Semi‐analytical solution for double‐layered elliptical cylindrical foundation model improved by prefabricated vertical drains

This work proposes a semi‐analytical solution for a double‐layered elliptical cylindrical soft foundation improved by prefabricated vertical drains. The governing equations, continuity conditions are boundary conditions in the elliptical cylindrical system are introduced first. The Laplace transform is employed to convert the time variable t in partial differential equations into the Laplace complex argument s . Based on the boundary condition and continuity condition, the solution in the frequency domain is derived. By using Abate's fixed Euler Algorithm, the solutions in the time domain are obtained. A finite element analysis is performed to demonstrate the accuracy of the proposed solution. Then, parametric studies reveal that soil permeability and soil compressibility have great influences on the second layer of soil in the elliptical cylindrical system, but relatively small effects on the first layer. Neglecting differences in the hydraulic conductivity and the coefficient of volume compressibility of multi‐layered soil in the elliptical cylindrical system could not predict the excess pore pressure in the second layer correctly.