Impact of weathering on macro-mechanical properties of chalks

Christophe Auvray (1) , Noémie Lafrance (2, 1) , Mountaka Souley (2) , Vincent Labiouse

1 GeoRessources
2 INERIS - Institut National de l'Environnement Industriel et des Risques

Chalk has long been used as a strong building material. The shallow underground room-andpillar quarries where the chalk was extracted now lie abandoned and endure the effects of time and weathering, increasing their risk of collapse. The risk of instability is an issue for more than 10 000 towns in France. We have studied the physico-mechanical behaviour and ageing of two types of chalk in underground quarries in the Parisian Basin, France. The dolomitic chalk (Saint-Martin-Le-Noeud) exhibits variations in mechanical and physical properties with horizontal pillar depth, and both density and compressive strength appear to increase outwards from the core to the wall of the pillar. SEM analysis reveals progressive degradation and increasing homogeneity of the grains from the edge to the inside of the pillar. In contrast, in physico-mechanical tests and SEM analyses performed on the Estreux glauconitic chalk, no significant variation was observed between the pillar wall and pillar core.

Domains: Sciences of the Universe [physics]; Earth Sciences

Christophe Auvray, Noémie Lafrance, Mountaka Souley, Vincent Labiouse. Impact of weathering on macro-mechanical properties of chalks. International Symposium of ISRM "Rock Mechanics and Rock Engineering : From the Past to the Future" (EUROCK 2016), Aug 2016, Cappadocia, Turkey. pp.885-890. ⟨ineris-01854305⟩