the pore pressure of the pile-side soil. Numerical results show that the frost-heave axial force, tangential force, vertical displacement and pore pressure are all increased with increasing freezing depth.