Abstract: For semi-filled and semi-excavated road sections on steep cross-slopes in mountainous areas, proposed is a new type subgrade structure that integrates multiple functions, including retaining, cantilevering, and support. Based on Winkler foundation beam theory and Coulomb earth pressure theory, an analytical calculation model and its static equilibrium equation are established for this structure in a double-layered soil foundation. The initial parameter method is employed to construct a solution matrix equation, enabling the derivation of analytical solutions for the internal forces and deformations of the structure. An interactive computing program implementing this analytical method is developed using Python and PyQt5. Multi-method analyses are conducted on a case study from a highway project. Analysis results show that the analytical method aligns closely with the finite element simulation of two-dimensional truss model using Midas GTS NX, with discrepancies of less than 0.3%, verifying the accuracy of the analytical formulas. Additionally, the results from finite element simulation of three-dimensional solid model using Abaqus also agree well with the analytical solutions, with an error of about 10%, demonstrating that the analytical model and its solutions are both reasonable and feasible. The differences between analytical solutions and solid finite element numerical solutions are mainly attributed to variations in the earth pressure distribution behind the piles and differences in the simulated interaction between the structure and soil, which warrant further investigations.