Hydro-mechanics

D. S. Mfller, IntemalFlow, Cranfield British Hydro Mechanical Research Association, 1971. 

Navi, P. and Girardet, E. (2000). Effects of thermo-hydro-mechanical treatment on the structure and properties of wood. Holzforschung, 54(3), 287-293. 

Georgian gas mains are complex hydro-mechanical systems and their operation reliability depends on many factors. Complexity of gas mains caused by profile and long distances of transportation requires the creation of multistage systems with consecutive connections of compressor stations in pipeline segments, several take off points for various consumers and other armature for control and regulation of gas flow. 

M. Sasic, P. Marjanovic. One more general approach for investigation of hydro-mechanics of two-component systems, J. Powder Bulk Solids Tech. 5 (1) (1981) 13-19. 

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. 

In this paper, the focus is on the development of a poromechanics model which addresses the chemical effects within the framework of the anisotropic porothermoelastic model [2], The resulting model, termed as porochemo-thermoelastic, accounts for fully coupled chemo-thermo-hydro-mechanical response of a chemically active formation saturated with a pore fluid comprising of two species under non-isothermal conditions. The numerical example presented demonstrates the thermo-chemical effect on the stress and pore pres-... 

Figure 10.11 A hydro-mechanical analogy for load changes during squeezing (after Lambe and Whitman, 1979).

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... 

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). 

Chen B, Li N and Zhuo R. 2001. FEM analysis on fully coupled thermo-hydro-mechanical behaviour of porous media. Chinese J. of Rock Mech. Engng., 20(4), pp. 467-472. 

Wu Wenhua and Li Xikui, 2002, Constitutive model and numerical simulation of thermo-hydro-mechanical behavior in unsaturated soils, Chinese J. Geotech. Eng., Vol.24, No.4, pp.411-416... 

In addition to the clay barrier and the heaters, 632 sensors of diverse types were installed. The sensors monitor the different thermo-hydro-mechanical processes that occur in both the clay barrier and the surrounding rock throughout the entire life of the test. A heating stage of more than three years was planned, followed by dismantling of the test. The present paper reports on the measurements recorded during the first 1000 days of operation. 

Based on the available geological, hydraulic and mechanical characterizations of the Site as well as on results of hydraulic tests performed on boreholes, a hydro-mechanical model for the zone around the FEBEX tunnel was to be prepared. Using this model, changes in water pressure induced by the boring of the FEBEX tunnel in the near vicinity, as well as the total water flow rate to the excavated tunnel was required. 

Based on the characterization of the bentonite and on the details of the process of test installation, a thermo-hydro-mechanical model for the bentonite barrier and the heaters was to be prepared. Using this model, the thermo-hydro-mechanical response of the bentonite barrier as a result of the heat released by the heaters and the hydration from the host rock was required. Local field variables such as temperature, relative humidity, pore water pressure, stresses and displacements, as well as global... 

Part C Thermo-hydro-mechanical analysis of the rock. 

This behavior is related to the interaction between rock deformation and water pressure and provides an interesting record of hydro-mechanical interaction in the saturated granitic rock mass. Figure 13 is a Plan view of the Febex tunnel and the Borehole FEBEX 95.002 where observations were made in the intervals P3 and P4. 

Pore water pressure changes in the vicinity of the tunnel excavation are a direct consequence of changes in the volumetric strain of the rock. Later, pore water pressure dissipations are a consequence of the transition flow towards a new equilibrium, which now has a modified boundary condition (the tunnel surface) in the vicinity. Therefore, fully coupled hydro-mechanical analyses are required to try to capture actual measurement. In fact, one-way... 

PART B THERMO-HYDRO-MECHANICAL ANALYSIS OF THE BENTONITE BEHAVIOUR. 

PART C THERMO-HYDRO-MECHAN-ICAL ANALYSIS OF THE ROCK... 

Romero, E., Villar, M.V., and Lloret, A., Thermo-hydro-mechanical behavior of two heavily overconsolidated clays. 6 Int. Workshop on Key Issues in Waste Isolation Research. Barcelona, 2001. 

Villar, M.V., Thermo-hydro-mechanical character-rization of a bentonite from Cabo de Gata. A study applied to the use of bentonite sealing material in high level radioactive waste repositories. PhD Dissertation and Enresa Technical Publication 01/2002. Madrid. 

Villar, M.V., Martin, P.L., Lloret, A., and Romero, E., Second report on thermo-hydro-mechanical laboratory tests. CIMNE-CIEMAT Report n° 70-IMA-L-0-97, 2002. 

Abstract The Canadian Nuclear Safety Commission (CNSC) used the finite element code FRACON to perform blind predictions of the FEBEX heater experiment. The FRACON code numerically solves the extended equations of Biot s poro-elasticity. The rock was assumed to be linearly elastic, however, the poro-elastic coefficients of variably saturated bentonite were expressed as functions of net stress and void ratio using the state surface equation obtained from suction-controlled oedometer tests. In this paper, we will summarize our approach and predictive results for the Thermo-Hydro-Mechanical response of the bentonite. It is shown that the model correctly predicts drying of the bentonite near the heaters and re-saturation near the rock interface. The evolution of temperature and the heater thermal output were reasonably well predicted by the model. The trends in the total stresses developed in the bentonite were also correctly predicted, however the absolute values were underestimated probably due to the neglect of pore pressure build-up in the rock mass. 

The research teams participating in the DECOVALEX III project were asked to predict the Thermo-Hydro-Mechanical (THM) response of both the bentonite and the rock mass after the commencement of the heating (from day 0). This paper summarizes the approach and results from the CNSC team for the bentonite response. 

Nguyen, T.S., Borgesson, L., Chijimatsu, M., Rutqvist, J., Fujita, T., Hemelind, J., Kobayashi, A., Onishi, Y., Tanaka, M. and Jing, L. IQOi.Hydro-mechanical response of a fractured granitic rock mass to excavation of a test pit-the Karnaishi Mine experiment in Japan. Int. J. Rock Mech. Min. Sci., 38(1) pp 79-94. 

UPC, 2000, Task definition DECOVALEX III, Task 1 Modelling of FEBEX in-situ test. Part B Thermo-hydro-mechanical analysis of the bentonite behaviour. Polytechnical University of Catalonia, Barcelona, Spain. 

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. 

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. 

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... 

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