The objective is to characterise the hydro-mechanical behaviour of rocks with the help of laboratory tests and to apply these findings to the study of underground sites and reservoirs.

The principle consists of applying various types of mechanical, thermal, hydrological and chemical stresses to a rock sample in order to reproduce conditions underground. We then develop behavioural models and perform numerical simulations based on the experimental data acquired.

For example, we can study the mechanisms of failure of a cylindrical rock sample by compression under a mechanical press. During the compression test, we record the sample deformations and the induced microseismicity. The data collected then allow us to determine the fracturing conditions of the material.

The strengths of this experimental platform reside in the coupling between experimental and numerical modelling to best reproduce the complexity of the subterranean environment.

The ‘Multi-Scale Hydrogeomechanics’ team maintains two experimental facilities.

The ‘Rock Mechanics’ laboratory is equipped with:

• mechanical presses;
• pressure generators;
• high-capacity triaxial compression cells for conducting deformation and acoustic measurements for studying the mechanical and physical behaviour of rocks under mechanical strain, temperature and high-pressure fluid circulation;
• nano- and micro-indentors for investigating micro-mechanical behaviour;
• a range of geotechnical (hardness-abrasion tests, Los Angeles, climatic chambers etc…) and petrophysical apparatus (mercury porosimeter, sorption analyser…);
• a rock machining workshop.

In addition, the ‘Transfer in Porous Media’ laboratory hosts:

• 2D artificial porous media (etched micromodels, Hele-Shaw cells, sinusoidal fractures) and performance optical equipment (a high-resolution CCD camera, microscopes, particle imaging velocimetry and laser-induced fluorescence) for the study of flow and transfer processes at pore-scale and Darcy-scale;
• instrumented soil columns (tensiometers, porous candles etc…) for 1D-flow studies;

an experimental room dedicated to the study of biological processes in porous media (e.g., biodegradation, bacterial growth).

These experimental means are coupled to high-performance modelling resources (e.g., cluster computation, GPU stations) for 3D simulation of coupled processes: 

Software packages for modelling thermo-hydro-mechanical phenomena in continuous and discontinuous environments (Code_Aster), multiphase multicomponents (Comsol Multiphysics) and hydrogeological modelling (Groundwater Modeling System)

Nanoindentation experimental system

Microindentation testing (2D punch modelling)

Subcritical fracture propagation testing (double torsion)

Triaxial microcompression cell (+/- 1.5 mm displacement sensor and 500N force sensor)

Cylindrical sample placed in  a triaxial macro-compression cell

Measurement of radial and axial displacement (extensometer)

Use of optical imaging and microscopy to monitor transport of solutes in biofilms (experimental room dedicated to study of biological processes)

Laser-induced fluorescence system

Imbibition experiments in a micromodel

2D fracture model