Thermo-mechanical coupling processes

Glacier-permafrost coupling creates a distinctive hydraulic regime, dominated by transient processes, which must be understood for long term safety assessments. In principle, the problem should be solved by a thermo-mechanically coupled model of the whole ice-water-rock system, driven by an external climate function. As an interim step, we use two separate models, one for... 

To understand and predict the effects of coupled processes in all these practical problems, models are being developed that are capable of simulating coupled thermo-hydro-mechanical (THM) processes. The term coupled processes implies that one process affects the initiation and progress of another. Thus, the rock mass behavior cannot be predicted with confidence by considering each process individually or in simple succession. Previously, binary TM and TH couplings have been studied in the context of, for example, rock... 

Ohnishi, Y., Shibata, H. and Kobayashi, A. 1987. Development of finite element code for the analysis of coupled thermo-hydro-mechanical behavior of a saturated-unsaturated medium. In Tsang, C.-F. editor. Coupled processes associated with nuclear waste repositories. Academic lYess, Orlando, pp.551-557. 

Model performance is demonstrated for a simplified three-dimensional test case that takes into consideration both the thermo-hydro-mechanical interaction and a stress dependent permeability. The functionality of the described control concept for the coupled processes is illustrated by some selected simulations of Benchmark Test IB (BMTIB) of DECOVALEX III. 

All these processes are the product of a system driven by the Earth s climate and characterised by strong thermo-hydro-mechanical coupling, in which both chemical processes and transient phenomena are important. 

This paper presents a numerical simulation of the swellin shrinking processes using the numerical model RF-TH/M - a fully coupled thermo-hydraulic model with mechanical coupling - which has been developed for the purpose of modelling non-isothermal multiphase flow in swelling porous media. In this paper details of the mathematical and numerical multiphase-multicomponental formulation for bentonite, as well as code implementation are described. As an example a test case is investigated. 

This model is implemented in the novel object-oriented simulator RockFlow-TH/M - a fully coupled thermo-hydraulic model with mechanical coupling, which can be used to simulate non-isothermal moisture transport processes and the corresponding swelling effects. 

Ohnishi, Y., Shibata, H. Kobayashi, A. 1985. Development of Finite Element Code for the Analysis of Coupled Thermo-Hydro-Mechanical Behaviors of a Saturated-Unsaturated Medium. Proc. Int. Symp. on Coupled Process Affecting the Preformance of a Nuclear Waste Repository. Berkeley pp.263-268. 

Abstract motif is a three-dimensional finite-element code developed to simulate groundwater flow, heat transfer and solute transport in deformable fractured porous media. The code has been subjected to an extensive verification and updating programme since the onset of its development. In this paper, additional verification and validation works with an emphasis on thermo-hydro-mechanical processes are presented. The verification results are based on cases designed to verify thermo-hydro-mechanical coupling terms, and isothermal and non-isothermal consolidations. A number of validation case studies have been conducted on the code. Example results are repotted in this paper. 

COUPLED THERMO HYDRO MECHANICAL-CHEMICAL PROCESSES IN GEO-SYSTEMS... 

Coupled Thermo-Hydro-Mechanical-Chemical Processes in Geo-Systems... 

I am pleased to be able to introduce this book on Coupled thermo-hydro-mechanical-chemical processes in geo-systems fundamentals, modelling, experiments and applications as the second publication in the Elsevier Geo-Engineering Book Series. The book contains the proceedings of the GeoProc2003 conference held at the Royal Institute of Technology in Stockholm, Sweden, in October 2003. 

Stereo-complex films were reported by Masutani et al7 % combining bifunctional PLLA and PDLA pre-polymers, multi-stereo-block copolymers having different block lengths and sequences are obtained. The resultant copolymers are readily fabricated into transparent films by hot-pressing. The films present excellent thermal stability and thermo-mechanical properties because of the easy formation of stereo-complex crystals. This synthetic method based on tbe dual terminal couplings allows obtaining stereo-block copolymers of PLLA and PDLA showing excellent thermo-mechanical properties and melt processability. 

Abstract A fully coupled model of hygro-thermo-chemo-mechanical phenomena in concrete is presented. A mechanistic approach has been used to obtain the governing equations, by means of the hybrid mixture theory. The final equations are written in terms of the chosen primary and internal variables. The model takes into account coupling between hygral, thermal, chemical phenomena (hydration or dehydration), and material deformations, as well as changes of concrete properties, caused by these processes, e.g. porosity, permeability, stress-strain relation, etc. 

The coupling effects of various poromechanical processes on the response of a porous medium have been successfully addressed by Biot s theory of poroelasticity and its extensions [3,4,5,8,2], The chemical effects have also been addressed by considering interaction between the porous matrix and a pore fluid comprising of a solute and solvent [10, 7, 6], Comprehensive anisotropic poromechanics formulations and corresponding solutions for the inclined borehole problem have been presented [4—2], However, the coupled chemo-thermo-hydro-mechanical response of an anisotropic porous medium has not been addressed to date. 

Stephansson, O., L. Jing and C.-F. Tsang. 1996. Coupled Thermo-Hydro-Mechanical Processes of Fractured Media—Mathematical... 

Models and methods for coupled thermo-hydro-mechanical processes of fractured rocks, in saturated conditions using crack-tensor approach (Liu et al., 2002), the equivalent continuum approach and FEM solution technique with consideration for two-phase flow of water/vapour due to phase change by evaporation for fully or partially saturated cases (Li et al., 2000). 

Fujita T., Kobayashi A. and Borgesson L. 1996. Experimental investigation and mathematical simulation on coupled T-H-M processes of the engineered buffer materials, the TC3 problem. In Stephansson O, Jing L, Tsang C-F editors. Coupled thermo-hydro-mechanical processes of fractured media. Developments in Geotechnical Engineering, No.79, Amsterdam Elsevier, pp.369-392. 

Tijani, S.M. 1996. Short description of VIPLEF code. Coupled thermo-hydro-mechanical processes of fractured media. Developments in Geotechnical Engineering, 79 507 - 511. 

NUMERICAL SIMULATION OF VARIABLY COUPLED THERMO-HYDRO-MECHANICAL PROCESSES IN FRACTURED POROUS MEDIA... 

Nguyen TS, Chijimatsu M, De Jonge J, Jing L, Kohlmeier M, Millard A, Rejeb A, Rutqvist J, Souley M and Sugita Y. 2003. Implications of coupled Thermo-Hydro-Mechanical processes on the safety of a hypothetical nuclear fuel waste repository. GeoProc, Stockholm, Sweden... 

Ohnishi, Y. and Kobayashi, A. 1996. THAMES. In Stephansson, O., Jing, L., and Tsang, C.-F. editors. Coupled Thermo-hydro-mechanical Processes of Fractured Media. Developments in Geotechnical Engineering, Elsevier, 79 pp. 545-549. 

IMPLICATIONS OF COUPLED THERMO-HYDRO-MECHANICAL PROCESSES ON THE SAFETY OF A HYPOTHETICAL NUCLEAR FUEL WASTE REPOSITORY... 

A RESEARCH PROGRAM FOR NUMERICAL EXPERIMENTS ON THE COUPLED THERMO-HYDRO-MECHANICAL AND CHEMICAL PROCESSES IN THE NEAR-FIELD OF A HIGH-LEVEL RADIOACTIVE WASTE REPOSITORY... 

Abstract In the near-field of a high-level radioactive waste (HLW) repository, the coupled thermo -hydro -mechanical and chemical (T-H-M-C) processes will occur. Observation periods by laboratory and in-situ experiments are very short and information by natural analogue studies is very limited, so numerical experiments are the only available approach to predict the near-field long-term evolution. We have initiated a research on the coupled T-H-M-C processes and are trying to carry out numerical experiments on the coupled T-H-M-C processes in order to predict the near-field long-term evolution. This paper presents our current status and future activities on the research for numerical experiments on the coupled T-H-M-C processes. 

In the near-field of a HLW repository, the coupled thermo -hydro -mechanical and chemical (T-H-M-C) processes will occur, involving the interactive processes among radioactive decay heat from the vitrified waste, infiltration of groundwater into bentonite, swelling pressure of bentonite due... 

Our activities on development of the coupled T-H-M-C code and further demonstration analysis are presented by Neyama et al. in GeoProc 2003 conference, entitled Prototype Code Development for Numerical Experiments on the Coupled Thermo-Hydro-Mechanical and Chemical Processes in the Near-field of a High-level Radioactive Waste Repository . The prototype code is based on the coupled T-H-M code, mass transport code and geochemical code which have been well verified and validated through benchmark tests and various experiments, and... 

Japan Nuclear Cycle Development Institute (JNC) has already developed the coupled thermo -hydro and mechanical (T-H-M) model and has initiated a research on the coupled T-H-M-C processes to predict the chemical evolution of buffer material and porewater chemistry, and the chemical effects on other (thermal, hydraulic and mechanical) processes. In this research, numerical experiment system for the coupled T-H-M-C processes is developed in order to predict the longterm evolution of the near-field (engineered barriers and surrounding host rock) for various repository designs and geological environments. 

Numerical Approximation of Partial Differential Equations. Springer-Verlag, Berlin. Stephansson, 0., Jing, L., Tsang, C.F. (eds.) 1996. Coupled Thermo-Hydro-Mechanical Processes of Fractured Media. Elsevier, Amsterdam. Stephansson, O. (ed.) 2001. DECOVALEX II. Special issue of Int. J. Rock. Mechanics and Mining Sciences 38(1). 

Rutqvist, J., Follin, S., Khair, K., Nguyen, S. and Wilcock, P. 1996. Experimental investigation and mathematical simulation of a borehole injection test in deformable rocks. In Coupled Thermo-Hydro-Mechanical Processes of Fractured Media,... 

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