Modelling the induced slip of a fault in argillaceous rock


DECOVALEX-2019 Task B addresses important issues related to potential creation of permeable flow paths for contaminant transport in otherwise low permeability argillaceous rocks. Such flow paths could be created by reactivating faults of various sizes by thermal, hydraulic and mechanical disturbance during operational or post-closure period. Faults might be reactivated by pore pressure changes induced by thermal pressurization (Rutqvist et al. 2014) or by gas generation. The objective of DECOVALEX-2019, Task B is to develop, compare and validate models for activation of minor and major faults, including mechanical responses and associated changes in fault permeability. Task B uses field data from fault activation experiments recently performed at the Mont Terri underground research laboratory, Switzerland (Gulielmi, 2016). Figure 1 provides an overview of this set of experiments, which in the Mont Terri project is denoted as the FS Experiment. The experiment explores the couplings between fault reactivation in a clay host rock and the potential enhanced fluid displacement through a previously low-permeability formation. international Mont Terri rock laboratory in Switzerland.

Figure 1. Mt Terri fault activation experiment setting (Guglielmi, 2016). A – Mt Terri main fault with the location of the experiment (red squares- seismic sensors, blue squares-piezometers, blue rectangles-injection and monitoring interval). B –Cross section of the Main Fault with the locations of the packed-off sections.

External Collaboration

The work being conducted under Task B has a direct bearing on a wide range of sub-surface geo-engineering applications beyond geological radioactive waste disposal. We are therefore interested in organisations not traditionally part of DECOVALEX or the radioactive waste management industry, to participate in this task. The project feels that there is a real opportunity for mutual benefit by bringing broader Earth science expertise to bear on the data. This is a new and exciting step for the DECOVALEX project; if you have a potential interest in this task, please contact Jens Birkholzer in the first instance, and we would be delighted to initiate a discussion.


The Task B of DECOVALEX-2019 is planned to be conducted in the following three steps with progressively increasing complexity:

  1. Model inception: A benchmark calculation on activation of a single fault plane
  2. Minor fault activation: Interpretative modelling of observed minor fault-activation
  3. Major fault activation: Interpretative modelling of observed activation in a major fault

The idea is to start in Step 1 with modelling of a single fault plane broadly representing the minor fault to be modelled in Step 2. It is a simplified representation of the fault plane and geometry and will be used for the modelling teams to familiarize themselves with the problem and allow for necessary model developments and testing related to modelling of fault activation processes. This could include important aspects of developing and testing new constitutive models for fault hydro-mechanical behavior. The real step pressure injection scheme will be applied during this initial benchmark modelling and reasonable estimated properties for Opalinus Clay and the minor fault will be taken from the site investigations at Mont Terri to facilitate a smooth transition to Step 2. The simulations in Step 1 will be conducted in both 2D and 3D to facilitate comparison of model results for benchmarking of the different codes.


The following lists Research Teams participating in DECOVALEX-2019 Task B and their Funding Organizations:

  • Switzerland: Swiss Federal Nuclear Safety Inspectorate (ENSI) funded by ENSI
  • Taiwan: Institute of Nuclear Energy Research (INER) funded by Taiwan Power Company
  • Canada: Canadian Nuclear Safety Commission (CNSC) funded by CNSC
  • Germany: Federal Institute for Geosciences and Natural Resources (BGR) and Helmholtz Centre for Environmental Research (UFZ), funded by BGR
  • Republic of Korea: Korea Institute of Geoscience and Mineral Resources (KIGAM) funded by Korea Atomic Energy Research Institute (KAERI)
  • USA: Lawrence Berkeley National Laboratory (LBNL) funded by the U.S. Department of Energy (DOE)
Figure 2. HPPP probe protocol; (a) Schematic representation of the HPPP probe – Deformation of the red part of the probe captures the relative displacement of the anchors which is induced by the poro-elastic deformation of the fracture walls. (b) Photograph of the deformation sensor in the central part of the probe. This part is connected to the upper and lower packers before lowering the probe in a borehole. When anchored to the borehole walls, this part is free to move from the remaining HPPP probe elements (Guglielmi et al., 2014).

Further Information

For further information, please contact the task leaders, Dr. Bastian Graupner and Dr. Jonny Rutqvist


  1. Guglielmi Y. In-situ clay faults slip hydro-mechanical characterization (FS experiment), Mont Terri underground rock laboratory. Lawrence Berkeley National Laboratory, Report LBNL-XXXX March (2016).
  2. Guglielmi, Y., Cappa, F., Lanc, H., Janowczyk, J.B., Rutqvist, J., Tsang, C.-F. and Wang, J.S.Y. ISRM suggested method for step-rate injection method for fracture in-situ properties (SIMFIP): Using a 3-component Borehole Deformation Sensor. Rock Mechanics and Rock Engineering 47, 303–311 (2014).
  3. Rutqvist, J., Zheng, L., Chen, F., Liu, H.-H., and Birkholzer, J. Modeling of Coupled Thermo-Hydro-Mechanical Processes with Links to Geochemistry Associated with Bentonite-Backfilled Repository Tunnels in Clay Formations. Rock Mechanics and Rock Engineering, 47, 167–186 (2014).