Tesis doctoral de Juan Jorge Muñoz
This thesis deals with the theoretical and experimental analysis of the coupled thermo-hydro-mechanical (thm) processes developed in geological formations suitable for the repository of radioactive waste of high activity. In the last decades, the argillaceous formations have been studied to be used as geological barriers, due to its reduced hydraulic conductivity. The degradation of clay shales induced by temperature and saturation effects is an important factor which is currently being investigated in large scale in situ tests as well as in laboratory studies. in this thesis, the opalinus clay rock has been widely characterized by means of laboratory tests. From a macro-structural point of view, the water retention curve, hydraulic conductivity, strength and deformability parameters have been determined. The micro-structural analysis is focused to the mineralogical characterization obtained by means of x ray diffraction, pore size distribution (psd) determined by means of mercury intrusion porosimetry (mip) and scanning electronic microscopy (sem). the thesis describes also a large scale heating in situ test designed to analyze the interaction between the engineer barrier (compacted bentonite blocks) and by the geological barrier, (opalinus clay). This interaction has been analyzed by means of numerical simulations performed with the finite element code code_bright. A thermo hydraulic cell was specially designed to observe the coupled thm behaviour of the clay shale rock under drained and undrained conditions by means of heat pulses. Thermal and hydraulic parameters of rock were determined by means of back-analysis performed with the help of code_bright. in order to reproduce the anisotropic and brittle behaviour of the clay shale, a 3d mechanical constitutive model has been formulated and implemented in code_bright. The constitutive model is formulated in a viscoplastic framework and it considers the strength and deformability of both matrix and discontinuities (joints). The failure criterion of the matrix and the joints is defined by means of hyperbolic yield surfaces in the p-j and ¿-¿ stress space, respectively. The brittle behaviour of clay shale is simulated by means of isotropic and kinematic softening defined in terms of a work-hardening criterion. The anisotropic constitutive model has been calibrated against triaxial laboratory tests performed on specimens with a main family of discontinuities having different dip angles. The constitutive model has been applied to a 3d numerical simulation of an in-situ heating test. A 3d numerical simulation of a ventilation test performed in an unlined micro tunnel was also performed in order to reproduce the changes of the rock permeability by drying effects. In this case, a hydraulic model able to consider the changes in joint thickness by drying effects has been developed to reproduce the changes of permeability in underground excavations.
Datos académicos de la tesis doctoral «Thermo-hydro-mechanical analysis of soft rock. application to a large scale heating test and large scale ventilation test.«
- Título de la tesis: Thermo-hydro-mechanical analysis of soft rock. application to a large scale heating test and large scale ventilation test.
- Autor: Juan Jorge Muñoz
- Universidad: Politécnica de catalunya
- Fecha de lectura de la tesis: 30/03/2007
Dirección y tribunal
- Director de la tesis
- Eduardo Alonso Pérez De ágreda
- Tribunal
- Presidente del tribunal: alberto Ledesma villalba
- césar Sagaseta millán (vocal)
- Fernando Pardo de santayana carrillo (vocal)
- pierre Delage (vocal)