| 1. |
- Chen, Y., et al.
(author)
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A permeability evolution model for crystalline rocks subjected to coupled thermo-hydro-mechanical loading
- 2013
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In: Chinese Journal of Rock Mechanics and Engineering. - 1000-6915. ; 32:11, s. 2185-2195
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Journal article (peer-reviewed)abstract
- An anisotropic damage model was established for fluid-saturated crystalline rocks of low permeability in coupled thermo-hydro-mechanical (THM) loading conditions by using the micromechanical approach in the framework of thermodynamics. The proposed damage model accounts for the impacts of some important micromechanisms, such as the interstitial water pressure, normal stiffness recovery induced by compressed microcracks and sliding and shear dilatancy of closed microcracks, on the macromechanical properties of rocks under non-isothermal condition. On this basis, using various homogenization approaches, estimates were presented for the variations in effective permeability of cracked rocks induced by anisotropic damage propagation. The predictive limitations associated with the lower bound estimates for the effective permeability of damaged rocks were discussed; and a rigorous upper bound estimate was then presented to account for the influence of some important microstructural features, such as the connectivity and persistence of microcrack system, on the permeability variation. Existing laboratory tests on granite samples for damage-induced variation in permeability in triaxial condition and for uniaxial mechanical response after high-temperature thermal treatment, together with the in-situ measurements of excavation-induced damage zone and permeability variation in the surrounding rock of the TSX tunnel, were used to validate the proposed models.
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| 2. |
- Chen, Y., et al.
(author)
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Numerical model for fully coupled THM processes with multiphase flow and code validation
- 2009
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In: Chinese Journal of Rock Mechanics and Engineering. - 1000-6915. ; 28:4, s. 649-665
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Journal article (peer-reviewed)abstract
- A numerical model for fully coupled THM processes with multiphase flow in porous media was developed based on the momentum, mass and energy conservation laws of the continuum mechanics and the averaging approach of the mixture theory over a solid-liquid-gas three-phase system. To characterize multiphase THM coupling and to make the governing equations closed, complete and compatible, six processes and their coupling effects were considered, including stress-strain, water flow, gas flow, vapor flow, heat transport and porosity evolution processes. The physical phenomena such as phase transition, gas solubility in liquid, thermo-osmosis, moisture transfer and moisture swelling were modeled. As a result, the relative humidity of pore gas was defined on a sounder physical basis, avoiding the traditional definition as a negative exponential function of suction and absolute temperature. By selecting displacements, pore water pressure, pore gas pressure, pore vapor pressure, temperature and porosity as basic unknown variables, a finite element formulation was then established, and a three-dimensional computer code, THYME3D, was developed, with each node of 8 degrees of freedom. The bentonite THM Mock-up experiments performed by CEA were employed to validate the mathematical model and the software. The main coupling mechanisms involved in the experiments were satisfactorily simulated in the validation, and the effects of the governing equations, the constitutive relations and the parameters on the coupled THM processes were understood. The work developed enabled further in-depth research on fully coupled THM or THMC processes in porous media.
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| 3. |
- Jing, Lanru, et al.
(author)
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Main rock mechanics issues in geological disposal of radioactive wastes : Yanshilixue Yu Gongcheng Xuebao
- 2006
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In: Chinese Journal of Rock Mechanics and Engineering. - 1000-6915. ; 25:4, s. 833-841
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Journal article (peer-reviewed)abstract
- Geological disposal of radioactive wastes is a multi-disciplinary issue of importance for national interest. It stimulated many challenging scientific and technical issues, and at a higher level, presented a series of demanding requirements for a country's overall research and development programme, its implementation and engineering practice, about basic policies and legislature concerning nuclear energy, defense, waste management and environment. Rock mechanics and rock engineering are very important fields for geological disposal of radioactive wastes, and contribute significantly to the conceptual design, site investigation, engineering design and construction, operation and the long-term safety assessment of the waste repositories. It plays, therefore, a irreplaceable role in the research and development programme of geological disposal of radioactive wastes. In this paper, we first summarizes briefly the main steps about repository system, followed by the major demands for rock mechanics and rock engineering during feasibility study and site investigation, and the major international trends concerning these issues. The focus is placed on the coupled thermo-hydro-mechanical and chemical (THMC) processes and the current status of research in international communities. At the end, the progresses in research and development works in the field of radioactive waste disposal in China are presented; and possible future working directions are discussed.
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