An Equal-Strain Analytical Solution for the Radial Consolidation of Unsaturated Soils by Vertical Drains considering Drain Resistance

Feng Zhou,Xudong Wang,Zheng Chen

doi:10.1155/2018/5069159

Feng Zhou, Xudong Wang + Show 1 more

Open Access

https://doi.org/10.1155/2018/5069159

Copy DOI

Abstract

Developing an analytical solution for the consolidation of unsaturated soils remains a challenging task due to the complexity of coupled governing equations for air and water phases. This paper presents an equal-strain model for the radial consolidation of unsaturated soils by vertical drains, and the effect of drain resistance is also considered. Simplified governing equations are established, and an analytical solution to calculate the excess pore-air and pore-water pressures is derived by using the methods of matrix analysis and eigenfunction expansion. The average degrees of consolidation for air and water phases and the ground surface settlement are also given. The solutions of the equal-strain model are verified by comparing the proposed free-strain model with the equal-strain model, and reasonably good agreement is obtained. Moreover, parametric studies regarding the drain resistance effect are graphically presented.

Highlights

As a common phenomenon of civil engineering, consolidation is a process of decreasing soil volume when soil is subjected to an increased stress. Understanding of this phenomenon is vital to designs of soft soil foundations, pavements, and other engineering structures. erefore, Terzaghi [1] established a classical theory for the analysis of consolidation in saturated soft soil foundation, which is well known in geotechnical engineering
There is no reference about the equal-strain model in the research of unsaturated soft soils. e objective of this paper is to propose an equal-strain consolidation model to investigate the consolidation behavior of unsaturated soft soils
The difference of normalized settlement Sne between different air permeabilities ka is mainly observed before the plateau period. is is because the change of the radius of vertical drain influenced all period of consolidation process

Summary

Introduction

As a common phenomenon of civil engineering, consolidation is a process of decreasing soil volume when soil is subjected to an increased stress. Advances in Civil Engineering is not always singly layered For this reason, Shan [25] presented an analytical solution of unsaturated multilayered soil with typical boundary conditions. It is essential to expand the consolidation theory of unsaturated soft soils from one-dimensional vertical consolidation to radial consolidation For this purpose, Conte [26] developed a general formulation that can be advantageously used to analyze consolidation under plane-strain conditions. Ho et al [27] discussed the excess pore-air and pore-water pressure dissipations in the plane-strain consolidation of unsaturated soft soils using eigenfunction expansion and Laplace transform techniques. In the research of saturated soft soils, Barron [33] firstly proposed the consolidation model for vertical drains under free-strain and equal-strain models. Parametric studies regarding the drain resistance effect are presented in this paper

Problem Statements

Solution of the Problem

Findings

Analysis of Consolidation Behavior