緩衝材料是一種對源質隔絕以及保護之介質。於本研究中，緩衝材料係指膨潤土。膨潤土基本上是含有不少於85％黏土礦物 (蒙脫石) 的塑性黏土。膨潤土的商業重要性更多取決於其物理化學性質。優異的可塑性和潤滑性、具較高的剪切和抗壓強度，以及低滲透與低壓縮等特性，使其具備一定工程與經濟之價值。膨潤土經常運用在鑄造、鑽井泥漿，鐵礦石造粒和作為土木工程中的防水和密封劑。近年，在瑞典等等北歐國家將其作為填充在核廢料周圍的最佳緩衝材料。
為了探討膨潤土在熱¬-水-力交互作用下的工程性質，本研究使用TOUGH2計算熱場和流場，而FLAC3D則是解析力學，並利用MATLAB作為兩套軟體間之資料傳輸以及差分。此外，本研究使用Visual Studio中之 C++語言撰寫FLAC3D內部所提供的使用者自定義模型 (User-Defined-Model, UDM)，並且編譯成動態鏈接檔（Dynamic-link library, DLL），將FLAC3D內建劍橋模型 (Cam-Clay model, CCM)改寫為適用於計算吸力應變之巴塞隆納基本模型 (Barcelona Basic Model, BBM)，以利於兩套軟體運作之熱-水-力耦合分析。另外，本研究係透過吸力變化量之差值，與其造成之吸力與彈性體積模數之比值，進一步描述吸力變化所構成之體積應變量。在數值模擬過程中，泊松比將因材料進入塑性階段產生明顯的變化。然而，本研究調整吸力變化剛性係數 (κ_s) 之予以滿足材料進入塑性階段後泊松比修正之條件。
本研究以相關文獻資料驗證本研究數值模式，其結果顯示與文獻之料頗為吻合，故確立本模式之適用性。在案例研究中，以一熱-水-力耦合縮尺實驗 (mock up test) 建構多材料組合之幾何模型，予以探討非飽和緩衝材料受熱荷載影響1080天之熱-水-力耦合行為。其溫度、吸力、膨脹應力等結果顯示，模型邊界溫度(室溫變化)具有較大之影響。

The buffer material is a kind of medium that is for isolation and mechanical protection for source material. In this study, the buffer material was bentonite. Bentonite is basically a plastic clay containing not less than 85% clay minerals (montmorillonite). The commercial importance of bentonite depends more on its physicochemical properties. Excellent plasticity and lubricity, high shear and compressive strength, as well as low permeability and low compressibility, make it a certain engineering and economic value. Bentonite is often used in foundry, drilling mud, iron ore pelleting and as a waterproofing and sealing agent in civil engineering. In recent years, bentonite is considered as the best buffer material for filling around nuclear waste in Nordic countries such as Sweden.
In order to investigate the engineering properties of bentonite under the interaction of thermo-hydro-mechanical interaction, this study employs TOUGH2 to calculate thermal and hydraulic simulation, and FLAC3D is to resolve the mechanics. We collect MATLAB programs for data transfer and interpolation. In addition, this study expands the capacity of the original modified Cam-Clay model (CCM) by collecting a User-Defined Model (UDM) into a Dynamic-link library (DLL) to numerically achieve thermo-hydro-mechanical (THM) coupling in FLAC3D. The Cam-Clay model is expanded into Barcelona Basic Model (BBM) for calculating suction strains to achieve the thermo-hydro-mechanical coupling analysis in the two software. In the numerical simulation process, Poisson's ratio will change significantly as the material enters the plastic stage. However, the study adjusted the compressibility parameter for suction-induced elastic strain (κ_s). to meet the conditions for the Poisson's ratio correction after the material entered the plastic stage.
We used relevant literature data to verify the numerical model of this study. The results show that the data is in good agreement with the literature. Thus, the applicability of this model is established. In the case study, a complex geometric model with multi-material for the non-saturated buffer material under thermal loading for 1080 days was investigated. The results of temperature, suction, and swelling stress show that the model boundary temperature (change in room temperature) has a significant impact on the mock up test.

Alonso, E. E., A. Gens & A. Josa (1990). A constitutive model for partially saturated soils. Geotechnique 40(3): 405–430.
Dueck, A. & U. Nilsson (2008). Thermo-Hydro-Mechanical properties of MX-80 (SKB Technical Report TR-10-55). Swedish Nuclear Fuel and Waste Management Press.
Bodvarsson, G. S., K. Pruess, C. Haukwa, S. B. Ojiambo (1990). Evaluation of reservoir model predictions for the Olkaria geothermal field. Geothermics, 19(5):399-414.
Börgesson L, M. Åkesson, M. Birgersson, H. Hökmark & J. Hernelind (2016). EBS TF – THM modelling. BM 1 – Small scale laboratory tests (SKB Technical Report TR-13-06). Sweden: Swedish Nuclear Fuel and Waste Management Company Press.
Börgesson, L., L. E. Johannesson, T. Sandén, & J. Hernelind (1995). Modelling of the physical behaviour of water saturated clay barriers. Laboratory tests, material models and finite element application. (SKB Technical Report TR-95-20). Sweden: Swedish Nuclear Fuel and Waste Management Company Press.
Bossart, P., F. Bernier, J. Birkholzer, C. Bruggeman, P. Connolly, S. Dewonck, M. Fukaya, M. Herfort, M. Jensen, J. M. Matray, J. C. Mayor, A. Moeri, T. Oyama, K. Schuster, N. Shigeta, T. Vietor & K. Wieczorek (2017). Mont Terri rock laboratory, 20 years of research: introduction, site characteristics and overview of experiments. Swiss Journal of Geosciences.
CIMNE (2002). Code_Bright User's Guide, Part V1d Thermo-Elasto-Plastic Constitutiva Model. Universidad Polite´ cnica de Catalun˜a, Barcelona, Spain.
Davies, J. P. & D. K. Davies (1999). Stress-dependent permeability: characterization and modeling. Society of Petroleum Engineers.
Doughty, C. & K. Pruess (1990). A Similarity Solution for Two-Phase Fluid and Heat Flow Near High-Level Nuclear Waste Packages Emplaced in Porous Media. International Journal of Heat and Mass Transfer, 33(6): 1205-1222.
Doughty, C. & K. Pruess (1992). A similar solution for two-phase water, air, and heat flow near a linear heat source in a porous medium. Journal of Geophysical Research: Solid Earth, 97(B2): 1821-1838.
Euler, L. Foundations of Differential Calculus. New York: Springer-Verlag, 2000. Translation of first nine chapters of Institutiones Calculi Differentialis, published in 1755.
Falta R. W. & K. Pruess (1995). STMVOC User's Guide. California: Lawernce Berkeley National Laboratory.
Falta, R. W., K. Pruess. & L. Javandel (1992). Numerical modeling of steam injection for the removal of nonaqueous phase liquids from the subsurface. Water Resources Research, 28(2): 451-564.
Gens, A., P. Jouanna & B. Schrefler (1995). Constitutive laws. In: Modern Issues in Non-saturated Soils. New York: Springer: 129-158.
Gens, A., M. Sánchez & D. Sheng (2006). On constitutive modelling of unsaturated soils. Acta Geotechnica, 1(3): 137-147.
Gingold, R. A. & J. J. Monaghan (1977). Smoothed particle hydrodynamics: theory and application to non-spherical stars. Monthly Notices of the Royal Astronomical Society, 181(1): 375-389.
Gunnarsson, D., L. Morén, P. Sellin & P. Keto (2006). Deep repository – engineered barrier systems. Swidish: Svensk Kärnbränslehantering AB.
Hueckel T. & M. Borsetto (1990). Thermoplasticity of saturated soils and shales: Constitutive equations. Journal of Geotechnical Engineering, 116(12): 1765-1777.
Hung, H. C. & T .W. Wang (2011). Determinants and Mapping of Collective Perceptions. Risk Analysis, 31(4), p. 668–683.
Hunt, J. R. & N. Sitar (1988). Nonaqueous phase liquid transport and cleanup. Water Resources Research, 24(8): 1259-1269.
Itasca (2009). Fast Lagrangian Analysis of Continua in 3 Dimensions User's Guild. USA: Itasca Consulting Group.
Iwano, M. (1995). Hydromechanical characteristics of a single rock joint. USA: Massachusetts Institute of Technology
Rutqvist, J., Y. S. Wu, C. F. Tsang, G. Bodvarsson (2002). A modeling approach for analysis of coupled multiphase fluid flow, heat transfer, and deformation in fractured porous rock. International Journal of Rock Mechanics & Mining Sciences, 39(4): 429–442.
Rutqvist, J., Y. Ijiri & H. Yamamoto (2011). Implementation of the Barcelona Basic Model into TOUGH–FLAC for simulations of the geomechanical behavior of unsaturated soils. Computers & Geosciences, 37(6): 751-762.
Joaquin, M. & P. Cundall (1982). Mixed discretization procedure for accurate modelling of plastic collapse. International Journal for Numerical an Analytical Methods in Geomechanics, 6(1): 129-139.
Ju, S. J. (2010). Performance assessment system for deep geologic repository for radioactive waste disposal. USA: Patent No. 8,521,432.
Komine, H. & N. Ogata (1994). Experimental study on swelling characteristics of compacted bentonite. Canadian Geotechnical Journal, 31(4) 478-490.
Kristensson, O. & M. Åkesson (2008a). Mechanical modeling of MX-80—quick tools for BBM parameter analysis. Physics and Chemistry of the Earth, 33(1): S508–S515.
Kristensson, O. & M. Åkesson (2008b). Mechanical modeling of MX-80- Development of constitutive laws. Physics and Chemistry of the Earth, 33(1) S504-S507.
Lam, S. T., A. Hunsbedt & P. Kruger (1988). Analysis of the stanford geothermal reservoir model experiments using the LBL reservoir. Stanford. 17(4): 595-605
Lauwerier, H. A. (1955). The Transport of Heat in an Oil Layer Caused by the Injection of Hot Fluid. Applied Scientific Research, Section A: 5(2): 145-150.
Leverett, M. (1941). Capillary behavior in porous solids. Society of Petroleum Engineers. IDO: 10.2118/941152-G
Li, J. & Y. T. Chen (2008). Computational Partial Differential Equations Using MATLAB. CRC Press, Inc.
Lim, B. F. & G. A. Siemens (2016). Unifying framework for modeling swelling soil behaviour. Canadian Geotechnical Journal, 53(9): 1495-1509.
Mendoza, C. E., J. E. Colmenares & V. E. Merchán (2005). Stiffness of unsaturated compacted clayey soils at very small strains, Proc. Int. Symp. on Advanced Experimental Unsaturated Soil Mechanics, Trento, Italy, 2005: 199-204.
Oh, W. T. & S. K. Vanapalli (2011). Relationship between Poisson’s ratio and soil suction for unsaturated soils. Conference: 5th Asia-Pacific Conference on Unsaturated Soils, At Pattaya, Thailand, 1(1).
Olivella, S., A. Gens, J. Carrera, E. E. Alonso (1996). Numerical formulation for a simulator CODE_BRIGHT for the coupled analysis of saline media. Engineering Computations, 13(7): 87-112.
Özişik, M., M. Colaço & R. Cotta (2017). Finite Difference Methods in Heat Transfer. CRC Press, Inc.
Persoft, P. & K. Pruess (1995). Two-phase flow visualization and relative permeability measurement in natural rough-walled rock fractures. Water Resources Research, 31(5): 1175-1186.
Pettersson, S. & B. Lönnerberg (2008). Final repository for spent nuclear fuel in granite – the kbs-3v concept in sweden and finland. International Conference: Underground Disposal Unit Design & Emplacement Processes for a Deep Geological Repository, Prague: 16-18.
Pruess, K. & Y. S. Wu (1988). Well Treatment, and the Preparation of Input Data for an Isothermal Gas-Water-Foam Version of MULKOM, California: Lawrence Berkeley National Laboratory.
Pruess, K. (1983). Development of the general purpose simulator MULKOM, Report LBL-15500. Lawrence Berkeley National Laboratory..
Pruess, K. (1991). TOUGH2- A General Purpose Numerical Simulator for Multiphase Fluid and Heat Flow. Lawrence Berkeley National Laboratory.
Pruess, K. & G. S. Bodvarsson (1984). Thermal effects of Reinjection in Geothermal Reservoird with Major versical fractires. 36(9): 1567-1578.
Pruess, K., C. Calore, R. Celati & Y .S. Wu (1991). An analytical solution for heat transfer at a boiling front moving through a porous medium. International Journal of Heat and Mass Transfer, 30(12): 2595-2602.
Pruess, K. & R. McKibbin (1989). Some effects of non-condensible gas in geothermal reservoirs with steam-water counterflow. Geothermics, 18(3): 367-375.
Pruess, K. & N. T. Narasimhan (1985). A Practical Method for Modeling Fluid and Heat Flow in Fractured Porous Media. Society of Petroleum Engineers Journal, 25(1): 14-26.
Runge, C. (1908). Analytische Geometrie der Ebene. Ann Arbor, Michigan: University of Michigan Library.
Narasimhan T. N. & P. A. Witherspoon (1976). An Integrated Finite Difference Method for Analyzing Fluid Flow in Porous Media. Water Resources Research, 12(1): 57-64.
Teodori, S. P. & L. Gaus (2012). Report of the construction of the HE-E experiment. PEBS Deliverable D2.2-3.
Walsh, J. B.(1981). Effect of pore pressure and confining pressure on. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 18(5): 429-435.
Warren, J. E. & P. J. Root (1963). The Behavior of Naturally Fractured Reservoirs. Society of Petroleum Engineers Journal, 3(3): 245-255.
Wieczorek , K., L. Gaus, K. Schuster & T. Sakaki (2017). In-situ experiments on bentonite-based buffer and sealing materials at the Mont Terri rock laboratory. Swiss Journal of Geosciences, 110(1): 3-22.
Wu, Y. S., K. Pruess & P. A. Witherspoon (1991). Displacement of a Newtonian fluid by a non-Newtonian fluid in a porous medium. Transport in Porous Media, 6(2): 115-142.
Zhao, J., L. Chen, F. Collin, Y. Liu, J. Wang (2016). Numerical modeling of coupled thermal-hydro-mechanical behavior of GMZ bentonite in the China-Mock-up test. Engineering Geology. Volume 214(1): 116-126.
Zienkiewicz, O. C. & Y. K. Cheung (1967). The Finite Element Method in Structural and Continuum Mechanics.