High capacity tensiometers (HCT) are sensors used in geotechnical engineering to monitor positive and negative porewater pressures (soil suction) up to 2MPa in soil infrastructures and for the study of unsaturated soils in the laboratory. The proposed research aims to develop Ultra High Capacity Tensiometers (UHCT) that can measure soil suctions in the range of 7-10MPa with the intent of overcoming existing limitations with high capacity tensiometers (HCT) namely, measuring range and cavitation.
HCTs are normally composed by a ceramic filter with an air entry value (AEV), pressure transducer and water reservoir encased in a protective sheath. The measuring range of HCTs is constrained by the AEV of the ceramic filter, more precisely on the largest pore within the ceramic filter. The major limitation of HCTs, however, is cavitation occurring as the result of tension breakdown within the water reservoir when water is under tension. Which can also occur at lower values than 2MPa when used in prolonged monitoring in-situ. While cavitation cannot be avoided, it is believed that by increasing the measuring range cavitation can be delayed and as direct result extending the monitoring capability of HCTs. Furthermore, by increasing the measuring range of HCTs, detailed studies on the water retention behaviour of unsaturated soils becomes possible.
Therefore, as part of the development of UHCTs, new ceramic filters with specific pore sizes are require to be developed in-house. UHCTs built with the new ceramics will then be assessed in relation to measuring range and long-term measurement with the intent to develop future proof soil suction monitoring systems and for comprehensive studies of the water retention behaviour in unsaturated soils.
Applicants with degrees in Civil Engineering, Materials Science/Engineering, or a related subject are encouraged to apply. Knowledge of fundamental soil mechanics and geotechnical laboratory and field experience is highly desirable.
This project is supervised by Dr Joao Mendes.
Please note eligibility requirement:
• Academic excellence of the proposed student i.e. 2:1 (or equivalent GPA from non-UK universities [preference for 1st class honours]); or a Masters (preference for Merit or above); or APEL evidence of substantial practitioner achievement.
• Appropriate IELTS score, if required.
For further details of how to apply, entry requirements and the application form, see https://www.northumbria.ac.uk/research/postgraduate-research-degrees/how-to-apply/
Please note: Applications that do not include a research proposal of approximately 1,000 words (not a copy of the advert), or that do not include the advert reference (e.g. SF19/EE/MCE/MENDES) will not be considered.
Start Date: 1 March 2020 or 1 October 2020
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Mendes J., Gallipoli D., Tarantino A., Toll D. On the development of an Ultra-High Capacity Tensiometer capable of measuring water tensions to 7 MPa. Geotechnique, 69(6), 2019.
Mendes J. and Buzzi O. New insight into cavitation mechanisms in high-capacity tensiometers based on high-speed photography. Canadian Geotechnical Journal. 50(5), 2013.