Abstract:

Based on the consolidation theory of unsaturated soils proposed by Fredlund and his co-workers (1984), by using Fourier series expansion and Laplace transform technique, semi-analytical solutions are proposed for the axisymmetric consolidation of the unsaturated foundation under the piece-wise cyclic load with the equal strain hypothesis in this paper. Firstly, based on the radial boundary conditions and equal strain hypothesis, the governing equations of axisymmetric unsaturated soil consolidation under piece-wise cyclic load are established. Afterward, the governing equations are solved by applying series expansion and Laplace transform, and the semi-analytical solutions of excess pore-air and pore-water pressures and the average degree of consolidation are given. Then, the correctness of the solutions and their results is verified by the degradation method and finite difference method. Finally, three specific segmental cyclic loads are introduced as the typical cases, the consolidation properties of unsaturated soil ground with the change of permeability coefficient ratio (k_a /k_w), model size (N), and load characteristic parameter (a) are analyzed. The conclusions drawn in this paper can give a strong theoretical support for the treatment of unsaturated soil ground.

Key words: unsaturated soils, axisymmetric consolidation, equal strain hypothesis, piece-wise cyclic loading, semi-analytical solution