Evaluation of coupled hydro-mechanical (H-M) behaviour of in situ shaft sealing components for used nuclear fuel
| dc.contributor.author | Kim, Chang Seok | |
| dc.contributor.examiningcommittee | Graham, James (Civil Engineering) Rajapakse, Athula (Electrical and Computer Engineering) Wong, Ron Chik-Kwong (Civil Engineering, University of Calgary) | en_US |
| dc.contributor.supervisor | Alfaro, Marolo (Civil Engineering) Blatz, James (Civil Engineering) | en_US |
| dc.date.accessioned | 2017-09-06T20:37:32Z | |
| dc.date.available | 2017-09-06T20:37:32Z | |
| dc.date.issued | 2017 | |
| dc.degree.discipline | Civil Engineering | en_US |
| dc.degree.level | Doctor of Philosophy (Ph.D.) | en_US |
| dc.description.abstract | A full-scale shaft seal that is a composite concrete-clay-concrete seal was installed at Canada’s Underground Research Laboratory (URL). This installation spans a major water-bearing fracture zone located at a depth of 275 m and is intended to isolate two hydrogeochemcial regimes. Coupled Hydro-Mechanical (H-M) constitutive models were developed to examine performance of the H-M behaviour of the shaft seal. H-M parameters of the shaft seal components were determined using laboratory test data. The numerical results were compared with field readings regarding water uptake and development of total pressure in the system. Numerical prediction shows that the hydration process of the clay seal is dominantly affected by the groundwater flow from FZ2. Overall, numerical prediction shows reasonably good agreement with field readings; however, it underestimates evolution of total stresses. The possible reason could be that radial groundwater flow toward the system was not considered in the simplified 2-D modelling. Prediction of swelling pressure of the unsaturated clay seal is discussed. The first model using crystalline and osmotic swelling mechanisms estimates a swelling pressure of 0.86 MPa, which is close to what is expected (0.8 MPa) in the field. Another model applying confined conditions estimates a swelling pressure of 0.41 MPa. This difference in swelling pressure prediction could be attributed to different microstructures developed under different confining conditions. The model predictions were then verified in terms of the water retention capacity of the clay seal and show reasonably good agreement with the measured data. Sensitivity analyses were conducted to assess effects of variations of H-M parameters on evolution of H-M behaviour of the clay seal. Several sets of hydraulic and Barcelona Basic Model (BBM) mechanical parameters of the clay seal were determined using available laboratory test data. The numerical results indicate that the behaviour of the clay seal is more sensitive to hydraulic parameters than BBM mechanical parameters. Different sets of H-M parameters were obtained from the same clay material. For this reason, sensitivity analysis of the parameters and validation of the predictions are required to improve the possibility to match field and modelled behaviour. | en_US |
| dc.description.note | October 2017 | en_US |
| dc.identifier.uri | http://hdl.handle.net/1993/32466 | |
| dc.language.iso | eng | en_US |
| dc.rights | open access | en_US |
| dc.subject | Shaft Seals, H-M behaviour, Swelling pressure, Suction | en_US |
| dc.title | Evaluation of coupled hydro-mechanical (H-M) behaviour of in situ shaft sealing components for used nuclear fuel | en_US |
| dc.type | doctoral thesis | en_US |