Hydro-mechanical numerical modelling of the opening and closing of desiccation cracks in clayey rock

Abstract

The monitoring during one year of a gallery front of the Tournemire experimental station by optical metrology showed the presence of desiccation cracks sensitive to relative humidity variations in the gallery. The cracks are closed in summer, when RH is included between 90% and 98%, and open in winter when RH is lower. These cracks exhibit maximal aperture values ranging from 0.2 to 0.5 mm and different opening kinematics. One possible reason for these differences in surface opening could be the different crack length penetration within the rock mass, which the optical experimental method does not allow to measure. In order to highlight a possible relationship between the opening and the penetration of the desiccation cracks, we use a coupled hydro-mechanical numerical modelling taking explicitly into account the desaturation and resaturation of claystone. We focus on the aperture of three sub-horizontal cracks. The first results obtained remain quite qualitative, but the estimates of cracks penetration inferred by comparison between in situ measurements and numerical results are consistent with the results provided by geophysics.

Keywords:

• Desiccation cracks
• hydro-mechanical couplings
• digital image correlation
• numerical modelling

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research has received financial support from the French National Research Agency (ANR) through the HydroGeoDam project under Grant No. ANR-17-CE06-0016.