Main Objectives

The main objectives of DECOVALEX THMC were the study of THMC processes important for PA and SA and the investigation of EDZ. This phase consisted of four BMT's and 1 TC's. A BMT is a Benchmark Test in which the output of different computer codes are compared for a particular problem. A TC is a Test Case in which the output of one or more computer programs are compared against reality.

BMT1: influence of near-field THM couplings on PA (Task A)

• model calibration of rock damage and bentonite models on lab tests and in-situ experiments
• THM analysis of a near field hypothetical repository
• calculation of PA indicators

Discussion:

• overall consistent results between teams
• Possible improvement : extent and properties of EDZ

BMT2: Evolution of the EDZ in crystalline rocks (Task B)

• lab testing and modeling of mechanical strength of granite
• THMC analysis of an emplacement drift in a hypothetical repository

Discussion:

• variety of models used for EDZ simulation
• Possible improvement: scale and time dependant strength properties – use of micromechanics

BMT3: Long term changes in EDZ due to THM and THC processes (Task D)

• THM simulations of a Febex type ( saturated granite with buffer) and of a YM type (unsaturated tuff without buffer) repositories
• THC simulations of a Febex type and of a YM type repositories

Discussion:

• overall good agreement between predictions
• Possible improvements:
  • shear induced permeability changes
  • accounting for reaction kinectics
  • long term MC couplings

BMT4: THMC simulation of the effects of a glaciation (Task E)

• infiltration of glacial meltwaters to the subsurface
• anomalous hydraulic head
• groundwater flow under permafrost conditions

Discussion:

• shortcomings due to 2D analysis compared to 3D
• Possible improvements:
  • fracture reactivation mechanisms
  • coupling with reactive transport model

TC1: Evolution of the EDZ in Tournemire argillite (France)

• modelling the extent of EDZ around a 100 years old tunnel
• modelling the evolutions of EDZ around 3 openings of different ages
• modelling a mine-by-test around a 2003 gallery

Discussion:

• instantaneous failure mechanisms well understood
• Possible improvement: modelling delayed failure mechanims