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Experimental investigation on the impact of temperature during creep and stress relaxation behaviour of London clay
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Sheridan, Bradley James (2022) Experimental investigation on the impact of temperature during creep and stress relaxation behaviour of London clay. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3910200~S15
Abstract
The ever-growing climate problem has created a drive to ensure a sustainable future can be achieved by meeting the net zero carbon emissions requirement by 2050. Within the UK there has been an increase in record temperatures being experienced particularly since the turn of the millennium. The UK is now experiencing temperatures which are rising above 40°C and are set to continue over the next century. Therefore, it is crucial to understand why thermo-mechanical behaviour of clays is understood, as the increase in temperature causes an increase number of geomechanical problems. In addition, the temperature fluctuations surrounding energy geo-structures (ground source heating & thermo-piles) must be understood.
The study aims to assess the impact of temperature, ranging between 20 and 55 °C, on the time- and rate-dependent behaviour of London Clay. As the London clay unit lies within the warmest part of the UK and within a high urban development, it is vital we understand the impact temperature can play on this geological unit.
The thesis reports an extensive experimental program on the primary and secondary consolidation, stress relaxation, and rate-dependency. A series of conventional multi-staged loading (MSL) oedometer tests, and temperature-controlled constant rate of strain (CRS) oedometer tests were carried out on saturated and unsaturated reconstituted London clay (unit B) specimens, collected from the Bank Station project upgrade in London, UK.
The results demonstrate that temperature and suction play a pivotal role in the time- and rate-dependent behaviour of the reconstituted Bank Station London clay specimens. The main findings from the experimental program are as follows;
• An increase in temperature results in a linear decrease in apparent pre-consolidation stress (σp) values and in an increase in secondary consolidation (Cαe) and Cαe/Cc values, especially at higher stresses. The compression index (Cc) and swelling index (Cs) parameters are less sensitive to temperature variations.
• A coupled effect of temperature and strain rate on 1D compression response was identified. At a constant temperature, the higher the strain rate, the higher the σp. Similarly, at a constant strain rate, the higher the temperature, the lower the σp.
• The dependence on stress, temperature and suction observed in the Bank Station London clay specimens rejects the hypothesis of a constant α assumed by Mesri et al. (1994).
• The coefficient of stress relaxation (Rα) values appears to be temperature- and strain rate-dependent. Furthermore, the study demonstrates that the Rα = α relationship can be applied to the set of vertical stress and temperature appraised in the present work.
Item Type: | Thesis (PhD) | ||||
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Subjects: | S Agriculture > S Agriculture (General) | ||||
Library of Congress Subject Headings (LCSH): | Clay soils -- England -- London, Clay soils -- England -- London -- Thermomechanical properties, Clay soils -- Thermomechanical properties, Clay soils -- England -- London -- Creep, Clay soils -- Creep, Climactic changes -- England -- London | ||||
Official Date: | June 2022 | ||||
Dates: |
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Institution: | University of Warwick | ||||
Theses Department: | Institute for the Science of Cities | ||||
Thesis Type: | PhD | ||||
Publication Status: | Unpublished | ||||
Supervisor(s)/Advisor: | Rezania, Mohammad | ||||
Sponsors: | Engineering and Physical Sciences Research Council | ||||
Format of File: | |||||
Extent: | xii, 144 pages : illustrations (some colour) | ||||
Language: | eng |
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