2010-02期电子版文档 [复制链接]

A. Gens^1*, L. do N. Guimarães², S. Olivella¹, M. Sánchez^3
1Department of Geotechnical Engineering and Geosciences, Technical University of Catalonia, Barcelona, Spain
²Universidade Federal de Pernambuco, Recife, Brazil
³Texas A & M University, College Station, USA
Received 21 May 2009; received in revised form 14 May 2010; accepted 6 June 2010

Abstract: A fully coupled thermo-hydro-mechano-chemical (THMC) formulation is described in this paper. Special attention is paid to phenomena likely to be encountered in clay barriers used as engineered barriers in the disposal of nuclear radioactive waste. The types of processes considered in the chemical formulation include hydrolysis, complex formation, oxidation/ reduction reactions, acid/base reactions, precipitation/dissolution of minerals and cation exchange. Both kinetics- and equilibrium-controlled reactions are incorporated. The formulation is implemented in a numerical code. An application is presented concerning the performance of a large-scale in-situ heating test simulating high-level radioactive waste repository conditions.

Key words: coupling analysis; thermo-hydro-mechano-chemical (THMC) analysis; radioactive waste; engineered barriers; bentonite; cation exchange

2010-02-01.pdf (133 K) 下载次数:67

Design and development of large-scale in-situ PRACLAY heater test and horizontal high-level radioactive waste disposal gallery seal test in Belgian HADES

X. L. Li1, W. Bastiaens1, P. Van Marcke1, J. Verstricht1, G. J. Chen1, E. Weetjens2, X. Sillen3
1European Underground Research Infrastructure for Disposal of Nuclear Waste in Clay Environment, EURIDICE, Mol, 2400, Belgium
2 Belgian Nuclear Research Center (SCK•CEN), Mol, 2400, Belgium
3 Belgian Agency for Radioactive Waste and Enriched Fissile Materials (ONDRAF/NIRAS), Brussel, 1210, Belgium
Received 15 May 2009; received in revised form 14 November 2009; accepted 6 January 2010


Abstract: In Belgium, the Boom clay was selected as a potential host formation for the disposal of high-level radioactive waste (HLW). To demonstrate the suitability of Boom clay for bearing thermal load induced by the HLW, a large-scale in-situ heater test, called PRACLAY heater test, will be conducted in the underground research laboratory (URL) in Mol. Owing to the limitations of the test (a short period of time compared with that considered in a real repository, different boundary conditions, etc.), the test is designed to simulate, in a conservative way, the most critical state and phenomena that could occur in the host rock. The PRACLAY gallery was excavated at the end of 2007; the heating phase will begin in 2010 and will last for at least 10 years. The PRACLAY gallery itself leaves an opportunity to study the possibilities of sealing a disposal drift in Boom clay and testing the feasibility of hydraulic cut-off of any preferential pathway to the main access gallery through the excavation damage zone (EDZ) and the lining with a seal in a horizontal drift (horizontal seal). Indeed, this is a generic problem for all deep geological disposal facilities for HLW. An annular seal made of compacted swelling bentonite will be installed in the front of the heated part of the PRACLAY gallery for these purposes.
This paper provides detailed considerations on the thermo-hydro-mechanical (THM) boundary conditions for the design of the PRACLAY heater test and the seal test with the support of numerical calculations. It is believed that these important items considered in the PRACLAY heater test design also constitute key issues for the repository design. The outcome of the PRACLAY heater test will be an important milestone for the Belgian repository design.
Key words: high-level radioactive waste (HLW); Boom clay; PRACLAY heater test; hydraulic cut-off; thermo-hydro- mechanical (THM) boundary conditions; scoping calculation

2010-02-02.pdf (1346 K) 下载次数:40

Clays in radioactive waste disposal

P. Delage, Y. J. Cui, A. M. Tang
UR Navier/CERMES, Ecole des Ponts ParisTech, Paris, 77455, France
Received 28 May 2009; received in revised form 20 October 2009; accepted 28 November 2009


Abstract: Clays and argillites are considered in some countries as possible host rocks for nuclear waste disposal at great depth. The use of compacted swelling clays as engineered barriers is also considered within the framework of the multi-barrier concept. In relation to these concepts, various research programs have been conducted to assess the thermo-hydro-mechanical properties of radioactive waste disposal at great depth. After introducing the concepts of waste isolation developed in Belgium, France and Switzerland, the paper describes the retention and transfer properties of engineered barriers made up of compacted swelling clays in relation to microstructure features. Some features of the thermo-mechanical behaviors of three possible geological barriers, namely Boom clay (Belgium), Callovo-Oxfordian clay (France) and Opalinus clay (Switzerland), are then described, including the retention and transfer properties, volume change behavior, shear strength and thermal aspects.
Key words: high-level radioactive waste (HLW); engineered barrier; temperature; permeability; radioactive waste disposal; swelling clay

2010-02-03.pdf (3802 K) 下载次数:48

Heating pulse tests under constant volume on Boom clay

A. Lima1, E. Romero1*, A. Gens1, J. Muñoz2, X. L. Li3
1 Department of Geotechnical Engineering and Geosciences, Universitat Politècnica de Catalunya, Barcelona, Spain
2 Department of Civil Engineering, Universidad Nacional de San Juan, San Juan, Argentina
3 EIG EURIDICE/SCK•CEN, Mol, Belgium
Received 15 May 2009; received in revised form 14 November 2009; accepted 6 January 2010


Abstract: Boom clay formation is a potential natural host rock for geological disposal of high-level nuclear waste in Belgium. Heating pulse tests with controlled power supply (maximum temperature was limited to 85 °C) and controlled hydraulic boundary conditions were performed under nearly constant volume conditions to study the impact of thermal loading on the clay formation. Selected test results of intact borehole samples retrieved in horizontal direction are presented and discussed. The study focuses on the time evolution of temperature and pore water pressure changes along heating and cooling paths, i.e. pore pressure build-up during quasi-undrained heating and later dissipation at constant temperature.
Key words: natural Boom clay; heating pulse test; pore pressure build-up; pore pressure dissipation

2010-02-04.pdf (350 K) 下载次数:48

Suction variations and soil fabric of swelling compacted soils

H. Nowamooz1, 2, F. Masrouri1
1 Laboratoire Environnement, Géomécanique & Ouvrages, Nancy Université, Vandoeuvre-lès-Nancy, France
2 Laboratoire de Génie de la Conception, INSA de Strasbourg, Strasbourg, France
Recieved 21 May 2009; recieved in revised form 8 May 2010; accepted 12 May 2010


Abstract：This study addresses firstly the soil fabric variations of loose and dense compacted soil samples during a single wetting/drying cycle at suctions between 0 and 287.9 MPa using mainly the mercury intrusion porosimetry (MIP) tests. Two suction techniques were employed to apply this wide suction range: the osmotic technique for suctions less than 8.5 MPa, and the vapor equilibrium or salt solution technique for suctions higher than 8.5 MPa. Secondly, the soil water retention curves (SWRCs) were predicted by the MIP test results for both loose and dense soil samples. A reasonable correspondence between MIP results and SWRCs was found on the wetting path at lower suctions close to saturation and on drying path at higher suctions.
Key words: expansive soil; experimentation; modelling; drying/wetting cycle

2010-02-05.pdf (261 K) 下载次数:55

A 13-parameter model for unsaturated soil based on bounding surface plasticity

H. Wong, M. Morvan, D. Branque
Département Génie Civil et Bâtiment, Université de Lyon, Ecole Nationale des Travaux Publics de L'Etat, Lyon, 69518, France
Received 21 May 2009; received in revised form 14 November 2009; accepted 6 January 2010


Abstract: A few constitutive models for unsaturated soils have already been proposed, however, many classic models such as the Barcelona basic model can simulate neither complex volumetric soil behaviour (without forgetting its supreme merit of being the first consistently and rigorously formulated model) nor post-peak softening, and most advanced models generally comprise a large number of parameters making them more difficult to be applied to practical situations. In this paper, we present a new model for unsaturated soils based on an existing model developed originally for saturated soils. It comprises a minimum number of constitutive parameters. The extension to unsaturated state is achieved by following a general methodology previously developed in our laboratory. The capacities of this simple model are tested. With only 13 parameters, it can reproduce the basic behaviour of unsaturated soils such as rebound or collapse upon wetting, depending on the stress levels. It can also reproduce post-peak softening and transition from contractant to dilatant volumetric behaviour during undrained shear. Overall, the first tentative of validation gives a good correlation between simulations and experimental data, and shows encouraging signs for future developments.
Key words: suction; effective stress; equivalent pore pressure; hardening; experimental validation

2010-02-06.pdf (1187 K) 下载次数:50

On the thermo-mechanical properties of unsaturated soils

Yingfa Lu1, Xinxing Wu1, Yujun Cui1, 2
1 Key Laboratory of Geological Hazards on Three Gorges Reservoir Area of Ministry of Education, China Three Gorges University, Yichang, 443002, China
2 UR NAVIER/CERMES, Ecole des Ponts ParisTech, Paris, 77455, France
Received 15 May 2009; received in revised form 30 May 2010; accepted 6 June 2010


Abstract: The establishment of energy balance equation is necessary to study the thermo-mechanical properties of unsaturated soils. To solve this equation, the determination of two fundamental parameters as volumetric specific parameter and thermal conductivity coefficient is essential. In this paper, the effective thermal conductivity coefficient of dry soil grain is analyzed for soils with different compositions, and the thermo-mechanical properties of porous media with water and gas are studied by considering the soil water retention curve (SWRC). Different methods, i.e. volumetric average method, self-consistent method, Hashin-Strikman method, are employed to calculate thermal conductivity coefficients, and a new method is proposed to determine the thermo-mechanical parameters. Comparison of the results obtained by different methods shows that the proposed method is in a good agreement with the experimental results and is suitable for describing the main properties of the thermo- mechanical behaviors of soils. The relationship between the SWRC and the seepage curve is further studied by the natural proportional rule. The characteristics of the SWRC, its differential coefficient and the seepage curve, are investigated by considering the physico-mechanical mechanism; the limit scopes of the indices of the SWRC and the seepage curve are also given.
Key words: unsaturated soil; soil water retention curve (SWRC); seepage curve; thermal conductivity coefficient; comparative analysis

2010-02-07.pdf (110 K) 下载次数:50

Unsaturated creep tests and empirical models for sliding zone soils of Qianjiangping landslide in the Three Gorges

Xiaoling Lai, Shimei Wang, Hongbin Qin, Xianfeng Liu
Key Laboratory of Geological Hazards in Three Gorges Reservoir Area, Ministry of Education, China Three Gorges University, Yichang, 443002, China
Received 23 August 2009; received in revised form 10 October 2009; accepted 25 October 2009


Abstract: Creep of sliding zone soils may cause significant displacement in large-scale landslides in the Three Gorges reservoir area. To investigate the effects of water on the soil creep behavior of the Qianjiangping landslide, a series of unsaturated triaxial creep tests on the sliding zone soils were performed. Based on the analyses of testing results, a new stress intensity incorporating matric suction was defined and an unsaturated Singh-Mitchell creep model was developed. Predicted results are in good agreement with the experimental results, which indicates that the established unsaturated model can reasonably simulate the effects of water on the soil creep behavior of the landslide. Finally, relationships between matric suction and the parameters of the model were analyzed. This study provides a calculation model and parameters for the evaluation of long-term stability of landslides under the influence of water.
Key words: Qianjiangping landslide; matric suction; creep; Singh-Mitchell creep model

2010-02-08.pdf (514 K) 下载次数:56

Shear strength of an unsaturated weakly expansive soil

Weimin Ye1, 2, Yawei Zhang1, Bao Chen1, Xiuhan Zhou3, Qiang Xie3
1 Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai, 200092, China
2 United Research Center for Urban Environment and Sustainable Development of Ministry of Education, Shanghai, 200092, China
3 Wuhan—Shiyan Expressway Management Bureau in Hubei Province, Wuhan, 430000, China
Received 28 March 2010; received in revised form 14 May 2010; accepted 18 May 2010


Abstract: To study the weakly expansive clay obtained from a slope along Wuhan—Shiyan expressway in Hubei Province, soil-water property tests and some unsaturated triaxial tests with suction control were conducted, and the soil-water retention curve (SWRC) and unsaturated shear strength of this soil were obtained. Results show that the air-entry suction and the residual degree of saturation of the tested soil are 106 kPa and 8%, respectively. The boundary effect zone and the transition zone can be identified on the desorption curve, but the residual zone is not so obvious. The unsaturated shear strength increases as suction increases within the range of controlled suction in the test, and friction angle, b, in the triaxial shear test is 17.6°. Based on the results, constitutive models for predicting the unsaturated shear strength using the SWRC were evaluated, and comparisons between prediction and measurement were made. It is concluded that for engineering purpose, the constitutive model should be carefully selected based on soil properties when predicting the unsaturated shear strength using the SWRC.
Key words: unsaturated soil; soil-water retention curve (SWRC); weakly expansive soil; suction; shear strength

2010-02-09.pdf (456 K) 下载次数:53

Quantification of dynamic tensile parameters of rocks using a modified Kolsky tension bar apparatus

S. Huang1, Rong Chen1, 2, K. W. Xia1*
1 University of Toronto, Toronto, M5S 1A4, Canada
2 National University of Defense Technology, Changsha, 410073, China
Received in 12 May 2010; received in revised form 20 May 2010; accepted 23 May 2010


Abstract: For brittle materials, the tensile strength plays an important role in mechanical analyses and engineering applications. Although quasi-static direct and dynamic indirect tensile strength testing methods have already been developed for rocks, the dynamic direct pull test is still necessary to accurately determine the tensile strength of rocks. In this paper, a Kolsky tension bar system is developed for measuring the dynamic direct tensile strength of rocks. A dumbbell-shaped sample is adopted and attached to the bars using epoxy glue. The pulse shaping technique is utilized to eliminate the inertial effect of samples during test. The single pulse loading technique is developed for the effective microstructure analyses of tested samples. Two absorption devices are successfully utilized to reduce the reflection of waves in the incident bar and transmitted bar, respectively. Laurentian granite (LG) is tested to demonstrate the feasibility of the proposed method. The tensile strength of LG increases with the loading rate. Furthermore, the nominal surface energy of LG is measured, which also increases with the loading rate.
Key words: Kolsky tension bar system; dynamic tensile strength; single pulse loading

2010-02-10.pdf (245 K) 下载次数:47

Microstructural evolution and physico-chemical behavior of compacted clayey soil submitted to an alkaline plume

D. Deneele1, O. Cuisinier2, V. Hallaire3, F. Masrouri2
1 Laboratoire Central des Ponts et Chaussées, Bouguenais, 44341, France
2 Nancy Université, Vandœuvre lès Nancy, 54501, France
3 UMR INRA/Agrocampus, Rennes, 35042, France
Received 21 May 2009; received in revised form 23 November 2009; accepted 15 December 2009


Abstract: In the French concept of deep nuclear waste repositories, the galleries should be backfilled with excavated argillite after the site has been filled. Some additives like lime could be used to improve the mechanical characteristics of the argillite. After thousands of years, the degradation of the concrete lining of the galleries will generate an alkaline solution (pH value > 12) that will diffuse through the backfill. This study presents the effect of a saturated Ca(OH)2 solution circulation through lime-treated sample at 60 °C for 3, 6 and 12 months, respectively. The effect of such circulation on the lime-treated Manois argillite (MA) was assessed by petrographical examination coupled to image analysis and scanning electron microscopy (SEM) equipped with energy dispersive X-ray (EDX) analyser of soil pieces. The objective of this study is to make the link among the mineralogical transformations, the textural and mechanical changes produced in the compacted clayey soil as a consequence of the alkaline solution circulation.
Key words: argillite; lime treatment; petrographical examination; scanning electron microscopy (SEM); image analysis; microstructure

2010-02-11.pdf (1367 K) 下载次数:47

谢谢楼主！！