Analytical Solution for Consolidation of Composite Column–Reinforced Ground in Unsaturated Soils Including Smear Effect and Time-Varying Loading

Abstract

This study proposes an analytical solution for axisymmetric consolidation analysis of composite column–improved ground in unsaturated soils including smear effect and arbitrary time-varying loading, where the composite columns of the circular or rectangular cross section consist of an impervious core column and a pervious gravel shell. The governing equations for composite column–improved unsaturated ground are derived, and the analytical solution of excess pore pressures and ground settlement was obtained with the Fourier series expansion and the decoupling method. Two dissipation equations and special cases from the existing literature are used to prove the validity of the equations and solutions obtained in the present study. A parametric analysis was carried out to study the relationship between the consolidation features and the influencing factors, and the results showed that it is more effective to increase the compression modulus in reducing the ground settlement than to enlarge the area ratio of the impervious core column. For the composite columns of a rectangular cross section, a larger length-width ratio leads to a slower consolidation rate when the rectangular perimeter is the same. Moreover, the current solutions can be applied to consolidation analysis of unsaturated ground improved by composite columns, pervious columns, impervious columns, or prefabricated vertical drains, containing smear effect and arbitrary time-varying loading.