A Study on the Effect of External Parameters on Expansive Soils

Flood, Zack (2018) A Study on the Effect of External Parameters on Expansive Soils. [USQ Project]


An expansive soil has the potential to change volume under certain conditions such as a change in moisture level in the soil. These changes in moisture level in the soil cause either swelling or shrinkage depending on the moisture change. This distinctive behaviour of a clay-soil is referred to in the literature as reactivity. The movement caused by the expansive behaviour of these soils causes distress to the buildings and roads built upon them, effectively reducing the life of the structure or pavement.

Damages to such structures as a direct result of expansive soils has been reported in numerous countries around the world including Australia. The research within this study aims to further inform the literature concerning the effect of external parameters on expansive soils. The objective of this research project is to signify the importance of considering all factors affecting the situation, when designing on expansive soil.

This research project examines the swelling potential of two predominate soil types found within the Toowoomba area. The project involves sample collection including in-situ testing and sampling, initial soil characterisation tests, followed by a series of experimental tests to examine the swelling potential of the soil samples. The experimentation phase examines the effect of loading, compaction, initial moisture content and wetting rates on the swelling behaviour of each soil.

The main component of the experimentation is based on a one-dimensional swelling analysis using a CBR moulded specimen. This analysis consists of comparing a variety of cases with different aspects and parameters against the initial control points. The swell patterns are plotted against time to examine the differences in swelling rates between the different conditions and cases.

Analysis of the findings revealed that the accuracy of some key indicators such as the weighted plasticity index, used to predict the expansion potential of expansive soil, aren’t necessarily reflected in the physical behaviours of the soil. As a result of analysis and comparison between indicative and experimental tests, it was concluded that a greater emphasis should be placed upon the hydrometer analysis, as the reactivity was predominately influenced by the clay content of the soil type and its swelling potential.

Statistics for USQ ePrint 40676
Statistics for this ePrint Item
Item Type: USQ Project
Item Status: Live Archive
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 - 31 Dec 2021)
Supervisors: Wahalathantri, Buddhi
Qualification: Bachelor of Engineering (Honours) (Civil)
Date Deposited: 29 Aug 2022 05:38
Last Modified: 29 Jun 2023 01:32
Uncontrolled Keywords: expansive soil; moisture level; reactivity; external parameters
URI: https://sear.unisq.edu.au/id/eprint/40676

Actions (login required)

View Item Archive Repository Staff Only