UM E-Theses Collection (澳門大學電子學位論文庫)


Vertical drain consolidation of unsaturated soil by differential quadrature method

English Abstract

Consolidation in a vertical drain foundation is a common problem in foundation engineering. Compared with saturated soils, unsaturated soils consist of not only water phase, but also air phase. The excess pore-water and pore-air pressures simultaneously change during the consolidation procedure and the solutions are not easy to obtain. In this thesis, the differential quadrature method (DQM) is employed to analyze consolidation of unsaturated soils in a vertical drain foundation with or without smear effect. The radial seepage of sand drain foundation is considered based on the framework of Fredlund's one-dimensional consolidation theory in unsaturated soils. With the use of Darcy’s law and Fick’s law, the polar governing equations of excess pore-air and pore-water pressures of consolidation in vertical drain foundation are derived. By using DQM, the two governing equations are transformed into two sets of ordinary differential equations. Then the solutions of excess pore-water and pore-air pressures can be obtained by Rong-Kutta method. For the consolidation without smear effect, the DQ solution can be used to deal with the case of non-uniform initial pore-air and pore-water distributions. The II convergence analysis, the average degree of consolidation, the radial displacement and the vertical settlement, effects of different initial pore water/air pressures distributions and effects of different boundary conditions are presented to study the behavior of consolidation of unsaturated soils without smear effect in a vertical drain foundation. For the consolidation with smear effect, the soil layer is divided into three parts: vertical drain, disturbed zone and undisturbed zone. In disturbed zone, as the soil around vertical drain is disturbed by the installation of vertical drain, the permeability coefficients of water and air phases decrease in some of degree compared with that in undisturbed zone. Finally, the accuracy analysis, the effect of consolidation with different permeability of water phase, the effect of consolidation with different permeability of air phase, the effect of consolidation with different length of disturbed zone are also performed to illustrate consolidation behavior of the vertical drain under smear effect are presented and discussed in this thesis.

Issue date



Tu, Shuai


Faculty of Science and Technology


Department of Civil and Environmental Engineering




Soil consolidation

Soil mechanics

Soils -- Analysis

Soil moisture


Zhou, Wan Huan

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1/F Zone C
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