Distinct element models for the coupled T-H-M processes: Theory and implementation

• Published in: Coupled Thermo-Hydro-Mechanical Processes of Fractured Media - Mathematical and Experimental Studies Vol. 79; pp. 181 - 211
• Main Authors: Ahola, Mikko P., Thoraval, Alain, Chowdhury, Asadul H.
• Format: Book Chapter
• Language: English
• Published: Elsevier B.V 1996; Elsevier
• Subjects: Earth Sciences; Geotechnical Engineering
• ISBN: 9780444825452; 0444825452
• ISSN: 0165-1250
• DOI: 10.1016/S0165-1250(96)80026-5

Numerical assessment of the design and long-term performance of deep underground disposal facilities for high-level radioactive waste in jointed rock has led to the increased use of discontinuum modeling approaches to evaluate the coupled T-H-M effects within the immediate vicinity of the waste emplacement drifts. This is particularly true with regard to accurate determinations of the long-term mechanical deformations of the fractured rock mass around the emplacement drifts/boreholes due to thermal and other loads, as well as accurate determination of fluid fluxes into the drifts which could take place along selected preferential fracture. pathways. This chapter presents the basic theoretical background and numerical formulation of the distinct element method for each of the individual as well as two-component (e.g., T-M, M-H, and T-H) processes, and approaches for T-H-M modeling of fractured media for either transient or steady state conditions. Particular emphasis is placed on extension of the distinct element method to simulate the thermal-hydrologic coupling in fluid filled fractures. Results are presented to show that thermal convection in flowing fractures can have a very important effect on the fluid and adjacent rock temperatures depending on the fracture hydraulic aperture, fluid velocity, and fluid viscosity.