ABSTRACT
The Saint-Jean Monolithic Church of Aubeterre-sur-Dronne (France) is an underground medieval Church, dug directly in limestone strata, at the foot of a cliff.
Following a general deterioration of the stability conditions, a consortium led by Agence GOUTAL, Chief Architect of Heritage Monuments, has been mandated with co-contractors for detailed diagnosis of this underground Church. Antea Group has the responsibility of the geotechnical and hydrogeological diagnosis. The mission program includes a diagnosis and survey of the rock cracks, an hydrogeological expertise with water table monitoring, a geotechnical survey including borehole core sampling and crack monitoring.
This survey shows that the rock is relatively homogeneous in terms of lithology and hydraulic conductivity but has an important spatial variability for the mechanical properties. The limestone massif is very porous and fed mainly by infiltration from the upper ground level. Even if the Church is affected by a dense crack network, the monitoring showed that only one sector presents crack opening evolution and needs a specific study for its reinforcement.
