Developments in a Coupled Thermal- Hydraulic-Chemical-Geomechanical Model for Soil and Concrete

Transcription

1 Developments in a Coupled Thermal- Hydraulic-Chemical-Geomechanical Model for Soil and Concrete S.C. Seetharam * and D. Jacques 24 th October 2013 * suresh.seetharam@sckcen.be (Belgian Nuclear Research Centre) 1

2 Outline Potential applications Objective Governing equations COMSOL-MATLAB Sample Benchmarks Conclusions and perspectives 2

3 Potential applications Significant experimental and numerical research on coupled THCM behaviour for soil and concrete applications. Nuclear waste repository Ground freezing Petroleum Geotechnical in general Current interest Deep disposal Near-Surface disposal 3

4 Potential applications THCM: In situ Processes in deep disposal repository in Boom Clay CHM: Impact of bitumen waste on Boom clay THM Design phase - Half scale test - Supercontainer H, CM, CH: Near surface disposal concept based on concrete as predominant material 4

5 Well known process interaction matrix for Porous media applications Temperature Hydraulic Chemical Mechanical Temperature Conduction (Fourier s Law) Convection Dufour effect Volumetric deformation Hydraulic Thermal osmosis Pressure flow (Darcy s law) Chemical osmosis Volumetric deformation Chemical Soret effect Advection Diffusion (Fick s Law)+Reactions Volumetric deformation Mechanical Thermal expansion Swelling/Shrinkage Swelling/Shrinkage Stress/Strain Equilibrium 5

6 Objective Develop a generic fully coupled THCM model within COMSOL-MATLAB environment THCM Model (COMSOL) Geochemical Model Source term for the "C component" (e.g. PHREEQC) 6

7 Governing equations Energy conservation THERMAL 1 ncpss CplSll T TrLnSgv n C pv S gv C pda S g da t C v C v v C v pl l l pv g v T v v L T T l g v r pda g da Mass conservation pore water pressure l v l g. lklm 0 z t t lvv vvg.. HYDRAULIC PORE WATER PORE GAS Weakly or Strongly coupled Stress equilibrium (GEO)MECHANICAL. C: ε - ε - ε P IPI b 0 th ie f s Mass conservation pore gas pressure. dav g ggda g g da da t CHEMICAL Mass conservation 7 Charge conservation lci ELECTROCHEMICAL t l e DzFc i i i Dici e F RT l cz i i 0. Diciln i R i Dc i iln ici T c iv l T

8 Implementation 3 governing equations (TH) P f P g T H Multicomponent (as many governing equations as the number of chemicals, C i ) C PDE form (based on equations in slide 7) M Inbuilt solute interface (introduce cross coupling terms using source term) Dilute species model used because it offers numerical stability schemes this means the formulation requires further adaptation to include porosity Geomechanical (M) Inbuilt solid mechanics interface (introduce cross coupling terms (e.g. pore water pressure) and geomechanical constitutive laws applicable for soil and concrete) Implemented soil models (useful for describing Boom clay behaviour) using COMSOL's generic plasticity feature: Mohr-Coulomb Drucker-Prager Etc 8

9 Benchmark 1 Infiltration under isothermal conditions (Hydromechanical coupling) l l. lklm z t. C:ε P IPI b0 f s 9

10 Infiltration under isothermal conditions Relaive humidity (%) z = 10 cm (COMSOL) 50 z = 20 cm (COMSOL) 40 z = 30 cm (COMSOL) 30 z = 30 cm (measured) 20 z = 20 cm (measured) z = 10 cm (measured) Time (Hours) Degree of saturation Nonlinear elasticity Linear elasticity Test equipment (CIEMAT, Spain) and model idealisation for the infiltration experiment under isothermal conditions Porosity: COMSOL (left) and Chen et al. (right) scale not same 10

11 Benchmark 2 THM response of the in-situ ATLAS III Experiment nc T T r pl ll T 1 ps s nc S t T C T T plv l l r l T l. lklt m t. C: ε - ε - ε I 0 th ie P s 11

12 Pore pressure fixed = 4.5 MPa Conceptual model and data Key features: Fully coupled THM Boom clay Axisymmetric Fully saturated Viscosity and density as a function of temperature Thermo-Elasto-plastic (Drucker Prager) model 2 3sin f J pcctg 3 sin 2 3sin g J pcctg 3 sin Two materials = steel + boom clay COMSOL computation time = 0.5 hours Chen and Li,

13 Temperature and pore water pressure evolution 13

14 Radial displacement, mean effective stress and plastic strain Note: Plastic region is insignificant and hence not shown (limited to few elements in the domain. 14

15 Benchmark 3 Chemo-osmotic flow l l. lklm 0 t c l t i.d c cv i i i l 15

16 Keijzer s experiment Clay zone Pore water pressure (Pa) COMSOL Measured (Bader and Kooi, 2005) E E E E E+06 Time (seconds) Pressure evolution at the interface between the left porous stone and the clay Transient pressure profile 16

17 Benchmark 3 Reactive transport (COMSOL-MATLAB) c l t i. D c c R i i iv l i Phreeqc coupling via MATLAB use sequential noniterative approach (other approaches also tried, no difference for the specific problems chosen) 17

18 Ion exchange, Mineral dissolution verifications Inlet Outlet CaCl 2 Na-K-NO3 2- +Exchanger Advection-diffusion Comparison made with open source code HP1, developed at SCK-CEN 5 Low ph boundary Ca 20 mm, ph 12.5 Diffusion only Initial portlandite =4 mm Portlandite (mm) COMSOL PHREEQC Time (hrs.) Input data: Patel, R.A., Perko, J., Jacques, D., De Schutter, G., Breugel, K. V., Ye, G., A versatile pore-scale multicomponent reactive transport approach based on Lattice Boltzmann Method: Application to cementitious systems. Jour. Phy. and Chem. of the Earth (submitted) Portlandite dissolution Note: More complex chemistry successfully demonstrated 18 in a forthcoming journal publication

19 Conclusions and perspectives Model implementation and benchmark results highly encouraging. Further work ongoing in terms of chemo-mechanical coupling, plus more and more verifications/validations. Computational constraints especially iterating between COMSOL- MATLAB. Perhaps COMSOL can consider this in future versions. COMSOL: easy to implement and serves as a powerful research tool. 19

20 - PLEASE NOTE! This presentation contains data, information and formats for dedicated use ONLY and may not be copied, distributed or cited without the explicit permission of the. If this has been obtained, please reference it as a personal communication. By courtesy of. Studiecentrum voor Kernenergie Centre d'etude de l'energie Nucléaire Belgian Nuclear Research Centre Stichting van Openbaar Nut Fondation d'utilité Publique Foundation of Public Utility Registered Office: Avenue Herrmann-Debrouxlaan 40 BE-1160 BRUSSELS Operational Office: Boeretang 200 BE-2400 MOL 20