Swell properties of desiccated Regina clay

Damage to structures founded on the lacustrine areas is common in western Canada. Adverse volume change exist in both fully saturated and partially saturated soils. However, their behaviour is still not com­pletely understood. The purpose of this study is to investigate the volume change behaviour...

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Main Author: Lu, Yi-ming
Other Authors: Fredlund, Delwyn G.
Format: Others
Language:en
Published: University of Saskatchewan 2008
Online Access:http://library.usask.ca/theses/available/etd-10312008-114027/
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spelling ndltd-USASK-oai-usask.ca-etd-10312008-1140272013-01-08T16:33:34Z Swell properties of desiccated Regina clay Lu, Yi-ming Damage to structures founded on the lacustrine areas is common in western Canada. Adverse volume change exist in both fully saturated and partially saturated soils. However, their behaviour is still not com­pletely understood. The purpose of this study is to investigate the volume change behaviour and swell potential of remolded and desiccated Regina clay. <p> Three series of Constant-Volume and Free-Swell consolidation tests were performed to observe the effects of back pressure on the compression and rebound curves and the difference in the rebound behaviour in the two types of tests. Also determined was the relationship between initial water content and swelling pressure, and degree of saturation and χ value. Pore pressure measurements were also made during the tests.<p> It is found that back pressure does not significantly alter the rebound slopes of remolded, desiccated samples for degrees of saturation in excess of 90 percent; however, there is an upward shift of the compression-rebound curves. The rate of volume change is found to decrease with applied back pressure and this is believed related to the presence of air in the sample.<p> The presence of air in the soil and measuring system decreases pore pressure responses considerably. The application of back pressure increases the accuracy in measuring pore pressures and gives an experimental settlement­-log time curve which checks more closely with its theoretical curve. <p> The measured swelling pressures appear consistent with those measured by Noble on Regina clay. χ values, computed from the swelling pressure and soil suction, show a very rapid decrease with a decrease in degree of saturation. <p> Comparison of results from Free-Swell and Constant-Volume tests show a higher swelling pressure and rate of volume increase for the Free-Swell test. The slopes of the rebound curves are essentially the same for both types of tests.<p> For further confirming the effects of back pressure on volume change characteristics, future research should be carried out on samples with lower degrees of saturation. Samples prepared by static compaction would be satisfactory for such a study. It is also recommended that stress paths be taken into consideration in volume change investigations for partially saturated solls. Fredlund, Delwyn G. University of Saskatchewan 2008-11-03 text application/pdf http://library.usask.ca/theses/available/etd-10312008-114027/ http://library.usask.ca/theses/available/etd-10312008-114027/ en unrestricted I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.
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language en
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description Damage to structures founded on the lacustrine areas is common in western Canada. Adverse volume change exist in both fully saturated and partially saturated soils. However, their behaviour is still not com­pletely understood. The purpose of this study is to investigate the volume change behaviour and swell potential of remolded and desiccated Regina clay. <p> Three series of Constant-Volume and Free-Swell consolidation tests were performed to observe the effects of back pressure on the compression and rebound curves and the difference in the rebound behaviour in the two types of tests. Also determined was the relationship between initial water content and swelling pressure, and degree of saturation and χ value. Pore pressure measurements were also made during the tests.<p> It is found that back pressure does not significantly alter the rebound slopes of remolded, desiccated samples for degrees of saturation in excess of 90 percent; however, there is an upward shift of the compression-rebound curves. The rate of volume change is found to decrease with applied back pressure and this is believed related to the presence of air in the sample.<p> The presence of air in the soil and measuring system decreases pore pressure responses considerably. The application of back pressure increases the accuracy in measuring pore pressures and gives an experimental settlement­-log time curve which checks more closely with its theoretical curve. <p> The measured swelling pressures appear consistent with those measured by Noble on Regina clay. χ values, computed from the swelling pressure and soil suction, show a very rapid decrease with a decrease in degree of saturation. <p> Comparison of results from Free-Swell and Constant-Volume tests show a higher swelling pressure and rate of volume increase for the Free-Swell test. The slopes of the rebound curves are essentially the same for both types of tests.<p> For further confirming the effects of back pressure on volume change characteristics, future research should be carried out on samples with lower degrees of saturation. Samples prepared by static compaction would be satisfactory for such a study. It is also recommended that stress paths be taken into consideration in volume change investigations for partially saturated solls.
author2 Fredlund, Delwyn G.
author_facet Fredlund, Delwyn G.
Lu, Yi-ming
author Lu, Yi-ming
spellingShingle Lu, Yi-ming
Swell properties of desiccated Regina clay
author_sort Lu, Yi-ming
title Swell properties of desiccated Regina clay
title_short Swell properties of desiccated Regina clay
title_full Swell properties of desiccated Regina clay
title_fullStr Swell properties of desiccated Regina clay
title_full_unstemmed Swell properties of desiccated Regina clay
title_sort swell properties of desiccated regina clay
publisher University of Saskatchewan
publishDate 2008
url http://library.usask.ca/theses/available/etd-10312008-114027/
work_keys_str_mv AT luyiming swellpropertiesofdesiccatedreginaclay
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