| 1. |
- Chen, Y., et al.
(författare)
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A permeability evolution model for crystalline rocks subjected to coupled thermo-hydro-mechanical loading
- 2013
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Ingår i: Chinese Journal of Rock Mechanics and Engineering. - 1000-6915. ; 32:11, s. 2185-2195
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Tidskriftsartikel (refereegranskat)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, Yifeng, et al.
(författare)
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Micromechanical Modeling of Anisotropic Damage-Induced Permeability Variation in Crystalline Rocks
- 2014
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Ingår i: Rock Mechanics and Rock Engineering. - : Springer Science and Business Media LLC. - 0723-2632 .- 1434-453X. ; 47:5, s. 1775-1791
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a study on the initiation and progress of anisotropic damage and its impact on the permeability variation of crystalline rocks of low porosity. This work was based on an existing micromechanical model considering the frictional sliding and dilatancy behaviors of microcracks and the recovery of degraded stiffness when the microcracks are closed. By virtue of an analytical ellipsoidal inclusion solution, lower bound estimates were formulated through a rigorous homogenization procedure for the damage-induced effective permeability of the microcracks-matrix system, and their predictive limitations were discussed with superconducting penny-shaped microcracks, in which the greatest lower bounds were obtained for each homogenization scheme. On this basis, an empirical upper bound estimation model was suggested to account for the influences of anisotropic damage growth, connectivity, frictional sliding, dilatancy, and normal stiffness recovery of closed microcracks, as well as tensile stress-induced microcrack opening on the permeability variation, with a small number of material parameters. The developed model was calibrated and validated by a series of existing laboratory triaxial compression tests with permeability measurements on crystalline rocks, and applied for characterizing the excavation-induced damage zone and permeability variation in the surrounding granitic rock of the TSX tunnel at the Atomic Energy of Canada Limited's (AECL) Underground Research Laboratory (URL) in Canada, with an acceptable agreement between the predicted and measured data.
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| 3. |
- Chen, Y., et al.
(författare)
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Numerical model for fully coupled THM processes with multiphase flow and code validation
- 2009
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Ingår i: Chinese Journal of Rock Mechanics and Engineering. - 1000-6915. ; 28:4, s. 649-665
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Tidskriftsartikel (refereegranskat)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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| 6. |
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| 7. |
- Jing, Lanru, et al.
(författare)
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Discrete Fracture Network (DFN) Method
- 2007
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Ingår i: Fundamentals Of Discrete Element Methods For Rock Engineering. - : Elsevier. - 9780444829375 ; , s. 365-398
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Bokkapitel (refereegranskat)
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