Geomechanical and hydrogeological characterization of fracture systems in Banyoles Karst caprock units, Catalunya / Aline Concha Dimas, Ivan Fabregat
Concha Dimas, AlineEn:
15th ISRM Congress ; 9-14 October 2023. Salzburg : Austrian Society for Geomechanics, 2023. p. 83-89
Banyoles karst systems, located in NE Catalonia, is tectonically controlled, and associated to an artesian aquifer. This karst system is formed at the surface by a cap layer of competitive marls and calcareous rocks above a highly dissolving thick unit of gypsum with depth larger than 20 m. The voids left by upward water flow of the artesian aquifer generates sinkholes at the surface. First, we analyzed aerial photographs to describe the latest karst activity from 1945 up to the present. Secondly, we performed eighteen scanline surveys to describe the cap-rock structure (Jv and RQD) and describe hydraulic aperture and transmissivity (ac, Tf) of each joint set. In the cap rock units, we found up to 7 fracture systems that define medium-large block size. Two fractures have the highest Tf values, order of magnitude between 10-1 and 10-3, critical for the generation of collapses where the gypsum unit is shallow.
