There are a number of engineering situations where fluid-saturated geological media can be subjected to thermal effects. These include the disposal of heat-emitting nuclear fuel wastes in saturated geological formations, extraction of energy resources such as oil and natural gas by steam injection and the recovery of geothermal energy by ground source heat exchangers. The objective of this thesis is to study the coupled thermal-hydrological-mechanical (T-H-M) response of fractured geological media by the computational implementation of mathematical models. From the generalization of Biot's classical theory of consolidation of a saturated porous elastic medium to include thermal effects, we first derived the equations governing coupled T-H-M processes in saturated geological media. In order to obtain numerical solutions for the governing equations, the finite element method was used. A finite element computer code, FRACON (FRActured media CONsolidation), was developed in order to simulate plane strain and axisymmetric problems. Eight-noded isoparametric elements were developed to represent the intact regions of the geological medium, while special joint elements were developed to simulate discrete joints. The intact regions of the geological medium was assumed to exhibit linear elasticbehaviour. The joints between intact regions were modelled by constitutive relationships which reproduced both linear elastic and nonlinear elasto-plastic responses. The elasto-plastic stress-strain relationship of the joint, was formulated by appeal to classical theories of interface plasticity. The elasto-plastic model for joint behaviour thus formulated is capable of reproducing many of the fundamental features of mechanical behaviour associated with naturally occuring joints, such as dilation under shear and strain softening due to surface asperity degradation. Furthermore, the thesis presents a physically-based hydraulic model of the joint that permits the inclusion of the effec / The development of the FRACON code followed an extensive procedure of code verification via analytical solutions and intercode comparison. A unique set of benchmark problems was proposed in order to perform code verification for coupled T-H-M. / The FRACON code was used to interpret certain laboratory and field experiments, including the following: (1) coupled T-H-M laboratory experiment on a block of cementitious material; (2) lab experiments on joint shear behaviour under constant normal stress and constant normal stiffness conditions; (3) coupled shear-flow laboratory experiment on a joint; (4) Field experiments of fluid injection in a horizontal fracture in a granitic rock mass. / Lastly, the FRACON code was used to simulate the coupled T-H-M response of a rock mass to radiogenic heat from nuclear fuel wastes buried in the rock formation. The coupled H-M response of this rock mass to a future glaciation scenario was also simulated. It was shown that the mechanical/hydraulic regimes of the rock mass could be significantly changed by the above two factors. The importance of the consideration of T-H-M processes in the overall scheme of safety assessment of sites targeted for nuclear fuel waste repositories is supported by the findings of this thesis.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.29096 |
| Date | January 1995 |
| Creators | Nguyen, Thanh Son |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Civil Engineering and Applied Mechanics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001474161, proquestno: NN08139, Theses scanned by UMI/ProQuest. |
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