Studying the effects of non-uniform stress distributions on soil heave

Petersen, David (2016) Studying the effects of non-uniform stress distributions on soil heave. [USQ Project]

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Abstract

Soil movement is a leading cause of structural damage annually globally and is constantly rising. The main cause of this movement is through swell from reactive soils by changes in moisture content. All soils experience a volume change when subjected to moisture changes, the severity of these volume changes depends on many factors relative to the soil. The severity of these changes
are most commonly measured using Atterberg limits and the plastic index but this only gives a magnitude of possible swell and alone is not a reliable indicator as it can produce false negatives.

More reliable tests for swell are generally more involved with time and resources and this increases if predictions of swell for site conditions are required. Most of these methods also make a number of assumptions and simplifications but also generally fail to accurately predict actual soil swells. Accuracy can generally be improved by increasing the number of tests therefore decreasing some assumptions and generalisations but in practice this is difficult to do. For this reason most research and development in this area has focused on testing a wider range of soils and comparing to known correlations or applying easily tested parameters to simplified swell models but no significant gain in prediction accuracy has been achieved in over 30 years.

This study explores the behaviour of soil swell when lateral stain and movement of soil is not restrained aver a non-uniform stress distribution. Behaviour, parameters and predic- tions from these test are compared with those from standard swell overburden oedometer testing. It was found that the swell behaviour of the soil under a load that has unre- strained lateral movement from under a loaded area to an unloaded area was significantly different to those experience in oedometer and triaxial testing. Significant focus is placed on the movement of soil from under the loaded area and the problems this may cause with current prediction models.

From the results obtained in this study it is possible that at least under certain condition soil does not exhibit behaviour that current prediction models are based upon and the assumptions they use. Recommendation of further study into changes in soil behaviour under a range of different conditions is made. More research efforts should be made on complex modelling of soil movement especially in areas of high damage rates for simulation purposes and design improvements.


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Item Type: USQ Project
Item Status: Live Archive
Additional Information: Bachelor of Engineering (Honours) Major Civil Engineering project
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying
Supervisors: Ghabraie, Kazem
Date Deposited: 21 Jul 2017 03:39
Last Modified: 21 Jul 2017 03:39
Uncontrolled Keywords: structural damage; soil movement; lateral stain; non-uniform stress distributions
Fields of Research : 09 Engineering > 0905 Civil Engineering > 090502 Construction Engineering
URI: http://eprints.usq.edu.au/id/eprint/31458

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